moved 'corec' from ssh://hg@bitbucket.org/jasmin_blanchette/nonprim-corec to Isabelle
authorblanchet
Tue, 22 Mar 2016 12:39:37 +0100
changeset 62692 0701f25fac39
parent 62691 9bfcbab7cd99
child 62693 0ae225877b68
moved 'corec' from ssh://hg@bitbucket.org/jasmin_blanchette/nonprim-corec to Isabelle
src/HOL/Library/BNF_Corec.thy
src/HOL/Library/Library.thy
src/HOL/Tools/BNF/bnf_gfp_grec.ML
src/HOL/Tools/BNF/bnf_gfp_grec_sugar.ML
src/HOL/Tools/BNF/bnf_gfp_grec_sugar_tactics.ML
src/HOL/Tools/BNF/bnf_gfp_grec_sugar_util.ML
src/HOL/Tools/BNF/bnf_gfp_grec_tactics.ML
src/HOL/Tools/BNF/bnf_gfp_grec_unique_sugar.ML
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Library/BNF_Corec.thy	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,213 @@
+(*  Title:      HOL/Library/BNF_Corec.thy
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Author:     Aymeric Bouzy, Ecole polytechnique
+    Author:     Dmitriy Traytel, ETH Zurich
+    Copyright   2015, 2016
+
+Generalized corecursor sugar ("corec" and friends).
+*)
+
+chapter {* Generalized Corecursor Sugar (corec and friends) *}
+
+theory BNF_Corec
+imports Main
+keywords
+  "corec" :: thy_decl and
+  "corecursive" :: thy_goal and
+  "friend_of_corec" :: thy_goal and
+  "coinduction_upto" :: thy_decl
+begin
+
+lemma obj_distinct_prems: "P \<longrightarrow> P \<longrightarrow> Q \<Longrightarrow> P \<Longrightarrow> Q"
+  by auto
+
+lemma inject_refine: "g (f x) = x \<Longrightarrow> g (f y) = y \<Longrightarrow> f x = f y \<longleftrightarrow> x = y"
+  by (metis (no_types))
+
+lemma convol_apply: "BNF_Def.convol f g x = (f x, g x)"
+  unfolding convol_def ..
+
+lemma Grp_UNIV_id: "BNF_Def.Grp UNIV id = (op =)"
+  unfolding BNF_Def.Grp_def by auto
+
+lemma sum_comp_cases:
+  assumes "f o Inl = g o Inl" and "f o Inr = g o Inr"
+  shows "f = g"
+proof (rule ext)
+  fix a show "f a = g a"
+    using assms unfolding comp_def fun_eq_iff by (cases a) auto
+qed
+
+lemma case_sum_Inl_Inr_L: "case_sum (f o Inl) (f o Inr) = f"
+  by (metis case_sum_expand_Inr')
+
+lemma eq_o_InrI: "\<lbrakk>g o Inl = h; case_sum h f = g\<rbrakk> \<Longrightarrow> f = g o Inr"
+  by (auto simp: fun_eq_iff split: sum.splits)
+
+lemma id_bnf_o: "BNF_Composition.id_bnf \<circ> f = f"
+  unfolding BNF_Composition.id_bnf_def by (rule o_def)
+
+lemma o_id_bnf: "f \<circ> BNF_Composition.id_bnf = f"
+  unfolding BNF_Composition.id_bnf_def by (rule o_def)
+
+lemma if_True_False:
+  "(if P then True else Q) \<longleftrightarrow> P \<or> Q"
+  "(if P then False else Q) \<longleftrightarrow> \<not> P \<and> Q"
+  "(if P then Q else True) \<longleftrightarrow> \<not> P \<or> Q"
+  "(if P then Q else False) \<longleftrightarrow> P \<and> Q"
+  by auto
+
+lemma if_distrib_fun: "(if c then f else g) x = (if c then f x else g x)"
+  by simp
+
+
+section \<open>Coinduction\<close>
+
+lemma eq_comp_compI: "a o b = f o x \<Longrightarrow> x o c = id \<Longrightarrow> f = a o (b o c)"
+  unfolding fun_eq_iff by simp
+
+lemma self_bounded_weaken_left: "(a :: 'a :: semilattice_inf) \<le> inf a b \<Longrightarrow> a \<le> b"
+  by (erule le_infE)
+
+lemma self_bounded_weaken_right: "(a :: 'a :: semilattice_inf) \<le> inf b a \<Longrightarrow> a \<le> b"
+  by (erule le_infE)
+
+lemma symp_iff: "symp R \<longleftrightarrow> R = R^--1"
+  by (metis antisym conversep.cases conversep_le_swap predicate2I symp_def)
+
+lemma equivp_inf: "\<lbrakk>equivp R; equivp S\<rbrakk> \<Longrightarrow> equivp (inf R S)"
+  unfolding equivp_def inf_fun_def inf_bool_def by metis
+
+lemma vimage2p_rel_prod:
+  "(\<lambda>x y. rel_prod R S (BNF_Def.convol f1 g1 x) (BNF_Def.convol f2 g2 y)) =
+   (inf (BNF_Def.vimage2p f1 f2 R) (BNF_Def.vimage2p g1 g2 S))"
+  unfolding vimage2p_def rel_prod.simps convol_def by auto
+
+lemma predicate2I_obj: "(\<forall>x y. P x y \<longrightarrow> Q x y) \<Longrightarrow> P \<le> Q"
+  by auto
+
+lemma predicate2D_obj: "P \<le> Q \<Longrightarrow> P x y \<longrightarrow> Q x y"
+  by auto
+
+locale cong =
+  fixes rel :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> ('b \<Rightarrow> 'b \<Rightarrow> bool)"
+    and eval :: "'b \<Rightarrow> 'a"
+    and retr :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> 'a \<Rightarrow> bool)"
+  assumes rel_mono: "\<And>R S. R \<le> S \<Longrightarrow> rel R \<le> rel S"
+    and equivp_retr: "\<And>R. equivp R \<Longrightarrow> equivp (retr R)"
+    and retr_eval: "\<And>R x y. \<lbrakk>(rel_fun (rel R) R) eval eval; rel (inf R (retr R)) x y\<rbrakk> \<Longrightarrow>
+      retr R (eval x) (eval y)"
+begin
+
+definition cong :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> bool" where
+  "cong R \<equiv> equivp R \<and> (rel_fun (rel R) R) eval eval"
+
+lemma cong_retr: "cong R \<Longrightarrow> cong (inf R (retr R))"
+  unfolding cong_def
+  by (auto simp: rel_fun_def dest: predicate2D[OF rel_mono, rotated]
+    intro: equivp_inf equivp_retr retr_eval)
+
+lemma cong_equivp: "cong R \<Longrightarrow> equivp R"
+  unfolding cong_def by simp
+
+definition gen_cong :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> 'a \<Rightarrow> 'a \<Rightarrow> bool" where
+  "gen_cong R j1 j2 \<equiv> \<forall>R'. R \<le> R' \<and> cong R' \<longrightarrow> R' j1 j2"
+
+lemma gen_cong_reflp[intro, simp]: "x = y \<Longrightarrow> gen_cong R x y"
+  unfolding gen_cong_def by (auto dest: cong_equivp equivp_reflp)
+
+lemma gen_cong_symp[intro]: "gen_cong R x y \<Longrightarrow> gen_cong R y x"
+  unfolding gen_cong_def by (auto dest: cong_equivp equivp_symp)
+
+lemma gen_cong_transp[intro]: "gen_cong R x y \<Longrightarrow> gen_cong R y z \<Longrightarrow> gen_cong R x z"
+  unfolding gen_cong_def by (auto dest: cong_equivp equivp_transp)
+
+lemma equivp_gen_cong: "equivp (gen_cong R)"
+  by (intro equivpI reflpI sympI transpI) auto
+
+lemma leq_gen_cong: "R \<le> gen_cong R"
+  unfolding gen_cong_def[abs_def] by auto
+
+lemmas imp_gen_cong[intro] = predicate2D[OF leq_gen_cong]
+
+lemma gen_cong_minimal: "\<lbrakk>R \<le> R'; cong R'\<rbrakk> \<Longrightarrow> gen_cong R \<le> R'"
+  unfolding gen_cong_def[abs_def] by (rule predicate2I) metis
+
+lemma congdd_base_gen_congdd_base_aux:
+  "rel (gen_cong R) x y \<Longrightarrow> R \<le> R' \<Longrightarrow> cong R' \<Longrightarrow> R' (eval x) (eval y)"
+   by (force simp: rel_fun_def gen_cong_def cong_def dest: spec[of _ R'] predicate2D[OF rel_mono, rotated -1, of _ _ _ R'])
+
+lemma cong_gen_cong: "cong (gen_cong R)"
+proof -
+  { fix R' x y
+    have "rel (gen_cong R) x y \<Longrightarrow> R \<le> R' \<Longrightarrow> cong R' \<Longrightarrow> R' (eval x) (eval y)"
+      by (force simp: rel_fun_def gen_cong_def cong_def dest: spec[of _ R']
+        predicate2D[OF rel_mono, rotated -1, of _ _ _ R'])
+  }
+  then show "cong (gen_cong R)" by (auto simp: equivp_gen_cong rel_fun_def gen_cong_def cong_def)
+qed
+
+lemma gen_cong_eval_rel_fun:
+  "(rel_fun (rel (gen_cong R)) (gen_cong R)) eval eval"
+  using cong_gen_cong[of R] unfolding cong_def by simp
+
+lemma gen_cong_eval:
+  "rel (gen_cong R) x y \<Longrightarrow> gen_cong R (eval x) (eval y)"
+  by (erule rel_funD[OF gen_cong_eval_rel_fun])
+
+lemma gen_cong_idem: "gen_cong (gen_cong R) = gen_cong R"
+  by (simp add: antisym cong_gen_cong gen_cong_minimal leq_gen_cong)
+
+lemma gen_cong_rho:
+  "\<rho> = eval o f \<Longrightarrow> rel (gen_cong R) (f x) (f y) \<Longrightarrow> gen_cong R (\<rho> x) (\<rho> y)"
+  by (simp add: gen_cong_eval)
+lemma coinduction:
+  assumes coind: "\<forall>R. R \<le> retr R \<longrightarrow> R \<le> op ="
+  assumes cih: "R \<le> retr (gen_cong R)"
+  shows "R \<le> op ="
+  apply (rule order_trans[OF leq_gen_cong mp[OF spec[OF coind]]])
+  apply (rule self_bounded_weaken_left[OF gen_cong_minimal])
+   apply (rule inf_greatest[OF leq_gen_cong cih])
+  apply (rule cong_retr[OF cong_gen_cong])
+  done
+
+end
+
+lemma rel_sum_case_sum:
+  "rel_fun (rel_sum R S) T (case_sum f1 g1) (case_sum f2 g2) = (rel_fun R T f1 f2 \<and> rel_fun S T g1 g2)"
+  by (auto simp: rel_fun_def rel_sum.simps split: sum.splits)
+
+context
+  fixes rel eval rel' eval' retr emb
+  assumes base: "cong rel eval retr"
+  and step: "cong rel' eval' retr"
+  and emb: "eval' o emb = eval"
+  and emb_transfer: "rel_fun (rel R) (rel' R) emb emb"
+begin
+
+interpretation base: cong rel eval retr by (rule base)
+interpretation step: cong rel' eval' retr by (rule step)
+
+lemma gen_cong_emb: "base.gen_cong R \<le> step.gen_cong R"
+proof (rule base.gen_cong_minimal[OF step.leq_gen_cong])
+  note step.gen_cong_eval_rel_fun[transfer_rule] emb_transfer[transfer_rule]
+  have "(rel_fun (rel (step.gen_cong R)) (step.gen_cong R)) eval eval"
+    unfolding emb[symmetric] by transfer_prover
+  then show "base.cong (step.gen_cong R)"
+    by (auto simp: base.cong_def step.equivp_gen_cong)
+qed
+
+end
+
+ML_file "../Tools/BNF/bnf_gfp_grec_tactics.ML"
+ML_file "../Tools/BNF/bnf_gfp_grec.ML"
+ML_file "../Tools/BNF/bnf_gfp_grec_sugar_util.ML"
+ML_file "../Tools/BNF/bnf_gfp_grec_sugar_tactics.ML"
+ML_file "../Tools/BNF/bnf_gfp_grec_sugar.ML"
+ML_file "../Tools/BNF/bnf_gfp_grec_unique_sugar.ML"
+
+method_setup corec_unique = \<open>
+  Scan.succeed (SIMPLE_METHOD' o BNF_GFP_Grec_Unique_Sugar.corec_unique_tac)
+\<close> "prove uniqueness of corecursive equation"
+
+end
--- a/src/HOL/Library/Library.thy	Tue Mar 22 12:39:37 2016 +0100
+++ b/src/HOL/Library/Library.thy	Tue Mar 22 12:39:37 2016 +0100
@@ -5,6 +5,7 @@
   BigO
   Bit
   BNF_Axiomatization
+  BNF_Corec
   Boolean_Algebra
   Bourbaki_Witt_Fixpoint
   Char_ord
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,3234 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec.ML
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Author:     Aymeric Bouzy, Ecole polytechnique
+    Author:     Dmitriy Traytel, ETH Zürich
+    Copyright   2015, 2016
+
+Generalized corecursor construction.
+*)
+
+signature BNF_GFP_GREC =
+sig
+  val Tsubst: typ -> typ -> typ -> typ
+  val substT: typ -> typ -> term -> term
+  val freeze_types: Proof.context -> (indexname * sort) list -> typ list -> typ list
+  val dummify_atomic_types: term -> term
+  val enforce_type: Proof.context -> (typ -> typ) -> typ -> term -> term
+  val define_const: bool -> binding -> int -> string -> term -> local_theory ->
+    (term * thm) * local_theory
+
+  type buffer =
+    {Oper: term,
+     VLeaf: term,
+     CLeaf: term,
+     ctr_wrapper: term,
+     friends: (typ * term) Symtab.table}
+
+  val map_buffer: (term -> term) -> buffer -> buffer
+  val specialize_buffer_types: buffer -> buffer
+
+  type dtor_coinduct_info =
+    {dtor_coinduct: thm,
+     cong_def: thm,
+     cong_locale: thm,
+     cong_base: thm,
+     cong_refl: thm,
+     cong_sym: thm,
+     cong_trans: thm,
+     cong_alg_intros: thm list}
+
+  type corec_info =
+    {fp_b: binding,
+     version: int,
+     fpT: typ,
+     Y: typ,
+     Z: typ,
+     friend_names: string list,
+     sig_fp_sugars: BNF_FP_Def_Sugar.fp_sugar list,
+     ssig_fp_sugar: BNF_FP_Def_Sugar.fp_sugar,
+     Lam: term,
+     proto_sctr: term,
+     flat: term,
+     eval_core: term,
+     eval: term,
+     algLam: term,
+     corecUU: term,
+     dtor_transfer: thm,
+     Lam_transfer: thm,
+     Lam_pointful_natural: thm,
+     proto_sctr_transfer: thm,
+     flat_simps: thm list,
+     eval_core_simps: thm list,
+     eval_thm: thm,
+     eval_simps: thm list,
+     all_algLam_algs: thm list,
+     algLam_thm: thm,
+     dtor_algLam: thm,
+     corecUU_thm: thm,
+     corecUU_unique: thm,
+     corecUU_transfer: thm,
+     buffer: buffer,
+     all_dead_k_bnfs: BNF_Def.bnf list,
+     Retr: term,
+     equivp_Retr: thm,
+     Retr_coinduct: thm,
+     dtor_coinduct_info: dtor_coinduct_info}
+
+  type friend_info =
+    {algrho: term,
+     dtor_algrho: thm,
+     algLam_algrho: thm}
+
+  val not_codatatype: Proof.context -> typ -> 'a
+  val mk_fp_binding: binding -> string -> binding
+  val bnf_kill_all_but: int -> BNF_Def.bnf -> local_theory -> BNF_Def.bnf * local_theory
+
+  val print_corec_infos: Proof.context -> unit
+  val has_no_corec_info: Proof.context -> string -> bool
+  val corec_info_of: typ -> local_theory -> corec_info * local_theory
+  val maybe_corec_info_of: Proof.context -> typ -> corec_info option
+  val corec_infos_of: Proof.context -> string -> corec_info list
+  val corec_infos_of_generic: Context.generic -> Symtab.key -> corec_info list
+  val prepare_friend_corec: string -> typ -> local_theory ->
+    (corec_info * binding * int * typ * typ * typ * typ * typ * BNF_Def.bnf * BNF_Def.bnf
+     * BNF_FP_Def_Sugar.fp_sugar * BNF_FP_Def_Sugar.fp_sugar * buffer) * local_theory
+  val register_friend_corec: string -> binding -> int -> typ -> typ -> typ -> BNF_Def.bnf ->
+    BNF_FP_Def_Sugar.fp_sugar -> BNF_FP_Def_Sugar.fp_sugar -> term -> term -> thm -> corec_info ->
+    local_theory -> friend_info * local_theory
+end;
+
+structure BNF_GFP_Grec : BNF_GFP_GREC =
+struct
+
+open Ctr_Sugar
+open BNF_Util
+open BNF_Def
+open BNF_Comp
+open BNF_FP_Util
+open BNF_LFP
+open BNF_FP_Def_Sugar
+open BNF_LFP_Rec_Sugar
+open BNF_GFP_Grec_Tactics
+
+val algLamN = "algLam";
+val algLam_algLamN = "algLam_algLam";
+val algLam_algrhoN = "algLam_algrho";
+val algrhoN = "algrho";
+val CLeafN = "CLeaf";
+val congN = "congclp";
+val cong_alg_introsN = "cong_alg_intros";
+val cong_localeN = "cong_locale";
+val corecUUN = "corecUU";
+val corecUU_transferN = "corecUU_transfer";
+val corecUU_uniqueN = "corecUU_unique";
+val cutSsigN = "cutSsig";
+val dtor_algLamN = "dtor_algLam";
+val dtor_algrhoN = "dtor_algrho";
+val dtor_coinductN = "dtor_coinduct";
+val dtor_transferN = "dtor_transfer";
+val embLN = "embL";
+val embLLN = "embLL";
+val embLRN = "embLR";
+val embL_pointful_naturalN = "embL_pointful_natural";
+val embL_transferN = "embL_transfer";
+val equivp_RetrN = "equivp_Retr";
+val evalN = "eval";
+val eval_coreN = "eval_core";
+val eval_core_pointful_naturalN = "eval_core_pointful_natural";
+val eval_core_transferN = "eval_core_transfer";
+val eval_flatN = "eval_flat";
+val eval_simpsN = "eval_simps";
+val flatN = "flat";
+val flat_pointful_naturalN = "flat_pointful_natural";
+val flat_transferN = "flat_transfer";
+val k_as_ssig_naturalN = "k_as_ssig_natural";
+val k_as_ssig_transferN = "k_as_ssig_transfer";
+val LamN = "Lam";
+val Lam_transferN = "Lam_transfer";
+val Lam_pointful_naturalN = "Lam_pointful_natural";
+val OperN = "Oper";
+val proto_sctrN = "proto_sctr";
+val proto_sctr_pointful_naturalN = "proto_sctr_pointful_natural";
+val proto_sctr_transferN = "proto_sctr_transfer";
+val rho_transferN = "rho_transfer";
+val Retr_coinductN = "Retr_coinduct";
+val sctrN = "sctr";
+val sctr_transferN = "sctr_transfer";
+val sctr_pointful_naturalN = "sctr_pointful_natural";
+val sigN = "sig";
+val SigN = "Sig";
+val Sig_pointful_naturalN = "Sig_pointful_natural";
+val corecUN = "corecU";
+val corecU_ctorN = "corecU_ctor";
+val corecU_uniqueN = "corecU_unique";
+val unsigN = "unsig";
+val VLeafN = "VLeaf";
+
+val s_prefix = "s"; (* transforms "sig" into "ssig" *)
+
+fun not_codatatype ctxt T =
+  error ("Not a codatatype: " ^ Syntax.string_of_typ ctxt T);
+fun mutual_codatatype () =
+  error ("Mutually corecursive codatatypes are not supported (try " ^
+    quote (#1 @{command_keyword primcorec}) ^ " instead of " ^
+    quote (#1 @{command_keyword corec}) ^ ")");
+fun noncorecursive_codatatype () =
+  error ("Noncorecursive codatatypes are not supported (try " ^
+    quote (#1 @{command_keyword definition}) ^ " instead of " ^
+    quote (#1 @{command_keyword corec}) ^ ")");
+fun singleton_codatatype ctxt =
+  error ("Singleton corecursive codatatypes are not supported (use " ^
+    quote (Syntax.string_of_typ ctxt @{typ unit}) ^ " instead)");
+
+fun merge_lists eq old1 old2 = (old1 |> subtract eq old2) @ old2;
+
+fun add_type_namesT (Type (s, Ts)) = insert (op =) s #> fold add_type_namesT Ts
+  | add_type_namesT _ = I;
+
+fun Tsubst Y T = Term.typ_subst_atomic [(Y, T)];
+fun substT Y T = Term.subst_atomic_types [(Y, T)];
+
+fun freeze_types ctxt except_tvars Ts =
+  let
+    val As = fold Term.add_tvarsT Ts [] |> subtract (op =) except_tvars;
+    val (Bs, _) = ctxt |> mk_TFrees' (map snd As);
+  in
+    map (Term.typ_subst_TVars (map fst As ~~ Bs)) Ts
+  end;
+
+fun typ_unify_disjointly thy (T, T') =
+  if T = T' then
+    T
+  else
+    let
+      val tvars = Term.add_tvar_namesT T [];
+      val tvars' = Term.add_tvar_namesT T' [];
+      val maxidx' = maxidx_of_typ T';
+      val T = T |> exists (member (op =) tvars') tvars ? Logic.incr_tvar (maxidx' + 1);
+      val maxidx = Integer.max (maxidx_of_typ T) maxidx';
+      val (tyenv, _) = Sign.typ_unify thy (T, T') (Vartab.empty, maxidx);
+    in
+      Envir.subst_type tyenv T
+    end;
+
+val dummify_atomic_types = Term.map_types (Term.map_atyps (K Term.dummyT));
+
+fun enforce_type ctxt get_T T t =
+  Term.subst_TVars (tvar_subst (Proof_Context.theory_of ctxt) [get_T (fastype_of t)] [T]) t;
+
+fun mk_internal internal ctxt f =
+  if internal andalso not (Config.get ctxt bnf_internals) then f else I
+fun mk_fp_binding fp_b pre = Binding.map_name (K pre) fp_b
+  |> Binding.qualify true (Binding.name_of fp_b);
+fun mk_version_binding version = Binding.qualify false ("v" ^ string_of_int version);
+fun mk_version_fp_binding internal ctxt =
+  mk_internal internal ctxt Binding.concealed ooo (mk_fp_binding oo mk_version_binding);
+(*FIXME: get rid of ugly names when typedef and primrec respect qualification*)
+fun mk_version_binding_ugly version = Binding.suffix_name ("_v" ^ string_of_int version);
+fun mk_version_fp_binding_ugly internal ctxt version fp_b pre =
+  Binding.prefix_name (pre ^ "_") fp_b
+  |> mk_version_binding_ugly version
+  |> mk_internal internal ctxt Binding.concealed;
+
+fun mk_mapN ctxt live_AsBs TA bnf =
+  let val TB = Term.typ_subst_atomic live_AsBs TA in
+    enforce_type ctxt (snd o strip_typeN (length live_AsBs)) (TA --> TB) (map_of_bnf bnf)
+  end;
+
+fun mk_relN ctxt live_AsBs TA bnf =
+  let val TB = Term.typ_subst_atomic live_AsBs TA in
+    enforce_type ctxt (snd o strip_typeN (length live_AsBs)) (mk_pred2T TA TB) (rel_of_bnf bnf)
+  end;
+
+fun mk_map1 ctxt Y Z = mk_mapN ctxt [(Y, Z)];
+fun mk_rel1 ctxt Y Z = mk_relN ctxt [(Y, Z)];
+
+fun define_const internal fp_b version name rhs lthy =
+  let
+    val b = mk_version_fp_binding internal lthy version fp_b name;
+
+    val ((free, (_, def_free)), (lthy, lthy_old)) = lthy
+      |> Local_Theory.open_target |> snd
+      |> Local_Theory.define ((b, NoSyn), ((Thm.def_binding b |> Binding.concealed, []), rhs))
+      ||> `Local_Theory.close_target;
+
+    val phi = Proof_Context.export_morphism lthy_old lthy;
+
+    val const = Morphism.term phi free;
+    val const' = enforce_type lthy I (fastype_of free) const;
+  in
+    ((const', Morphism.thm phi def_free), lthy)
+  end;
+
+fun define_single_primrec b eqs lthy =
+  let
+    val (([free], [def_free], [simps_free]), (lthy, lthy_old)) = lthy
+      |> Local_Theory.open_target |> snd
+      |> Local_Theory.map_background_naming (mk_internal true lthy Name_Space.concealed) (*TODO check*)
+      |> primrec [(b, NONE, NoSyn)] (map (pair Attrib.empty_binding) eqs)
+      ||> `Local_Theory.close_target;
+
+    val phi = Proof_Context.export_morphism lthy_old lthy;
+
+    val const = Morphism.term phi free;
+    val const' = enforce_type lthy I (fastype_of free) const;
+  in
+    ((const', Morphism.thm phi def_free, map (Morphism.thm phi) simps_free), lthy)
+  end;
+
+type buffer =
+  {Oper: term,
+   VLeaf: term,
+   CLeaf: term,
+   ctr_wrapper: term,
+   friends: (typ * term) Symtab.table};
+
+fun map_buffer f {Oper, VLeaf, CLeaf, ctr_wrapper, friends} =
+  {Oper = f Oper, VLeaf = f VLeaf, CLeaf = f CLeaf, ctr_wrapper = f ctr_wrapper,
+   friends = Symtab.map (K (apsnd f)) friends};
+
+fun morph_buffer phi = map_buffer (Morphism.term phi);
+
+fun specialize_buffer_types {Oper, VLeaf, CLeaf, ctr_wrapper, friends} =
+  let
+    val ssig_T as Type (_, Ts) = body_type (fastype_of VLeaf);
+    val Y = List.last Ts;
+    val ssigifyT = substT Y ssig_T;
+  in
+    {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = ssigifyT ctr_wrapper,
+     friends = Symtab.map (K (apsnd ssigifyT)) friends}
+  end;
+
+type dtor_coinduct_info =
+  {dtor_coinduct: thm,
+   cong_def: thm,
+   cong_locale: thm,
+   cong_base: thm,
+   cong_refl: thm,
+   cong_sym: thm,
+   cong_trans: thm,
+   cong_alg_intros: thm list};
+
+fun map_dtor_coinduct_info f {dtor_coinduct, cong_def, cong_locale, cong_base, cong_refl, cong_sym,
+    cong_trans, cong_alg_intros} =
+  {dtor_coinduct = f dtor_coinduct, cong_def = f cong_def, cong_locale = f cong_locale,
+   cong_base = f cong_base, cong_refl = f cong_refl, cong_sym = f cong_sym,
+   cong_trans = f cong_trans, cong_alg_intros = map f cong_alg_intros};
+
+fun morph_dtor_coinduct_info phi = map_dtor_coinduct_info (Morphism.thm phi);
+
+type corec_ad =
+  {fpT: typ,
+   friend_names: string list};
+
+fun morph_corec_ad phi {fpT, friend_names} =
+  {fpT = Morphism.typ phi fpT, friend_names = friend_names};
+
+type corec_info =
+  {fp_b: binding,
+   version: int,
+   fpT: typ,
+   Y: typ,
+   Z: typ,
+   friend_names: string list,
+   sig_fp_sugars: fp_sugar list,
+   ssig_fp_sugar: fp_sugar,
+   Lam: term,
+   proto_sctr: term,
+   flat: term,
+   eval_core: term,
+   eval: term,
+   algLam: term,
+   corecUU: term,
+   dtor_transfer: thm,
+   Lam_transfer: thm,
+   Lam_pointful_natural: thm,
+   proto_sctr_transfer: thm,
+   flat_simps: thm list,
+   eval_core_simps: thm list,
+   eval_thm: thm,
+   eval_simps: thm list,
+   all_algLam_algs: thm list,
+   algLam_thm: thm,
+   dtor_algLam: thm,
+   corecUU_thm: thm,
+   corecUU_unique: thm,
+   corecUU_transfer: thm,
+   buffer: buffer,
+   all_dead_k_bnfs: BNF_Def.bnf list,
+   Retr: term,
+   equivp_Retr: thm,
+   Retr_coinduct: thm,
+   dtor_coinduct_info: dtor_coinduct_info};
+
+fun morph_corec_info phi
+    ({fp_b, version, fpT, Y, Z, friend_names, sig_fp_sugars, ssig_fp_sugar, Lam, proto_sctr, flat,
+      eval_core, eval, algLam, corecUU, dtor_transfer, Lam_transfer, Lam_pointful_natural,
+      proto_sctr_transfer, flat_simps, eval_core_simps, eval_thm, eval_simps, all_algLam_algs,
+      algLam_thm, dtor_algLam, corecUU_thm, corecUU_unique, corecUU_transfer, buffer,
+      all_dead_k_bnfs, Retr, equivp_Retr, Retr_coinduct, dtor_coinduct_info} : corec_info) =
+  {fp_b = fp_b, version = version, fpT = Morphism.typ phi fpT, Y = Morphism.typ phi Y,
+   Z = Morphism.typ phi Z, friend_names = friend_names, sig_fp_sugars = sig_fp_sugars (*no morph*),
+   ssig_fp_sugar = ssig_fp_sugar (*no morph*), Lam = Morphism.term phi Lam,
+   proto_sctr = Morphism.term phi proto_sctr, flat = Morphism.term phi flat,
+   eval_core = Morphism.term phi eval_core, eval = Morphism.term phi eval,
+   algLam = Morphism.term phi algLam, corecUU = Morphism.term phi corecUU,
+   dtor_transfer = dtor_transfer, Lam_transfer = Morphism.thm phi Lam_transfer,
+   Lam_pointful_natural = Morphism.thm phi Lam_pointful_natural,
+   proto_sctr_transfer = Morphism.thm phi proto_sctr_transfer,
+   flat_simps = map (Morphism.thm phi) flat_simps,
+   eval_core_simps = map (Morphism.thm phi) eval_core_simps, eval_thm = Morphism.thm phi eval_thm,
+   eval_simps = map (Morphism.thm phi) eval_simps,
+   all_algLam_algs = map (Morphism.thm phi) all_algLam_algs,
+   algLam_thm = Morphism.thm phi algLam_thm, dtor_algLam = Morphism.thm phi dtor_algLam,
+   corecUU_thm = Morphism.thm phi corecUU_thm, corecUU_unique = Morphism.thm phi corecUU_unique,
+   corecUU_transfer = Morphism.thm phi corecUU_transfer, buffer = morph_buffer phi buffer,
+   all_dead_k_bnfs = map (morph_bnf phi) all_dead_k_bnfs, Retr = Morphism.term phi Retr,
+   equivp_Retr = Morphism.thm phi equivp_Retr, Retr_coinduct = Morphism.thm phi Retr_coinduct,
+   dtor_coinduct_info = morph_dtor_coinduct_info phi dtor_coinduct_info};
+
+datatype ('a, 'b) expr =
+  Ad of 'a * (local_theory -> 'b * local_theory) |
+  Info of 'b;
+
+fun is_Ad (Ad _) = true
+  | is_Ad _ = false;
+
+fun is_Info (Info _) = true
+  | is_Info _ = false;
+
+type corec_info_expr = (corec_ad, corec_info) expr;
+
+fun morph_corec_info_expr phi (Ad (ad, f)) = Ad (morph_corec_ad phi ad, f)
+  | morph_corec_info_expr phi (Info info) = Info (morph_corec_info phi info);
+
+val transfer_corec_info_expr = morph_corec_info_expr o Morphism.transfer_morphism;
+
+type corec_data = int Symtab.table * corec_info_expr list Symtab.table list;
+
+structure Data = Generic_Data
+(
+  type T = corec_data;
+  val empty = (Symtab.empty, [Symtab.empty]);
+  val extend = I;
+  fun merge ((version_tab1, info_tabs1), (version_tab2, info_tabs2)) : T =
+    (Symtab.join (K Int.max) (version_tab1, version_tab2), info_tabs1 @ info_tabs2);
+);
+
+fun corec_ad_of_expr (Ad (ad, _)) = ad
+  | corec_ad_of_expr (Info {fpT, friend_names, ...}) = {fpT = fpT, friend_names = friend_names};
+
+fun corec_info_exprs_of_generic context fpT_name =
+  let
+    val thy = Context.theory_of context;
+    val info_tabs = snd (Data.get context);
+  in
+    maps (fn info_tab => these (Symtab.lookup info_tab fpT_name)) info_tabs
+    |> map (transfer_corec_info_expr thy)
+  end;
+
+val corec_info_exprs_of = corec_info_exprs_of_generic o Context.Proof;
+
+val keep_corec_infos = map_filter (fn Ad _ => NONE | Info info => SOME info);
+
+val corec_infos_of_generic = keep_corec_infos oo corec_info_exprs_of_generic;
+val corec_infos_of = keep_corec_infos oo corec_info_exprs_of;
+
+fun str_of_corec_ad ctxt {fpT, friend_names} =
+  "[" ^ Syntax.string_of_typ ctxt fpT ^ "; " ^ commas friend_names ^ "]";
+
+fun str_of_corec_info ctxt {fpT, version, friend_names, ...} =
+  "{" ^ Syntax.string_of_typ ctxt fpT ^ "; " ^ commas friend_names ^ "; v" ^ string_of_int version ^
+  "}";
+
+fun str_of_corec_info_expr ctxt (Ad (ad, _)) = str_of_corec_ad ctxt ad
+  | str_of_corec_info_expr ctxt (Info info) = str_of_corec_info ctxt info;
+
+fun print_corec_infos ctxt =
+  Symtab.fold (fn (fpT_name, exprs) => fn () =>
+      writeln (fpT_name ^ ":\n" ^
+        cat_lines (map (prefix "  " o str_of_corec_info_expr ctxt) exprs)))
+    (the_single (snd (Data.get (Context.Proof ctxt)))) ();
+
+val has_no_corec_info = null oo corec_info_exprs_of;
+
+fun get_name_next_version_of fpT_name ctxt =
+  let
+    val (version_tab, info_tabs) = Data.get (Context.Theory (Proof_Context.theory_of ctxt));
+    val fp_base = Long_Name.base_name fpT_name;
+    val fp_b = Binding.name fp_base;
+    val version_tab' = Symtab.map_default (fp_base, ~1) (Integer.add 1) version_tab;
+    val SOME version = Symtab.lookup version_tab' fp_base;
+    val ctxt' = ctxt
+      |> Local_Theory.background_theory (Context.theory_map (Data.put (version_tab', info_tabs)));
+  in
+    ((fp_b, version), ctxt')
+  end;
+
+type friend_info =
+  {algrho: term,
+   dtor_algrho: thm,
+   algLam_algrho: thm};
+
+fun morph_friend_info phi ({algrho, dtor_algrho, algLam_algrho} : friend_info) =
+  {algrho = Morphism.term phi algrho, dtor_algrho = Morphism.thm phi dtor_algrho,
+   algLam_algrho = Morphism.thm phi algLam_algrho};
+
+fun checked_fp_sugar_of ctxt fpT_name =
+  let
+    val fp_sugar as {X, fp_res = {Ts = fpTs, ...}, fp_ctr_sugar = {ctrXs_Tss, ...}, ...} =
+      (case fp_sugar_of ctxt fpT_name of
+        SOME (fp_sugar as {fp = Greatest_FP, ...}) => fp_sugar
+      | _ => not_codatatype ctxt (Type (fpT_name, [] (*yuck*))));
+
+    val _ =
+      if length fpTs > 1 then
+        mutual_codatatype ()
+      else if not (exists (exists (Term.exists_subtype (curry (op =) X))) ctrXs_Tss) then
+        noncorecursive_codatatype ()
+      else if ctrXs_Tss = [[X]] then
+        singleton_codatatype ctxt
+      else
+        ();
+  in
+    fp_sugar
+  end;
+
+fun inline_pre_bnfs f lthy =
+  lthy
+  |> Config.put typedef_threshold ~1
+  |> f
+  |> Config.put typedef_threshold (Config.get lthy typedef_threshold);
+
+fun bnf_kill_all_but nn bnf lthy =
+  ((empty_comp_cache, empty_unfolds), lthy)
+  |> kill_bnf I (live_of_bnf bnf - nn) bnf
+  ||> snd;
+
+fun bnf_with_deads_and_lives dead_Es live_As Y fpT T lthy =
+   let
+     val qsoty = quote o Syntax.string_of_typ lthy;
+
+     val unfreeze_fp = Tsubst Y fpT;
+
+    fun flatten_tyargs Ass =
+      map dest_TFree live_As
+      |> filter (fn T => exists (fn Ts => member (op =) Ts T) Ass);
+
+     val ((bnf, _), (_, lthy)) =
+      bnf_of_typ false Do_Inline I flatten_tyargs [Term.dest_TFree Y]
+        (map Term.dest_TFree dead_Es) T ((empty_comp_cache, empty_unfolds), lthy)
+      handle BAD_DEAD (Y, Y_backdrop) =>
+        (case Y_backdrop of
+          Type (bad_tc, _) =>
+          let
+            val T = qsoty (unfreeze_fp Y);
+            val T_backdrop = qsoty (unfreeze_fp Y_backdrop);
+            fun register_hint () =
+              "\nUse the " ^ quote (#1 @{command_keyword "bnf"}) ^ " command to register " ^
+              quote bad_tc ^ " as a bounded natural functor to allow nested (co)recursion through \
+              \it";
+          in
+            if is_some (bnf_of lthy bad_tc) orelse is_some (fp_sugar_of lthy bad_tc) then
+              error ("Inadmissible occurrence of type " ^ T ^ " in type expression " ^
+                T_backdrop)
+            else
+              error ("Unsupported occurrence of type " ^ T ^ " via type constructor " ^
+                quote bad_tc ^ " in type expression " ^ T_backdrop ^ register_hint ())
+          end);
+
+    val phi =
+      Morphism.term_morphism "BNF" (Raw_Simplifier.rewrite_term (Proof_Context.theory_of lthy)
+        @{thms BNF_Composition.id_bnf_def} [])
+      $> Morphism.thm_morphism "BNF" (unfold_thms lthy @{thms BNF_Composition.id_bnf_def});
+  in
+    (morph_bnf phi bnf, lthy)
+  end;
+
+fun define_sig_type fp_b version fp_alives Es Y rhsT lthy =
+  let
+    val T_b = mk_version_fp_binding_ugly true lthy version fp_b sigN;
+    val ctr_b = mk_version_fp_binding false lthy version fp_b SigN;
+    val sel_b = mk_version_fp_binding true lthy version fp_b unsigN;
+
+    val lthy = Local_Theory.open_target lthy |> snd;
+
+    val T_name = Local_Theory.full_name lthy T_b;
+
+    val tyargs = map2 (fn alive => pair (if alive then SOME Binding.empty else NONE)
+      o rpair @{sort type}) (fp_alives @ [true]) (Es @ [Y]);
+    val ctr_specs = [(((Binding.empty, ctr_b), [(sel_b, rhsT)]), NoSyn)];
+    val spec = (((((tyargs, T_b), NoSyn), ctr_specs),
+      (Binding.empty, Binding.empty, Binding.empty)), []);
+
+    val plugins = Plugin_Name.make_filter lthy (K (curry (op =) transfer_plugin));
+    val discs_sels = true;
+
+    val lthy = lthy
+      |> Local_Theory.map_background_naming (mk_internal true lthy Name_Space.concealed) (*TODO check*)
+      |> inline_pre_bnfs (co_datatypes Least_FP construct_lfp ((plugins, discs_sels), [spec]))
+      |> Local_Theory.close_target;
+
+    val SOME fp_sugar = fp_sugar_of lthy T_name;
+  in
+    (fp_sugar, lthy)
+  end;
+
+fun define_ssig_type fp_b version fp_alives Es Y fpT lthy =
+  let
+    val sig_T_b = mk_version_fp_binding_ugly true lthy version fp_b sigN;
+    val T_b = Binding.prefix_name s_prefix sig_T_b;
+    val Oper_b = mk_version_fp_binding false lthy version fp_b OperN;
+    val VLeaf_b = mk_version_fp_binding false lthy version fp_b VLeafN;
+    val CLeaf_b = mk_version_fp_binding false lthy version fp_b CLeafN;
+
+    val lthy = Local_Theory.open_target lthy |> snd;
+
+    val sig_T_name = Local_Theory.full_name lthy sig_T_b;
+    val T_name = Long_Name.map_base_name (prefix s_prefix) sig_T_name;
+
+    val As = Es @ [Y];
+    val ssig_sig_T = Type (sig_T_name, Es @ [Type (T_name, As)]);
+
+    val tyargs = map2 (fn alive => pair (if alive then SOME Binding.empty else NONE)
+      o rpair @{sort type}) (fp_alives @ [true]) As;
+    val ctr_specs =
+      [(((Binding.empty, Oper_b), [(Binding.empty, ssig_sig_T)]), NoSyn),
+       (((Binding.empty, VLeaf_b), [(Binding.empty, Y)]), NoSyn),
+       (((Binding.empty, CLeaf_b), [(Binding.empty, fpT)]), NoSyn)];
+    val spec = (((((tyargs, T_b), NoSyn), ctr_specs),
+      (Binding.empty, Binding.empty, Binding.empty)), []);
+
+    val plugins = Plugin_Name.make_filter lthy (K (curry (op =) transfer_plugin));
+    val discs_sels = false;
+
+    val lthy = lthy
+      |> Local_Theory.map_background_naming (mk_internal true lthy Name_Space.concealed) (*TODO check*)
+      |> inline_pre_bnfs (co_datatypes Least_FP construct_lfp ((plugins, discs_sels), [spec]))
+      |> Local_Theory.close_target;
+
+    val SOME fp_sugar = fp_sugar_of lthy T_name;
+  in
+    (fp_sugar, lthy)
+  end;
+
+fun embed_Sig ctxt Sig inl_or_r t =
+  Library.foldl1 HOLogic.mk_comp [Sig, inl_or_r, dummify_atomic_types t]
+  |> Syntax.check_term ctxt;
+
+fun mk_ctr_wrapper_friends ctxt friend_name friend_T old_sig_T k_T Sig old_buffer =
+  let
+    val embed_Sig_inl = embed_Sig ctxt Sig (Inl_const old_sig_T k_T);
+
+    val ctr_wrapper = embed_Sig_inl (#ctr_wrapper old_buffer);
+    val friends = Symtab.map (K (apsnd embed_Sig_inl)) (#friends old_buffer)
+      |> Symtab.update_new (friend_name, (friend_T,
+        HOLogic.mk_comp (Sig, Inr_const old_sig_T k_T)));
+  in
+    (ctr_wrapper, friends)
+  end;
+
+fun pre_type_of_ctor Y ctor =
+  let
+    val (fp_preT, fpT) = dest_funT (fastype_of ctor);
+  in
+    typ_subst_nonatomic [(fpT, Y)] fp_preT
+  end;
+
+fun mk_k_as_ssig Z old_sig_T k_T ssig_T Sig dead_sig_map Oper VLeaf =
+  let
+    val inr' = Inr_const old_sig_T k_T;
+    val dead_sig_map' = substT Z ssig_T dead_sig_map;
+  in
+    Library.foldl1 HOLogic.mk_comp [Oper, dead_sig_map' $ VLeaf, Sig, inr']
+  end;
+
+fun define_embL name fp_b version Y Z fpT old_sig_T old_ssig_T other_summand_T ssig_T Inl_or_r_const
+    dead_old_sig_map Sig old_Oper old_VLeaf old_CLeaf Oper VLeaf CLeaf lthy =
+  let
+    val embL_b = mk_version_fp_binding true lthy version fp_b name;
+    val old_ssig_old_sig_T = Tsubst Y old_ssig_T old_sig_T;
+    val ssig_old_sig_T = Tsubst Y ssig_T old_sig_T;
+    val ssig_other_summand_T = Tsubst Y ssig_T other_summand_T;
+
+    val sigx = Var (("s", 0), old_ssig_old_sig_T);
+    val x = Var (("x", 0), Y);
+    val j = Var (("j", 0), fpT);
+    val embL = Free (Binding.name_of embL_b, old_ssig_T --> ssig_T);
+    val dead_old_sig_map' = Term.subst_atomic_types [(Y, old_ssig_T), (Z, ssig_T)] dead_old_sig_map;
+    val Sig' = substT Y ssig_T Sig;
+    val inl' = Inl_or_r_const ssig_old_sig_T ssig_other_summand_T;
+
+    val Oper_eq = mk_Trueprop_eq (embL $ (old_Oper $ sigx),
+        Oper $ (Sig' $ (inl' $ (dead_old_sig_map' $ embL $ sigx))))
+      |> Logic.all sigx;
+    val VLeaf_eq = mk_Trueprop_eq (embL $ (old_VLeaf $ x), VLeaf $ x)
+      |> Logic.all x;
+    val CLeaf_eq = mk_Trueprop_eq (embL $ (old_CLeaf $ j), CLeaf $ j)
+      |> Logic.all j;
+  in
+    define_single_primrec embL_b [Oper_eq, VLeaf_eq, CLeaf_eq] lthy
+  end;
+
+fun define_Lam_base fp_b version Y Z preT ssig_T dead_pre_map Sig unsig dead_sig_map Oper VLeaf
+    lthy =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+
+    val snd' = snd_const YpreT;
+    val dead_pre_map' = substT Z ssig_T dead_pre_map;
+    val Sig' = substT Y ssig_T Sig;
+    val unsig' = substT Y ssig_T unsig;
+    val dead_sig_map' = Term.subst_atomic_types [(Y, YpreT), (Z, ssig_T)] dead_sig_map;
+
+    val rhs = HOLogic.mk_comp (unsig', dead_sig_map'
+      $ Library.foldl1 HOLogic.mk_comp [Oper, Sig', dead_pre_map' $ VLeaf, snd']);
+  in
+    define_const true fp_b version LamN rhs lthy
+  end;
+
+fun define_Lam_step_or_merge fp_b version Y preT unsig left_case right_case lthy =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+
+    val unsig' = substT Y YpreT unsig;
+
+    val rhs = HOLogic.mk_comp (mk_case_sum (left_case, right_case), unsig');
+  in
+    define_const true fp_b version LamN rhs lthy
+  end;
+
+fun define_Lam_step fp_b version Y Z preT old_ssig_T ssig_T dead_pre_map unsig rho embL old_Lam
+    lthy =
+  let
+    val dead_pre_map' = Term.subst_atomic_types [(Y, old_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val left_case = HOLogic.mk_comp (dead_pre_map' $ embL, old_Lam);
+  in
+    define_Lam_step_or_merge fp_b version Y preT unsig left_case rho lthy
+  end;
+
+fun define_Lam_merge fp_b version Y Z preT old1_ssig_T old2_ssig_T ssig_T dead_pre_map unsig embLL
+    embLR old1_Lam old2_Lam lthy =
+  let
+    val dead_pre_map' = Term.subst_atomic_types [(Y, old1_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val dead_pre_map'' = Term.subst_atomic_types [(Y, old2_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val left_case = HOLogic.mk_comp (dead_pre_map' $ embLL, old1_Lam);
+    val right_case = HOLogic.mk_comp (dead_pre_map'' $ embLR, old2_Lam);
+  in
+    define_Lam_step_or_merge fp_b version Y preT unsig left_case right_case lthy
+  end;
+
+fun define_proto_sctr_step_or_merge fp_b version old_sig_T right_T Sig old_proto_sctr =
+  let
+    val rhs = Library.foldl1 HOLogic.mk_comp [Sig, Inl_const old_sig_T right_T, old_proto_sctr];
+  in
+    define_const true fp_b version proto_sctrN rhs
+  end;
+
+fun define_flat fp_b version Y Z fpT sig_T ssig_T Oper VLeaf CLeaf dead_sig_map lthy =
+  let
+    val flat_b = mk_version_fp_binding true lthy version fp_b flatN;
+    val ssig_sig_T = Tsubst Y ssig_T sig_T;
+    val ssig_ssig_sig_T = Tsubst Y ssig_T ssig_sig_T;
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T;
+
+    val sigx = Var (("s", 0), ssig_ssig_sig_T);
+    val x = Var (("x", 0), ssig_T);
+    val j = Var (("j", 0), fpT);
+    val flat = Free (Binding.name_of flat_b, ssig_ssig_T --> ssig_T);
+    val Oper' = substT Y ssig_T Oper;
+    val VLeaf' = substT Y ssig_T VLeaf;
+    val CLeaf' = substT Y ssig_T CLeaf;
+    val dead_sig_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_sig_map;
+
+    val Oper_eq = mk_Trueprop_eq (flat $ (Oper' $ sigx), Oper $ (dead_sig_map' $ flat $ sigx))
+      |> Logic.all sigx;
+    val VLeaf_eq = mk_Trueprop_eq (flat $ (VLeaf' $ x), x)
+      |> Logic.all x;
+    val CLeaf_eq = mk_Trueprop_eq (flat $ (CLeaf' $ j), CLeaf $ j)
+      |> Logic.all j;
+  in
+    define_single_primrec flat_b [Oper_eq, VLeaf_eq, CLeaf_eq] lthy
+  end;
+
+fun define_eval_core fp_b version Y Z preT fpT sig_T ssig_T dtor Oper VLeaf CLeaf dead_pre_map
+    dead_sig_map dead_ssig_map flat Lam lthy =
+  let
+    val eval_core_b = mk_version_fp_binding true lthy version fp_b eval_coreN;
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val Ypre_ssig_T = Tsubst Y YpreT ssig_T;
+    val Ypre_ssig_sig_T = Tsubst Y Ypre_ssig_T sig_T;
+    val ssig_preT = Tsubst Y ssig_T preT;
+    val ssig_YpreT = Tsubst Y ssig_T YpreT;
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T;
+
+    val sigx = Var (("s", 0), Ypre_ssig_sig_T);
+    val x = Var (("x", 0), YpreT);
+    val j = Var (("j", 0), fpT);
+    val eval_core = Free (Binding.name_of eval_core_b, Ypre_ssig_T --> ssig_preT);
+    val Oper' = substT Y YpreT Oper;
+    val VLeaf' = substT Y YpreT VLeaf;
+    val CLeaf' = substT Y YpreT CLeaf;
+    val dead_pre_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val dead_pre_map'' = substT Z ssig_T dead_pre_map;
+    val dead_pre_map''' = Term.subst_atomic_types [(Y, fpT), (Z, ssig_T)] dead_pre_map;
+    val dead_sig_map' = Term.subst_atomic_types [(Y, Ypre_ssig_T), (Z, ssig_YpreT)] dead_sig_map;
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, YpreT), (Z, Y)] dead_ssig_map;
+    val Lam' = substT Y ssig_T Lam;
+    val fst' = fst_const YpreT;
+    val snd' = snd_const YpreT;
+
+    val Oper_eq = mk_Trueprop_eq (eval_core $ (Oper' $ sigx),
+        dead_pre_map' $ flat $ (Lam' $ (dead_sig_map' $ (Abs (Name.uu, Ypre_ssig_T,
+          HOLogic.mk_prod (dead_ssig_map' $ fst' $ Bound 0, eval_core $ Bound 0))) $ sigx)))
+      |> Logic.all sigx;
+    val VLeaf_eq = mk_Trueprop_eq (eval_core $ (VLeaf' $ x), dead_pre_map'' $ VLeaf $ (snd' $ x))
+      |> Logic.all x;
+    val CLeaf_eq = mk_Trueprop_eq (eval_core $ (CLeaf' $ j), dead_pre_map''' $ CLeaf $ (dtor $ j))
+      |> Logic.all j;
+  in
+    define_single_primrec eval_core_b [Oper_eq, VLeaf_eq, CLeaf_eq] lthy
+  end;
+
+fun define_eval fp_b version Y Z preT fpT ssig_T dtor dtor_unfold dead_ssig_map eval_core lthy =
+  let
+    val fp_preT = Tsubst Y fpT preT;
+    val fppreT = HOLogic.mk_prodT (fpT, fp_preT);
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val dtor_unfold' = substT Z fp_ssig_T dtor_unfold;
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, fpT), (Z, fppreT)] dead_ssig_map;
+    val eval_core' = substT Y fpT eval_core;
+    val id' = HOLogic.id_const fpT;
+
+    val rhs = dtor_unfold' $ HOLogic.mk_comp (eval_core', dead_ssig_map' $ mk_convol (id', dtor));
+  in
+    define_const true fp_b version evalN rhs lthy
+  end;
+
+fun define_cutSsig fp_b version Y Z preT ssig_T dead_pre_map VLeaf dead_ssig_map flat eval_core
+    lthy =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T;
+    val ssig_ssig_preT = HOLogic.mk_prodT (ssig_T, ssig_preT);
+
+    val h = Var (("h", 0), Y --> ssig_preT);
+    val dead_pre_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val dead_ssig_map' = substT Z ssig_ssig_preT dead_ssig_map;
+    val eval_core' = substT Y ssig_T eval_core;
+
+    val rhs = Library.foldl1 HOLogic.mk_comp [dead_pre_map' $ flat, eval_core',
+        dead_ssig_map' $ mk_convol (VLeaf, h)]
+      |> Term.lambda h;
+  in
+    define_const true fp_b version cutSsigN rhs lthy
+  end;
+
+fun define_algLam fp_b version Y Z fpT ssig_T Oper VLeaf dead_sig_map eval lthy =
+  let
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val Oper' = substT Y fpT Oper;
+    val VLeaf' = substT Y fpT VLeaf;
+    val dead_sig_map' = Term.subst_atomic_types [(Y, fpT), (Z, fp_ssig_T)] dead_sig_map;
+
+    val rhs = Library.foldl1 HOLogic.mk_comp [eval, Oper', dead_sig_map' $ VLeaf'];
+  in
+    define_const true fp_b version algLamN rhs lthy
+  end;
+
+fun define_corecU fp_b version Y Z preT ssig_T dtor_unfold VLeaf cutSsig lthy =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+
+    val h = Var (("h", 0), Y --> ssig_preT);
+    val dtor_unfold' = substT Z ssig_T dtor_unfold;
+
+    val rhs = HOLogic.mk_comp (dtor_unfold' $ (cutSsig $ h), VLeaf)
+      |> Term.lambda h;
+  in
+    define_const true fp_b version corecUN rhs lthy
+  end;
+
+fun define_corecUU fp_b version Y Z preT ssig_T dead_pre_map dead_ssig_map flat eval_core sctr
+    corecU lthy =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T
+    val ssig_ssig_preT = HOLogic.mk_prodT (ssig_T, ssig_preT);
+
+    val ssig_pre_ssig_T = Tsubst Y ssig_preT ssig_T;
+
+    val h = Var (("h", 0), Y --> ssig_pre_ssig_T);
+    val dead_pre_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val eval_core' = substT Y ssig_T eval_core;
+    val dead_ssig_map' =
+      Term.subst_atomic_types [(Y, ssig_preT), (Z, ssig_ssig_preT)] dead_ssig_map;
+    val id' = HOLogic.id_const ssig_preT;
+
+    val rhs = corecU $ Library.foldl1 HOLogic.mk_comp
+        [dead_pre_map' $ flat, eval_core', dead_ssig_map' $ mk_convol (sctr, id'), h]
+      |> Term.lambda h;
+  in
+    define_const true fp_b version corecUUN rhs lthy
+  end;
+
+fun derive_sig_transfer maybe_swap ctxt live_AsBs pre_rel sig_rel Rs R const pre_rel_def
+    preT_rel_eqs transfer_thm =
+  let
+    val RRpre_rel = list_comb (pre_rel, Rs) $ R;
+    val RRsig_rel = list_comb (sig_rel, Rs) $ R;
+    val constB = Term.subst_atomic_types live_AsBs const;
+
+    val goal = uncurry mk_rel_fun (maybe_swap (RRpre_rel, RRsig_rel)) $ const $ constB
+      |> HOLogic.mk_Trueprop;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_sig_transfer_tac ctxt pre_rel_def preT_rel_eqs transfer_thm))
+    |> Thm.close_derivation
+  end;
+
+fun derive_transfer_by_transfer_prover ctxt live_AsBs Rs R const const_defs rel_eqs transfers =
+  let
+    val constB = Term.subst_atomic_types live_AsBs const;
+    val goal = mk_parametricity_goal ctxt (Rs @ [R]) const constB;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_transfer_by_transfer_prover_tac ctxt (const_defs @ map (fn thm => thm RS sym) rel_eqs)
+        rel_eqs transfers))
+    |> Thm.close_derivation
+  end;
+
+fun derive_dtor_transfer ctxt live_EsFs Y Z pre_rel fp_rel Rs dtor dtor_rel_thm =
+  let
+    val Type (@{type_name fun}, [fpT, Type (@{type_name fun}, [fpTB, @{typ bool}])]) =
+      snd (strip_typeN (length live_EsFs) (fastype_of fp_rel));
+
+    val pre_rel' = Term.subst_atomic_types [(Y, fpT), (Z, fpTB)] pre_rel;
+    val Rpre_rel = list_comb (pre_rel', Rs);
+    val Rfp_rel = list_comb (fp_rel, Rs);
+    val dtorB = Term.subst_atomic_types live_EsFs dtor;
+
+    val goal = HOLogic.mk_Trueprop (mk_rel_fun Rfp_rel (Rpre_rel $ Rfp_rel) $ dtor $ dtorB);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_dtor_transfer_tac ctxt dtor_rel_thm))
+    |> Thm.close_derivation
+  end;
+
+fun derive_Lam_or_eval_core_transfer ctxt live_AsBs Y Z preT ssig_T Rs R pre_rel sig_or_ssig_rel
+    ssig_rel const const_def rel_eqs transfers =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val ZpreTB = typ_subst_atomic live_AsBs YpreT;
+    val ssig_TB = typ_subst_atomic live_AsBs ssig_T;
+
+    val pre_rel' = Term.subst_atomic_types [(Y, ssig_T), (Z, ssig_TB)] pre_rel;
+    val sig_or_ssig_rel' = Term.subst_atomic_types [(Y, YpreT), (Z, ZpreTB)] sig_or_ssig_rel;
+    val Rsig_or_ssig_rel' = list_comb (sig_or_ssig_rel', Rs);
+    val RRpre_rel = list_comb (pre_rel, Rs) $ R;
+    val RRssig_rel = list_comb (ssig_rel, Rs) $ R;
+    val Rpre_rel' = list_comb (pre_rel', Rs);
+    val constB = subst_atomic_types live_AsBs const;
+
+    val goal = mk_rel_fun (Rsig_or_ssig_rel' $ mk_rel_prod R RRpre_rel) (Rpre_rel' $ RRssig_rel)
+        $ const $ constB
+      |> HOLogic.mk_Trueprop;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_transfer_by_transfer_prover_tac ctxt [const_def] rel_eqs transfers))
+    |> Thm.close_derivation
+  end;
+
+fun derive_proto_sctr_transfer_step_or_merge ctxt Y Z R dead_pre_rel dead_sig_rel proto_sctr
+    proto_sctr_def fp_k_T_rel_eqs transfers =
+  let
+    val proto_sctrZ = substT Y Z proto_sctr;
+    val goal = mk_rel_fun (dead_pre_rel $ R) (dead_sig_rel $ R) $ proto_sctr $ proto_sctrZ
+      |> HOLogic.mk_Trueprop;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_transfer_by_transfer_prover_tac ctxt [proto_sctr_def] fp_k_T_rel_eqs transfers))
+    |> Thm.close_derivation
+  end;
+
+fun derive_sctr_transfer ctxt live_AsBs Y Z ssig_T Rs R pre_rel ssig_rel sctr sctr_def
+    fp_k_T_rel_eqs transfers =
+  let
+    val ssig_TB = typ_subst_atomic live_AsBs ssig_T;
+
+    val pre_rel' = Term.subst_atomic_types [(Y, ssig_T), (Z, ssig_TB)] pre_rel;
+    val Rpre_rel' = list_comb (pre_rel', Rs);
+    val RRssig_rel = list_comb (ssig_rel, Rs) $ R;
+    val sctrB = subst_atomic_types live_AsBs sctr;
+
+    val goal = HOLogic.mk_Trueprop (mk_rel_fun (Rpre_rel' $ RRssig_rel) RRssig_rel $ sctr $ sctrB);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_transfer_by_transfer_prover_tac ctxt [sctr_def] fp_k_T_rel_eqs transfers))
+    |> Thm.close_derivation
+  end;
+
+fun derive_corecUU_transfer ctxt live_AsBs Y Z Rs R preT ssig_T pre_rel fp_rel ssig_rel corecUU
+    cutSsig_def corecU_def corecUU_def fp_k_T_rel_eqs transfers =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+    val ssig_TB = typ_subst_atomic live_AsBs ssig_T;
+    val ssig_preTB = typ_subst_atomic live_AsBs ssig_preT;
+
+    val pre_rel' = Term.subst_atomic_types [(Y, ssig_T), (Z, ssig_TB)] pre_rel;
+    val ssig_rel' = Term.subst_atomic_types [(Y, ssig_preT), (Z, ssig_preTB)] ssig_rel;
+    val Rpre_rel' = list_comb (pre_rel', Rs);
+    val Rfp_rel = list_comb (fp_rel, Rs);
+    val RRssig_rel = list_comb (ssig_rel, Rs) $ R;
+    val Rssig_rel' = list_comb (ssig_rel', Rs);
+    val corecUUB = subst_atomic_types live_AsBs corecUU;
+
+    val goal = mk_rel_fun (mk_rel_fun R (Rssig_rel' $ (Rpre_rel' $ RRssig_rel)))
+        (mk_rel_fun R Rfp_rel) $ corecUU $ corecUUB
+      |> HOLogic.mk_Trueprop;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_transfer_by_transfer_prover_tac ctxt [cutSsig_def, corecU_def, corecUU_def] fp_k_T_rel_eqs
+        transfers))
+    |> Thm.close_derivation
+  end;
+
+fun mk_natural_goal ctxt simple_T_mapfs fs t u =
+  let
+    fun build_simple (T, _) =
+      (case AList.lookup (op =) simple_T_mapfs T of
+        SOME mapf => mapf
+      | NONE => the (find_first (fn f => domain_type (fastype_of f) = T) fs));
+
+    val simple_Ts = map fst simple_T_mapfs;
+
+    val t_map = build_map ctxt simple_Ts build_simple (apply2 (range_type o fastype_of) (t, u));
+    val u_map = build_map ctxt simple_Ts build_simple (apply2 (domain_type o fastype_of) (t, u));
+  in
+    mk_Trueprop_eq (HOLogic.mk_comp (u, u_map), HOLogic.mk_comp (t_map, t))
+  end;
+
+fun derive_natural_by_unfolding ctxt live_AsBs preT pre_map fs f const map_thms =
+  let
+    val ffpre_map = list_comb (pre_map, fs) $ f;
+    val constB = subst_atomic_types live_AsBs const;
+
+    val goal = mk_natural_goal ctxt [(preT, ffpre_map)] (fs @ [f]) const constB;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_natural_by_unfolding_tac ctxt map_thms))
+    |> Thm.close_derivation
+  end;
+
+fun derive_natural_from_transfer ctxt live_AsBs simple_T_mapfs fs f const transfer bnfs subst_bnfs =
+  let
+    val m = length live_AsBs;
+
+    val constB = Term.subst_atomic_types live_AsBs const;
+    val goal = mk_natural_goal ctxt simple_T_mapfs (fs @ [f]) const constB;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_natural_from_transfer_tac ctxt m (replicate m true) transfer [] (map rel_Grp_of_bnf bnfs)
+        (map rel_Grp_of_bnf subst_bnfs)))
+    |> Thm.close_derivation
+  end;
+
+fun derive_natural_from_transfer_with_pre_type ctxt live_AsBs Y Z preT ssig_T pre_map ssig_map fs
+    f =
+  let
+    val ssig_TB = typ_subst_atomic live_AsBs ssig_T;
+    val preT' = Term.typ_subst_atomic [(Y, ssig_T), (Z, ssig_TB)] preT;
+
+    val ffpre_map = list_comb (pre_map, fs) $ f;
+    val pre_map' = Term.subst_atomic_types [(Y, ssig_T), (Z, ssig_TB)] pre_map;
+    val fpre_map' = list_comb (pre_map', fs);
+    val ffssig_map = list_comb (ssig_map, fs) $ f;
+
+    val preT_mapfs = [(preT, ffpre_map), (preT', fpre_map' $ ffssig_map)];
+  in
+    derive_natural_from_transfer ctxt live_AsBs preT_mapfs fs f
+  end;
+
+fun derive_Lam_Inl_Inr ctxt Y Z preT old_sig_T old_ssig_T k_T ssig_T dead_pre_map Sig embL old_Lam
+    Lam rho unsig_thm Lam_def =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val Ypre_old_sig_T = Tsubst Y YpreT old_sig_T;
+    val Ypre_k_T = Tsubst Y YpreT k_T;
+
+    val inl' = Inl_const Ypre_old_sig_T Ypre_k_T;
+    val inr' = Inr_const Ypre_old_sig_T Ypre_k_T;
+    val dead_pre_map' = Term.subst_atomic_types [(Y, old_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val Sig' = substT Y YpreT Sig;
+    val Lam_o_Sig = HOLogic.mk_comp (Lam, Sig');
+
+    val inl_goal = mk_Trueprop_eq (HOLogic.mk_comp (Lam_o_Sig, inl'),
+      HOLogic.mk_comp (dead_pre_map' $ embL, old_Lam));
+    val inr_goal = mk_Trueprop_eq (HOLogic.mk_comp (Lam_o_Sig, inr'), rho);
+    val goals = [inl_goal, inr_goal];
+    val goal = Logic.mk_conjunction_balanced goals;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal
+      (fn {context = ctxt, prems = _} => mk_Lam_Inl_Inr_tac ctxt unsig_thm Lam_def))
+    |> Conjunction.elim_balanced (length goals)
+    |> map Thm.close_derivation
+  end;
+
+fun derive_flat_VLeaf ctxt Y Z ssig_T x VLeaf dead_ssig_map flat ssig_induct fp_map_id sig_map_cong
+    sig_map_ident sig_map_comp ssig_map_thms flat_simps =
+  let
+    val x' = substT Y ssig_T x;
+    val dead_ssig_map' = substT Z ssig_T dead_ssig_map;
+
+    val goal = mk_Trueprop_eq (flat $ (dead_ssig_map' $ VLeaf $ x'), x');
+
+    val ssig_induct' = infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt x')] ssig_induct;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_flat_VLeaf_or_flat_tac ctxt ssig_induct' sig_map_cong
+        (fp_map_id :: sig_map_ident :: sig_map_comp :: ssig_map_thms @ flat_simps @
+         @{thms o_apply id_apply id_def[symmetric]})))
+    |> Thm.close_derivation
+  end;
+
+fun derive_flat_flat ctxt Y Z ssig_T x dead_ssig_map flat ssig_induct fp_map_id sig_map_cong
+    sig_map_comp ssig_map_thms flat_simps =
+  let
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T;
+    val ssig_ssig_ssig_T = Tsubst Y ssig_T ssig_ssig_T;
+
+    val x' = substT Y ssig_ssig_ssig_T x;
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_ssig_map;
+    val flat' = substT Y ssig_T flat;
+
+    val goal = mk_Trueprop_eq (flat $ (dead_ssig_map' $ flat $ x'), flat $ (flat' $ x'));
+
+    val ssig_induct' = infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt x')] ssig_induct;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_flat_VLeaf_or_flat_tac ctxt ssig_induct' sig_map_cong
+        (o_apply :: fp_map_id :: sig_map_comp :: ssig_map_thms @ flat_simps)))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_core_flat ctxt Y Z preT ssig_T dead_pre_map dead_ssig_map flat eval_core x
+    ssig_induct dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp fp_map_id sig_map_comp
+    sig_map_cong ssig_map_thms ssig_map_comp flat_simps flat_pointful_natural flat_flat
+    Lam_pointful_natural eval_core_simps =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val ssig_ssig_T = Tsubst Y ssig_T ssig_T;
+    val Ypre_ssig_T = Tsubst Y YpreT ssig_T;
+    val Ypre_ssig_ssig_T = Tsubst Y YpreT ssig_ssig_T;
+    val ssig_YpreT = Tsubst Y ssig_T YpreT;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, ssig_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, Ypre_ssig_T), (Z, ssig_YpreT)] dead_ssig_map;
+    val dead_ssig_map'' = Term.subst_atomic_types [(Y, YpreT), (Z, Y)] dead_ssig_map;
+    val flat' = substT Y YpreT flat;
+    val eval_core' = substT Y ssig_T eval_core;
+    val x' = substT Y Ypre_ssig_ssig_T x;
+    val fst' = fst_const YpreT;
+
+    val goal = mk_Trueprop_eq (eval_core $ (flat' $ x'), dead_pre_map' $ flat
+      $ (eval_core' $ (dead_ssig_map' $ mk_convol (dead_ssig_map'' $ fst', eval_core) $ x')));
+
+    val ssig_induct' = infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt x')] ssig_induct;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_core_flat_tac ctxt ssig_induct' dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp
+        fp_map_id sig_map_comp sig_map_cong ssig_map_thms ssig_map_comp flat_simps
+        flat_pointful_natural flat_flat Lam_pointful_natural eval_core_simps))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_thm ctxt dtor_inject dtor_unfold_thm eval_def =
+  (trans OF [iffD2 OF [dtor_inject, eval_def RS meta_eq_to_obj_eq RS fun_cong], dtor_unfold_thm])
+  |> unfold_thms ctxt [o_apply, eval_def RS Drule.symmetric_thm];
+
+fun derive_eval_flat ctxt Y Z fpT ssig_T dead_ssig_map flat eval x dead_pre_map_comp0
+    dtor_unfold_unique ssig_map_id ssig_map_comp flat_pointful_natural eval_core_pointful_natural
+    eval_core_flat eval_thm =
+  let
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+    val fp_ssig_ssig_T = Tsubst Y fp_ssig_T ssig_T;
+
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_ssig_map;
+    val flat' = substT Y fpT flat;
+    val x' = substT Y fp_ssig_ssig_T x;
+
+    val goal = mk_Trueprop_eq (eval $ (flat' $ x'), eval $ (dead_ssig_map' $ eval $ x'));
+
+    val cond_eval_o_flat =
+      infer_instantiate' ctxt [SOME (Thm.cterm_of ctxt (HOLogic.mk_comp (eval, flat')))]
+        (trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym] RS fun_cong)
+      OF [ext, ext];
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_flat_tac ctxt dead_pre_map_comp0 ssig_map_id ssig_map_comp flat_pointful_natural
+        eval_core_pointful_natural eval_core_flat eval_thm cond_eval_o_flat))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_Oper ctxt live Y Z fpT sig_T ssig_T dead_sig_map Oper eval algLam x sig_map_ident
+    sig_map_comp0 sig_map_comp Oper_natural_pointful VLeaf_natural flat_simps eval_flat algLam_def =
+  let
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+    val fp_ssig_sig_T = Tsubst Y fp_ssig_T sig_T;
+
+    val dead_sig_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_sig_map;
+    val Oper' = substT Y fpT Oper;
+    val x' = substT Y fp_ssig_sig_T x;
+
+    val goal = mk_Trueprop_eq (eval $ (Oper' $ x'), algLam $ (dead_sig_map' $ eval $ x'));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_Oper_tac ctxt live sig_map_ident sig_map_comp0 sig_map_comp Oper_natural_pointful
+        VLeaf_natural flat_simps eval_flat algLam_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_V_or_CLeaf ctxt Y fpT V_or_CLeaf eval x dead_pre_map_id dead_pre_map_comp fp_map_id
+    dtor_unfold_unique V_or_CLeaf_map_thm eval_core_simps eval_thm =
+  let
+    val V_or_CLeaf' = substT Y fpT V_or_CLeaf;
+    val x' = substT Y fpT x;
+
+    val goal = mk_Trueprop_eq (eval $ (V_or_CLeaf' $ x'), x');
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_V_or_CLeaf_tac ctxt dead_pre_map_id dead_pre_map_comp fp_map_id dtor_unfold_unique
+        V_or_CLeaf_map_thm eval_core_simps eval_thm))
+    |> Thm.close_derivation
+  end;
+
+fun derive_extdd_mor ctxt Y Z preT fpT ssig_T dead_pre_map dtor extdd cutSsig f g dead_pre_map_comp0
+    dead_pre_map_comp VLeaf_map_thm ssig_map_comp flat_pointful_natural eval_core_pointful_natural
+    eval_thm eval_flat eval_VLeaf cutSsig_def =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, ssig_T), (Z, fpT)] dead_pre_map;
+    val f' = substT Z fpT f;
+    val g' = substT Z ssig_preT g;
+    val extdd_f = extdd $ f';
+
+    val prem = mk_Trueprop_eq (HOLogic.mk_comp (dead_pre_map' $ extdd_f, g'),
+      HOLogic.mk_comp (dtor, f'));
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (dead_pre_map' $ extdd_f, cutSsig $ g'),
+      HOLogic.mk_comp (dtor, extdd_f));
+  in
+    fold (Variable.add_free_names ctxt) [prem, goal] []
+    |> (fn vars => Goal.prove_sorry ctxt vars [prem] goal (fn {context = ctxt, prems = [prem]} =>
+      mk_extdd_mor_tac ctxt dead_pre_map_comp0 dead_pre_map_comp VLeaf_map_thm ssig_map_comp
+        flat_pointful_natural eval_core_pointful_natural eval_thm eval_flat eval_VLeaf cutSsig_def
+        prem))
+    |> Thm.close_derivation
+  end;
+
+fun derive_mor_cutSsig_flat ctxt Y Z preT fpT ssig_T dead_pre_map dead_ssig_map dtor flat eval_core
+    eval cutSsig f g dead_pre_map_comp0 dead_pre_map_comp dead_pre_map_cong dtor_unfold_unique
+    dead_ssig_map_comp0 ssig_map_comp flat_simps flat_pointful_natural eval_core_pointful_natural
+    flat_flat flat_VLeaf eval_core_flat cutSsig_def cutSsig_def_pointful_natural eval_thm =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+
+    val substYZ = Term.subst_atomic_types [(Y, ssig_T), (Z, fpT)];
+
+    val dead_pre_map' = substYZ dead_pre_map;
+    val dead_ssig_map' = substYZ dead_ssig_map;
+    val f' = substYZ f;
+    val g' = substT Z ssig_preT g;
+    val cutSsig_g = cutSsig $ g';
+
+    val id' = HOLogic.id_const ssig_T;
+    val convol' = mk_convol (id', cutSsig_g);
+    val dead_ssig_map'' =
+      Term.subst_atomic_types [(Y, ssig_T), (Z, range_type (fastype_of convol'))] dead_ssig_map;
+    val eval_core' = substT Y ssig_T eval_core;
+    val eval_core_o_map = HOLogic.mk_comp (eval_core', dead_ssig_map'' $ convol');
+
+    val prem = mk_Trueprop_eq (HOLogic.mk_comp (dead_pre_map' $ f', cutSsig_g),
+      HOLogic.mk_comp (dtor, f'));
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (eval, dead_ssig_map' $ f'),
+      HOLogic.mk_comp (f', flat));
+  in
+    fold (Variable.add_free_names ctxt) [prem, goal] []
+    |> (fn vars => Goal.prove_sorry ctxt vars [prem] goal (fn {context = ctxt, prems = [prem]} =>
+      mk_mor_cutSsig_flat_tac ctxt eval_core_o_map dead_pre_map_comp0 dead_pre_map_comp
+        dead_pre_map_cong dtor_unfold_unique dead_ssig_map_comp0 ssig_map_comp flat_simps
+        flat_pointful_natural eval_core_pointful_natural flat_flat flat_VLeaf eval_core_flat
+        cutSsig_def cutSsig_def_pointful_natural eval_thm prem))
+    |> Thm.close_derivation
+  end;
+
+fun derive_extdd_o_VLeaf ctxt Y Z preT fpT ssig_T dead_pre_map dtor VLeaf extdd f g
+    dead_pre_map_comp0 dead_pre_map_comp dtor_inject ssig_map_thms eval_core_simps eval_thm
+    eval_VLeaf =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+
+    val substYZ = Term.subst_atomic_types [(Y, ssig_T), (Z, fpT)];
+
+    val dead_pre_map' = substYZ dead_pre_map;
+    val f' = substT Z fpT f;
+    val g' = substT Z ssig_preT g;
+    val extdd_f = extdd $ f';
+
+    val prem = mk_Trueprop_eq (HOLogic.mk_comp (dead_pre_map' $ extdd_f, g'),
+      HOLogic.mk_comp (dtor, f'));
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (extdd_f, VLeaf), f');
+  in
+    fold (Variable.add_free_names ctxt) [prem, goal] []
+    |> (fn vars => Goal.prove_sorry ctxt vars [prem] goal (fn {context = ctxt, prems = [prem]} =>
+      mk_extdd_o_VLeaf_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_inject ssig_map_thms
+        eval_core_simps eval_thm eval_VLeaf prem))
+    |> Thm.close_derivation
+  end;
+
+fun derive_corecU_pointfree ctxt Y Z preT fpT ssig_T dead_pre_map dtor extdd corecU g
+    dead_pre_map_comp dtor_unfold_thm ssig_map_thms dead_ssig_map_comp0 flat_simps flat_VLeaf
+    eval_core_simps cutSsig_def mor_cutSsig_flat corecU_def =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+
+    val substYZ = Term.subst_atomic_types [(Y, ssig_T), (Z, fpT)];
+
+    val dead_pre_map' = substYZ dead_pre_map;
+    val g' = substT Z ssig_preT g;
+    val corecU_g = corecU $ g';
+
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (dead_pre_map' $ (extdd $ corecU_g), g'),
+      HOLogic.mk_comp (dtor, corecU_g));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_corecU_pointfree_tac ctxt dead_pre_map_comp dtor_unfold_thm ssig_map_thms
+      dead_ssig_map_comp0 flat_simps flat_VLeaf eval_core_simps cutSsig_def mor_cutSsig_flat
+      corecU_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_corecU_ctor_unique ctxt Y Z preT fpT ssig_T dead_pre_map ctor dtor VLeaf extdd corecU f g
+    dead_pre_map_comp ctor_dtor dtor_unfold_thm dtor_unfold_unique ssig_map_thms dead_ssig_map_comp0
+    flat_simps flat_VLeaf eval_core_simps extdd_mor extdd_o_VLeaf cutSsig_def mor_cutSsig_flat
+    corecU_def =
+  let
+    val corecU_pointfree = derive_corecU_pointfree ctxt Y Z preT fpT ssig_T dead_pre_map dtor extdd
+      corecU g dead_pre_map_comp dtor_unfold_thm ssig_map_thms dead_ssig_map_comp0 flat_simps
+      flat_VLeaf eval_core_simps cutSsig_def mor_cutSsig_flat corecU_def;
+
+    val corecU_thm = corecU_pointfree RS @{thm comp_eq_dest};
+
+    val corecU_ctor =
+      let
+        val arg_cong' =
+          infer_instantiate' ctxt [NONE, NONE, SOME (Thm.cterm_of ctxt ctor)] arg_cong;
+      in
+        unfold_thms ctxt [ctor_dtor] (corecU_thm RS arg_cong')
+      end;
+
+    val corecU_unique =
+      let
+        val substYZ = Term.subst_atomic_types [(Y, ssig_T), (Z, fpT)];
+
+        val f' = substYZ f;
+        val abs_f_o_VLeaf = Term.lambda f' (HOLogic.mk_comp (f', VLeaf));
+
+        val inject_refine' = infer_instantiate' ctxt [SOME (Thm.cterm_of ctxt abs_f_o_VLeaf),
+          SOME (Thm.cterm_of ctxt extdd)] @{thm inject_refine};
+      in
+        unfold_thms ctxt @{thms atomize_imp}
+          (((inject_refine' OF [extdd_o_VLeaf, extdd_o_VLeaf] RS iffD1)
+            OF [Drule.asm_rl, corecU_pointfree])
+           OF [Drule.asm_rl, trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym]
+             OF [extdd_mor, corecU_pointfree RS extdd_mor]])
+        RS @{thm obj_distinct_prems}
+      end;
+  in
+    (corecU_ctor, corecU_unique)
+  end;
+
+fun derive_dtor_algLam ctxt Y Z preT fpT sig_T ssig_T dead_pre_map dtor dead_sig_map Lam eval algLam
+    x pre_map_comp dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp sig_map_comp
+    Oper_pointful_natural ssig_map_thms dead_ssig_map_comp0 Lam_pointful_natural eval_core_simps
+    eval_thm eval_flat eval_VLeaf algLam_def =
+  let
+    val fp_preT = Tsubst Y fpT preT;
+    val fppreT = HOLogic.mk_prodT (fpT, fp_preT);
+    val fp_sig_T = Tsubst Y fpT sig_T;
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val id' = HOLogic.id_const fpT;
+    val convol' = mk_convol (id', dtor);
+    val dead_pre_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_pre_map;
+    val dead_sig_map' = Term.subst_atomic_types [(Y, fpT), (Z, fppreT)] dead_sig_map;
+    val Lam' = substT Y fpT Lam;
+    val x' = substT Y fp_sig_T x;
+
+    val goal = mk_Trueprop_eq (dtor $ (algLam $ x'),
+      dead_pre_map' $ eval $ (Lam' $ (dead_sig_map' $ convol' $ x')));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_dtor_algLam_tac ctxt pre_map_comp dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp
+        sig_map_comp Oper_pointful_natural ssig_map_thms dead_ssig_map_comp0 Lam_pointful_natural
+        eval_core_simps eval_thm eval_flat eval_VLeaf algLam_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_algLam_base ctxt Y Z preT fpT dead_pre_map ctor dtor algLam proto_sctr dead_pre_map_id
+    dead_pre_map_comp ctor_dtor dtor_ctor dtor_unfold_unique unsig_thm Sig_pointful_natural
+    ssig_map_thms Lam_def flat_simps eval_core_simps eval_thm algLam_def =
+  let
+    val fp_preT = Tsubst Y fpT preT;
+
+    val proto_sctr' = substT Y fpT proto_sctr;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, fpT), (Z, fp_preT)] dead_pre_map;
+    val dead_pre_map_dtor = dead_pre_map' $ dtor;
+
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (algLam, proto_sctr'), ctor);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_algLam_base_tac ctxt dead_pre_map_dtor dead_pre_map_id dead_pre_map_comp ctor_dtor
+        dtor_ctor dtor_unfold_unique unsig_thm Sig_pointful_natural ssig_map_thms Lam_def flat_simps
+        eval_core_simps eval_thm algLam_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_flat_embL ctxt Y Z old_ssig_T ssig_T dead_old_ssig_map embL old_flat flat x
+    old_ssig_induct fp_map_id Sig_pointful_natural old_sig_map_comp old_sig_map_cong
+    old_ssig_map_thms old_flat_simps flat_simps embL_simps =
+  let
+    val old_ssig_old_ssig_T = Tsubst Y old_ssig_T old_ssig_T;
+
+    val dead_old_ssig_map' =
+      Term.subst_atomic_types [(Y, old_ssig_T), (Z, ssig_T)] dead_old_ssig_map;
+    val embL' = substT Y ssig_T embL;
+    val x' = substT Y old_ssig_old_ssig_T x;
+
+    val goal = mk_Trueprop_eq (flat $ (embL' $ (dead_old_ssig_map' $ embL $ x')),
+      embL $ (old_flat $ x'));
+
+    val old_ssig_induct' =
+      infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt x')] old_ssig_induct;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_flat_embL_tac ctxt old_ssig_induct' fp_map_id Sig_pointful_natural old_sig_map_comp
+        old_sig_map_cong old_ssig_map_thms old_flat_simps flat_simps embL_simps))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_core_embL ctxt Y Z preT old_ssig_T ssig_T dead_pre_map embL old_eval_core eval_core
+    x old_ssig_induct dead_pre_map_comp0 dead_pre_map_comp Sig_pointful_natural unsig_thm
+    old_sig_map_comp old_sig_map_cong old_Lam_pointful_natural Lam_def flat_embL embL_simps
+    embL_pointful_natural old_eval_core_simps eval_core_simps =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val Ypre_old_ssig_T = Tsubst Y YpreT old_ssig_T;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, old_ssig_T), (Z, ssig_T)] dead_pre_map;
+    val embL' = substT Y YpreT embL;
+    val x' = substT Y Ypre_old_ssig_T x;
+
+    val goal =
+      mk_Trueprop_eq (eval_core $ (embL' $ x'), dead_pre_map' $ embL $ (old_eval_core $ x'));
+
+    val old_ssig_induct' =
+      infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt x')] old_ssig_induct;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_core_embL_tac ctxt old_ssig_induct' dead_pre_map_comp0 dead_pre_map_comp
+        Sig_pointful_natural unsig_thm old_sig_map_comp old_sig_map_cong old_Lam_pointful_natural
+        Lam_def flat_embL old_eval_core_simps eval_core_simps embL_simps embL_pointful_natural))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_embL ctxt Y fpT embL old_eval eval dead_pre_map_comp0 dtor_unfold_unique
+    embL_pointful_natural eval_core_embL old_eval_thm eval_thm =
+  let
+    val embL' = substT Y fpT embL;
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (eval, embL'), old_eval);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_embL_tac ctxt dead_pre_map_comp0 dtor_unfold_unique embL_pointful_natural
+        eval_core_embL old_eval_thm eval_thm))
+    |> Thm.close_derivation
+  end;
+
+fun derive_algLam_algLam ctxt Inx_const Y fpT Sig old_algLam algLam dead_pre_map_comp dtor_inject
+    unsig_thm sig_map_thm Lam_def eval_embL old_dtor_algLam dtor_algLam =
+  let
+    val Sig' = substT Y fpT Sig;
+    val (left_T, right_T) = dest_sumT (domain_type (fastype_of Sig'));
+    val inx' = Inx_const left_T right_T;
+
+    val goal = mk_Trueprop_eq (Library.foldl1 HOLogic.mk_comp [algLam, Sig', inx'], old_algLam);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_algLam_algLam_tac ctxt dead_pre_map_comp dtor_inject unsig_thm sig_map_thm Lam_def
+        eval_embL old_dtor_algLam dtor_algLam))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_core_k_as_ssig ctxt Y preT k_T rho eval_core k_as_ssig x pre_map_comp
+    dead_pre_map_id sig_map_comp ssig_map_thms Lam_natural_pointful Lam_Inr flat_VLeaf
+    eval_core_simps =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val Ypre_k_T = Tsubst Y YpreT k_T;
+
+    val k_as_ssig' = substT Y YpreT k_as_ssig;
+    val x' = substT Y Ypre_k_T x;
+
+    val goal = mk_Trueprop_eq (eval_core $ (k_as_ssig' $ x'), rho $ x');
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_core_k_as_ssig_tac ctxt pre_map_comp dead_pre_map_id sig_map_comp ssig_map_thms
+        Lam_natural_pointful Lam_Inr flat_VLeaf eval_core_simps))
+    |> Thm.close_derivation
+  end;
+
+fun derive_algLam_algrho ctxt Y fpT Sig algLam algrho algLam_def algrho_def =
+  let
+    val Sig' = substT Y fpT Sig;
+    val (left_T, right_T) = dest_sumT (domain_type (fastype_of Sig'));
+    val inr' = Inr_const left_T right_T;
+
+    val goal = mk_Trueprop_eq (Library.foldl1 HOLogic.mk_comp [algLam, Sig', inr'], algrho);
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_algLam_algrho_tac ctxt algLam_def algrho_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_dtor_algrho ctxt Y Z preT fpT k_T ssig_T dead_pre_map dead_k_map dtor rho eval algrho x
+    eval_thm k_as_ssig_natural_pointful eval_core_k_as_ssig algrho_def =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val fppreT = Tsubst Y fpT YpreT;
+    val fp_k_T = Tsubst Y fpT k_T;
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val id' = HOLogic.id_const fpT;
+    val convol' = mk_convol (id', dtor);
+    val dead_pre_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_pre_map;
+    val dead_k_map' = Term.subst_atomic_types [(Y, fpT), (Z, fppreT)] dead_k_map;
+    val rho' = substT Y fpT rho;
+    val x' = substT Y fp_k_T x;
+
+    val goal = mk_Trueprop_eq (dtor $ (algrho $ x'),
+      dead_pre_map' $ eval $ (rho' $ (dead_k_map' $ convol' $ x')));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_dtor_algrho_tac ctxt eval_thm k_as_ssig_natural_pointful eval_core_k_as_ssig algrho_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_algLam_step_or_merge ctxt Y fpT ctor proto_sctr algLam proto_sctr_def old_algLam_pointful
+    algLam_algLam =
+  let
+    val proto_sctr' = substT Y fpT proto_sctr;
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (algLam, proto_sctr'), ctor);
+
+    val algLam_algLam_pointful = mk_pointful ctxt algLam_algLam;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_algLam_step_tac ctxt proto_sctr_def old_algLam_pointful algLam_algLam_pointful))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eval_sctr ctxt Y Z fpT ssig_T dead_pre_map ctor eval sctr proto_sctr_pointful_natural
+    eval_Oper algLam_thm sctr_def =
+  let
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_pre_map;
+    val sctr' = substT Y fpT sctr;
+
+    val goal = mk_Trueprop_eq (HOLogic.mk_comp (eval, sctr'),
+      HOLogic.mk_comp (ctor, dead_pre_map' $ eval));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_eval_sctr_tac ctxt proto_sctr_pointful_natural eval_Oper algLam_thm sctr_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_corecUU_pointfree_unique ctxt Y Z preT fpT ssig_T dead_pre_map ctor dead_ssig_map eval
+    corecUU f g dead_pre_map_comp0 dead_pre_map_comp dtor_ctor dtor_inject ssig_map_comp
+    flat_pointful_natural eval_core_pointful_natural eval_thm eval_flat corecU_ctor corecU_unique
+    sctr_pointful_natural eval_sctr_pointful corecUU_def =
+  let
+    val ssig_preT = Tsubst Y ssig_T preT;
+    val ssig_pre_ssig_T = Tsubst Y ssig_preT ssig_T;
+    val fp_ssig_T = Tsubst Y fpT ssig_T;
+
+    val dead_pre_map' = Term.subst_atomic_types [(Y, fp_ssig_T), (Z, fpT)] dead_pre_map;
+    val dead_pre_map'' = Term.subst_atomic_types [(Y, ssig_T), (Z, fp_ssig_T)] dead_pre_map;
+    val dead_ssig_map' = Term.subst_atomic_types [(Y, ssig_preT), (Z, fpT)] dead_ssig_map;
+    val dead_ssig_map'' = substT Z fpT dead_ssig_map;
+    val f' = substT Z ssig_pre_ssig_T f;
+    val g' = substT Z fpT g;
+    val corecUU_f = corecUU $ f';
+
+    fun mk_eq fpf =
+      mk_Trueprop_eq (fpf, Library.foldl1 HOLogic.mk_comp [eval, dead_ssig_map' $
+          Library.foldl1 HOLogic.mk_comp [ctor, dead_pre_map' $ eval, dead_pre_map''
+            $ (dead_ssig_map'' $ fpf)],
+        f']);
+
+    val corecUU_pointfree =
+      let
+        val goal = mk_eq corecUU_f;
+      in
+        Variable.add_free_names ctxt goal []
+        |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+          mk_corecUU_pointfree_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor dtor_inject
+            ssig_map_comp flat_pointful_natural eval_core_pointful_natural eval_thm eval_flat
+            corecU_ctor sctr_pointful_natural eval_sctr_pointful corecUU_def))
+        |> Thm.close_derivation
+      end;
+
+    val corecUU_unique =
+      let
+        val prem = mk_eq g';
+        val goal = mk_Trueprop_eq (g', corecUU_f);
+      in
+        fold (Variable.add_free_names ctxt) [prem, goal] []
+        |> (fn vars => Goal.prove_sorry ctxt vars [prem] goal
+              (fn {context = ctxt, prems = [prem]} =>
+                mk_corecUU_unique_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor
+                  ssig_map_comp flat_pointful_natural eval_core_pointful_natural eval_thm eval_flat
+                  corecU_unique sctr_pointful_natural eval_sctr_pointful corecUU_def prem))
+        |> Thm.close_derivation
+      end;
+  in
+    (corecUU_pointfree, corecUU_unique)
+  end;
+
+fun define_flat_etc fp_b version live_AsBs Y Z preT fpT sig_T ssig_T Oper VLeaf CLeaf pre_rel
+    dead_pre_map dtor dtor_unfold dead_sig_map ssig_rel dead_ssig_map Lam Rs R pre_map_transfer
+    fp_k_T_rel_eqs sig_map_transfer ssig_map_transfer Lam_transfer dtor_transfer lthy =
+  let
+    val (flat_data as (flat, flat_def, _), lthy) = lthy
+      |> define_flat fp_b version Y Z fpT sig_T ssig_T Oper VLeaf CLeaf dead_sig_map;
+
+    val (eval_core_data as (eval_core, eval_core_def, _), lthy) = lthy
+      |> define_eval_core fp_b version Y Z preT fpT sig_T ssig_T dtor Oper VLeaf CLeaf dead_pre_map
+        dead_sig_map dead_ssig_map flat Lam;
+
+    val ((eval_data as (eval, _), cutSsig_data as (cutSsig, _)), lthy) = lthy
+      |> define_eval fp_b version Y Z preT fpT ssig_T dtor dtor_unfold dead_ssig_map eval_core
+      ||>> define_cutSsig fp_b version Y Z preT ssig_T dead_pre_map VLeaf dead_ssig_map flat
+        eval_core;
+
+    val ((algLam_data, unfold_data), lthy) = lthy
+      |> define_algLam fp_b version Y Z fpT ssig_T Oper VLeaf dead_sig_map eval
+      ||>> define_corecU fp_b version Y Z preT ssig_T dtor_unfold VLeaf cutSsig;
+
+    val flat_transfer = derive_transfer_by_transfer_prover lthy live_AsBs Rs R flat [flat_def] []
+      [sig_map_transfer];
+    val eval_core_transfer = derive_Lam_or_eval_core_transfer lthy live_AsBs Y Z preT ssig_T Rs R
+      pre_rel ssig_rel ssig_rel eval_core eval_core_def fp_k_T_rel_eqs
+      [pre_map_transfer, sig_map_transfer, ssig_map_transfer, flat_transfer, Lam_transfer,
+       dtor_transfer];
+  in
+    (((((((flat_data, flat_transfer), (eval_core_data, eval_core_transfer)), eval_data),
+      cutSsig_data), algLam_data), unfold_data), lthy)
+  end;
+
+fun derive_Sig_natural_etc ctxt live live_AsBs Y Z preT fpT k_or_fpT sig_T ssig_T pre_map
+    dead_pre_map ctor dtor Sig dead_sig_map Oper VLeaf CLeaf ssig_map dead_ssig_map Lam flat
+    eval_core eval cutSsig algLam corecU x fs f g ctor_dtor dtor_inject dtor_unfold_thm
+    dtor_unfold_unique sig_map_thm ssig_induct ssig_map_thms Oper_map_thm VLeaf_map_thm
+    CLeaf_map_thm Lam_transfer flat_simps flat_transfer eval_core_simps eval_core_transfer eval_def
+    cutSsig_def algLam_def corecU_def live_pre_bnf pre_bnf dead_pre_bnf fp_bnf sig_bnf ssig_bnf
+    dead_ssig_bnf =
+  let
+    val SOME prod_fp_sugar = fp_sugar_of ctxt @{type_name prod};
+    val prod_bnf = #fp_bnf prod_fp_sugar;
+
+    val f' = substT Z fpT f;
+    val dead_ssig_map' = substT Z fpT dead_ssig_map;
+    val extdd = Term.lambda f' (HOLogic.mk_comp (eval, dead_ssig_map' $ f'));
+
+    val live_pre_map_def = map_def_of_bnf live_pre_bnf;
+    val pre_map_comp = map_comp_of_bnf pre_bnf;
+    val dead_pre_map_id = map_id_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp0 = map_comp0_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp = map_comp_of_bnf dead_pre_bnf;
+    val dead_pre_map_cong = map_cong_of_bnf dead_pre_bnf;
+    val fp_map_id = map_id_of_bnf fp_bnf;
+    val sig_map_ident = map_ident_of_bnf sig_bnf;
+    val sig_map_comp0 = map_comp0_of_bnf sig_bnf;
+    val sig_map_comp = map_comp_of_bnf sig_bnf;
+    val sig_map_cong = map_cong_of_bnf sig_bnf;
+    val ssig_map_id = map_id_of_bnf ssig_bnf;
+    val ssig_map_comp = map_comp_of_bnf ssig_bnf;
+    val dead_ssig_map_comp0 = map_comp0_of_bnf dead_ssig_bnf;
+
+    val k_preT_map_id0s =
+      map map_id0_of_bnf (map_filter (bnf_of ctxt) (fold add_type_namesT [preT, k_or_fpT] []));
+
+    val Sig_natural = derive_natural_by_unfolding ctxt live_AsBs preT pre_map fs f Sig
+      ([sig_map_thm, live_pre_map_def, @{thm BNF_Composition.id_bnf_def}] @ k_preT_map_id0s);
+    val Oper_natural =
+      derive_natural_by_unfolding ctxt live_AsBs preT pre_map fs f Oper [Oper_map_thm];
+    val VLeaf_natural =
+      derive_natural_by_unfolding ctxt live_AsBs preT pre_map fs f VLeaf [VLeaf_map_thm];
+    val Lam_natural = derive_natural_from_transfer_with_pre_type ctxt live_AsBs Y Z preT ssig_T
+      pre_map ssig_map fs f Lam Lam_transfer [prod_bnf, pre_bnf, sig_bnf, ssig_bnf] [];
+    val flat_natural = derive_natural_from_transfer ctxt live_AsBs [] fs f flat flat_transfer
+      [ssig_bnf] [];
+    val eval_core_natural = derive_natural_from_transfer_with_pre_type ctxt live_AsBs Y Z preT
+      ssig_T pre_map ssig_map fs f eval_core eval_core_transfer [prod_bnf, pre_bnf, ssig_bnf] [];
+
+    val Sig_pointful_natural = mk_pointful ctxt Sig_natural RS sym;
+    val Oper_natural_pointful = mk_pointful ctxt Oper_natural;
+    val Oper_pointful_natural = Oper_natural_pointful RS sym;
+    val flat_pointful_natural = mk_pointful ctxt flat_natural RS sym;
+    val Lam_natural_pointful = mk_pointful ctxt Lam_natural;
+    val Lam_pointful_natural = Lam_natural_pointful RS sym;
+    val eval_core_pointful_natural = mk_pointful ctxt eval_core_natural RS sym;
+    val cutSsig_def_pointful_natural = mk_pointful ctxt (cutSsig_def RS meta_eq_to_obj_eq) RS sym;
+
+    val flat_VLeaf = derive_flat_VLeaf ctxt Y Z ssig_T x VLeaf dead_ssig_map flat ssig_induct
+      fp_map_id sig_map_cong sig_map_ident sig_map_comp ssig_map_thms flat_simps;
+    val flat_flat = derive_flat_flat ctxt Y Z ssig_T x dead_ssig_map flat ssig_induct fp_map_id
+      sig_map_cong sig_map_comp ssig_map_thms flat_simps;
+
+    val eval_core_flat = derive_eval_core_flat ctxt Y Z preT ssig_T dead_pre_map dead_ssig_map flat
+      eval_core x ssig_induct dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp fp_map_id
+      sig_map_comp sig_map_cong ssig_map_thms ssig_map_comp flat_simps flat_pointful_natural
+      flat_flat Lam_pointful_natural eval_core_simps;
+
+    val eval_thm = derive_eval_thm ctxt dtor_inject dtor_unfold_thm eval_def;
+    val eval_flat = derive_eval_flat ctxt Y Z fpT ssig_T dead_ssig_map flat eval x
+      dead_pre_map_comp0 dtor_unfold_unique ssig_map_id ssig_map_comp flat_pointful_natural
+      eval_core_pointful_natural eval_core_flat eval_thm;
+    val eval_Oper = derive_eval_Oper ctxt live Y Z fpT sig_T ssig_T dead_sig_map Oper eval algLam x
+      sig_map_ident sig_map_comp0 sig_map_comp Oper_natural_pointful VLeaf_natural flat_simps
+      eval_flat algLam_def;
+    val eval_VLeaf = derive_eval_V_or_CLeaf ctxt Y fpT VLeaf eval x dead_pre_map_id
+      dead_pre_map_comp fp_map_id dtor_unfold_unique VLeaf_map_thm eval_core_simps eval_thm;
+    val eval_CLeaf = derive_eval_V_or_CLeaf ctxt Y fpT CLeaf eval x dead_pre_map_id
+      dead_pre_map_comp fp_map_id dtor_unfold_unique CLeaf_map_thm eval_core_simps eval_thm;
+
+    val extdd_mor = derive_extdd_mor ctxt Y Z preT fpT ssig_T dead_pre_map dtor extdd cutSsig f g
+      dead_pre_map_comp0 dead_pre_map_comp VLeaf_map_thm ssig_map_comp flat_pointful_natural
+      eval_core_pointful_natural eval_thm eval_flat eval_VLeaf cutSsig_def;
+    val mor_cutSsig_flat = derive_mor_cutSsig_flat ctxt Y Z preT fpT ssig_T dead_pre_map
+      dead_ssig_map dtor flat eval_core eval cutSsig f g dead_pre_map_comp0 dead_pre_map_comp
+      dead_pre_map_cong dtor_unfold_unique dead_ssig_map_comp0 ssig_map_comp flat_simps
+      flat_pointful_natural eval_core_pointful_natural flat_flat flat_VLeaf eval_core_flat
+      cutSsig_def cutSsig_def_pointful_natural eval_thm;
+    val extdd_o_VLeaf = derive_extdd_o_VLeaf ctxt Y Z preT fpT ssig_T dead_pre_map dtor VLeaf extdd
+      f g dead_pre_map_comp0 dead_pre_map_comp dtor_inject ssig_map_thms eval_core_simps eval_thm
+      eval_VLeaf;
+
+    val (corecU_ctor, corecU_unique) = derive_corecU_ctor_unique ctxt Y Z preT fpT ssig_T
+      dead_pre_map ctor dtor VLeaf extdd corecU f g dead_pre_map_comp ctor_dtor dtor_unfold_thm
+      dtor_unfold_unique ssig_map_thms dead_ssig_map_comp0 flat_simps flat_VLeaf eval_core_simps
+      extdd_mor extdd_o_VLeaf cutSsig_def mor_cutSsig_flat corecU_def;
+
+    val dtor_algLam = derive_dtor_algLam ctxt Y Z preT fpT sig_T ssig_T dead_pre_map dtor
+      dead_sig_map Lam eval algLam x pre_map_comp dead_pre_map_id dead_pre_map_comp0
+      dead_pre_map_comp sig_map_comp Oper_pointful_natural ssig_map_thms dead_ssig_map_comp0
+      Lam_pointful_natural eval_core_simps eval_thm eval_flat eval_VLeaf algLam_def;
+  in
+    (Sig_pointful_natural, flat_pointful_natural, Lam_natural_pointful, Lam_pointful_natural,
+     flat_VLeaf, eval_core_pointful_natural, eval_thm, eval_flat,
+     [eval_Oper, eval_VLeaf, eval_CLeaf], corecU_ctor, corecU_unique, dtor_algLam)
+  end;
+
+fun derive_embL_natural_etc ctxt Inx_const old_ssig_bnf ssig_bnf Y Z preT fpT old_ssig_T ssig_T
+    dead_pre_map Sig dead_old_ssig_map embL old_algLam algLam old_flat flat old_eval_core eval_core
+    old_eval eval x f old_ssig_induct dead_pre_map_comp0 dead_pre_map_comp fp_map_id dtor_inject
+    dtor_unfold_unique Sig_pointful_natural unsig_thm sig_map_thm old_sig_map_comp old_sig_map_cong
+    old_ssig_map_thms old_Lam_pointful_natural Lam_def old_flat_simps flat_simps embL_simps
+    embL_transfer old_eval_core_simps eval_core_simps old_eval_thm eval_thm old_dtor_algLam
+    dtor_algLam old_algLam_thm =
+  let
+    val embL_natural = derive_natural_from_transfer ctxt [(Y, Z)] [] [] f embL embL_transfer
+      [old_ssig_bnf, ssig_bnf] [];
+
+    val embL_pointful_natural = mk_pointful ctxt embL_natural RS sym;
+    val old_algLam_pointful = mk_pointful ctxt old_algLam_thm;
+
+    val flat_embL = derive_flat_embL ctxt Y Z old_ssig_T ssig_T dead_old_ssig_map embL old_flat flat
+      x old_ssig_induct fp_map_id Sig_pointful_natural old_sig_map_comp old_sig_map_cong
+      old_ssig_map_thms old_flat_simps flat_simps embL_simps;
+    val eval_core_embL = derive_eval_core_embL ctxt Y Z preT old_ssig_T ssig_T dead_pre_map embL
+      old_eval_core eval_core x old_ssig_induct dead_pre_map_comp0 dead_pre_map_comp
+      Sig_pointful_natural unsig_thm old_sig_map_comp old_sig_map_cong old_Lam_pointful_natural
+      Lam_def flat_embL embL_simps embL_pointful_natural old_eval_core_simps eval_core_simps;
+    val eval_embL = derive_eval_embL ctxt Y fpT embL old_eval eval dead_pre_map_comp0
+      dtor_unfold_unique embL_pointful_natural eval_core_embL old_eval_thm eval_thm;
+
+    val algLam_algLam = derive_algLam_algLam ctxt Inx_const Y fpT Sig old_algLam algLam
+      dead_pre_map_comp dtor_inject unsig_thm sig_map_thm Lam_def eval_embL old_dtor_algLam
+      dtor_algLam;
+  in
+    (embL_pointful_natural, old_algLam_pointful, eval_embL, algLam_algLam)
+  end;
+
+fun define_corecUU_etc fp_b version live_AsBs Y Z preT fpT ssig_T pre_map dead_pre_map pre_rel
+    fp_rel ctor Oper ssig_map dead_ssig_map ssig_rel proto_sctr flat eval_core eval corecU fs f g Rs
+    R pre_map_transfer fp_k_T_rel_eqs dtor_unfold_transfer dtor_transfer ssig_map_transfer
+    proto_sctr_transfer proto_sctr_pointful_natural flat_transfer flat_pointful_natural
+    eval_core_transfer eval_core_pointful_natural eval_thm eval_flat eval_Oper algLam_thm
+    cutSsig_def corecU_def corecU_ctor corecU_unique pre_bnf dead_pre_bnf fp_res ssig_fp_sugar
+    lthy =
+  let
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+
+    val dead_pre_map_comp0 = map_comp0_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp = map_comp_of_bnf dead_pre_bnf;
+    val [dtor_ctor] = #dtor_ctors fp_res;
+    val [dtor_inject] = #dtor_injects fp_res;
+    val ssig_map_comp = map_comp_of_bnf ssig_bnf;
+
+    val sctr_rhs = HOLogic.mk_comp (Oper, substT Y ssig_T proto_sctr);
+    val ((sctr, sctr_def), lthy) = lthy
+      |> define_const true fp_b version sctrN sctr_rhs;
+
+    val (corecUU_data as (corecUU, corecUU_def), lthy) = lthy
+      |> define_corecUU fp_b version Y Z preT ssig_T dead_pre_map dead_ssig_map flat eval_core sctr
+        corecU;
+
+    val eval_sctr = derive_eval_sctr lthy Y Z fpT ssig_T dead_pre_map ctor eval sctr
+      proto_sctr_pointful_natural eval_Oper algLam_thm sctr_def;
+
+    val sctr_transfer = derive_sctr_transfer lthy live_AsBs Y Z ssig_T Rs R pre_rel ssig_rel sctr
+      sctr_def fp_k_T_rel_eqs [proto_sctr_transfer];
+
+    val sctr_natural = derive_natural_from_transfer_with_pre_type lthy live_AsBs Y Z preT ssig_T
+      pre_map ssig_map fs f sctr sctr_transfer [pre_bnf, ssig_bnf] [];
+
+    val sctr_pointful_natural = mk_pointful lthy sctr_natural RS sym;
+    val eval_sctr_pointful = mk_pointful lthy eval_sctr RS sym;
+
+    val (corecUU_pointfree, corecUU_unique) = derive_corecUU_pointfree_unique lthy Y Z preT fpT
+      ssig_T dead_pre_map ctor dead_ssig_map eval corecUU f g dead_pre_map_comp0 dead_pre_map_comp
+      dtor_ctor dtor_inject ssig_map_comp flat_pointful_natural eval_core_pointful_natural eval_thm
+      eval_flat corecU_ctor corecU_unique sctr_pointful_natural eval_sctr_pointful corecUU_def;
+
+    val corecUU_thm = mk_pointful lthy corecUU_pointfree;
+
+    val corecUU_transfer = derive_corecUU_transfer lthy live_AsBs Y Z Rs R preT ssig_T pre_rel
+      fp_rel ssig_rel corecUU cutSsig_def corecU_def corecUU_def fp_k_T_rel_eqs
+      [pre_map_transfer, dtor_unfold_transfer, dtor_transfer, ssig_map_transfer, flat_transfer,
+       eval_core_transfer, sctr_transfer, @{thm convol_transfer} (*FIXME: needed?*)];
+  in
+    ((corecUU_data, corecUU_thm, corecUU_unique, corecUU_transfer, eval_sctr, sctr_transfer,
+      sctr_pointful_natural), lthy)
+  end;
+
+fun mk_equivp T = Const (@{const_name equivp}, mk_predT [mk_pred2T T T]);
+
+fun derive_equivp_Retr ctxt fpT Retr R dead_pre_rel_refl_thm dead_pre_rel_flip_thm
+    dead_pre_rel_mono_thm dead_pre_rel_compp_thm =
+  let
+    val prem = HOLogic.mk_Trueprop (mk_equivp fpT $ R);
+    val goal = Logic.mk_implies (prem, HOLogic.mk_Trueprop (mk_equivp fpT $ (betapply (Retr, R))));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_equivp_Retr_tac ctxt dead_pre_rel_refl_thm dead_pre_rel_flip_thm dead_pre_rel_mono_thm
+        dead_pre_rel_compp_thm))
+    |> Thm.close_derivation
+  end;
+
+fun derive_Retr_coinduct ctxt fpT Retr R dtor_rel_coinduct_thm rel_eq_thm =
+  let
+    val goal = HOLogic.mk_Trueprop (list_all_free [R]
+      (HOLogic.mk_imp (mk_leq R (Retr $ R), mk_leq R (HOLogic.eq_const fpT))));
+  in
+    Goal.prove_sorry ctxt [] [] goal (fn {context = ctxt, prems = _} =>
+      mk_Retr_coinduct_tac ctxt dtor_rel_coinduct_thm rel_eq_thm)
+    |> Thm.close_derivation
+  end;
+
+fun derive_Retr fp_sugar fpT dead_pre_bnf ctor dtor names_lthy lthy =
+  let
+    val (R, _) = names_lthy
+      |> yield_singleton (mk_Frees "R") (mk_pred2T fpT fpT);
+    val pre_fpT = pre_type_of_ctor fpT ctor;
+    val fp_pre_rel = mk_rel1 lthy fpT fpT pre_fpT dead_pre_bnf;
+    val Retr = Abs ("R", fastype_of R, Abs ("a", fpT,
+      Abs ("b", fpT, list_comb (fp_pre_rel, [Bound 2, dtor $ Bound 1, dtor $ Bound 0]))));
+    val equivp_Retr = derive_equivp_Retr lthy fpT Retr R (rel_refl_of_bnf dead_pre_bnf)
+      (rel_flip_of_bnf dead_pre_bnf) (rel_mono_of_bnf dead_pre_bnf) (rel_OO_of_bnf dead_pre_bnf);
+
+    val Retr_coinduct = derive_Retr_coinduct lthy fpT Retr R
+      (fp_sugar |> #fp_res |> #xtor_rel_co_induct) (fp_sugar |> #fp_bnf |> rel_eq_of_bnf);
+  in
+    (Retr, equivp_Retr, Retr_coinduct)
+  end;
+
+fun mk_gen_cong fpT eval_domT =
+  let val fp_relT = mk_pred2T fpT fpT in
+    Const (@{const_name "cong.gen_cong"},
+      [mk_predT [fp_relT, eval_domT, eval_domT], eval_domT --> fpT, fp_relT] ---> fp_relT)
+  end;
+
+fun mk_cong_locale rel eval Retr =
+  Const (@{const_name cong}, mk_predT (map fastype_of [rel, eval, Retr]));
+
+fun derive_cong_locale ctxt rel eval Retr0 tac =
+  let
+    val Retr = enforce_type ctxt domain_type (domain_type (fastype_of rel)) Retr0;
+    val goal = HOLogic.mk_Trueprop (list_comb (mk_cong_locale rel eval Retr, [rel, eval, Retr]));
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} => tac ctxt))
+    |> Thm.close_derivation
+  end;
+
+fun derive_cong_general fp_b version fpT dead_ssig_bnf dead_pre_bnf eval Retr equivp_Retr
+    Retr_coinduct eval_thm eval_core_transfer lthy =
+  let
+    val eval_domT = domain_type (fastype_of eval);
+
+    fun cong_locale_tac ctxt =
+      mk_cong_locale_tac ctxt (rel_mono_of_bnf dead_pre_bnf) (rel_map_of_bnf dead_pre_bnf)
+        equivp_Retr (rel_mono_of_bnf dead_ssig_bnf) (rel_map_of_bnf dead_ssig_bnf) eval_thm
+        eval_core_transfer;
+
+    val rel = mk_rel1 lthy fpT fpT eval_domT dead_ssig_bnf;
+    val cong_rhs = list_comb (mk_gen_cong fpT eval_domT, [rel, eval]);
+    val ((_, cong_def), lthy) = lthy
+      |> define_const false fp_b version congN cong_rhs;
+
+    val cong_locale = derive_cong_locale lthy rel eval Retr cong_locale_tac;
+
+    val fold_cong_def = fold_thms lthy [cong_def];
+
+    fun instance_of_gen thm = fold_cong_def (thm OF [cong_locale]);
+
+    val cong_base = instance_of_gen @{thm cong.imp_gen_cong};
+    val cong_refl = instance_of_gen @{thm cong.gen_cong_reflp};
+    val cong_sym = instance_of_gen @{thm cong.gen_cong_symp};
+    val cong_trans = instance_of_gen @{thm cong.gen_cong_transp};
+
+    fun mk_cong_rho thm = thm RS instance_of_gen @{thm cong.gen_cong_rho};
+
+    val dtor_coinduct = @{thm predicate2I_obj} RS
+      (Retr_coinduct RS instance_of_gen @{thm cong.coinduction} RS @{thm predicate2D_obj});
+  in
+    (cong_def, cong_locale, cong_base, cong_refl, cong_sym, cong_trans, dtor_coinduct, mk_cong_rho,
+     lthy)
+  end;
+
+fun derive_cong_base fp_b version fpT dead_ssig_bnf ssig_fp_bnf_sugar dead_pre_bnf eval eval_thm
+    eval_core_transfer eval_VLeaf eval_sctr sctr_transfer Retr equivp_Retr Retr_coinduct lthy =
+  let
+    val (cong_def, cong_locale, cong_base, cong_refl, cong_sym, cong_trans, dtor_coinduct,
+         mk_cong_rho, lthy) =
+      derive_cong_general fp_b version fpT dead_ssig_bnf dead_pre_bnf eval Retr equivp_Retr
+        Retr_coinduct eval_thm eval_core_transfer lthy;
+
+    val dead_pre_map_id0 = map_id0_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp0 = map_comp0_of_bnf dead_pre_bnf;
+    val dead_pre_map_cong0 = map_cong0_of_bnf dead_pre_bnf;
+    val dead_pre_map_cong0' =
+      @{thm box_equals[OF _ o_apply[symmetric] id_apply[symmetric]]} RS dead_pre_map_cong0 RS ext;
+    val dead_pre_rel_map = rel_map_of_bnf dead_pre_bnf;
+
+    val ctor_alt_thm = eval_VLeaf RS (@{thm eq_comp_compI} OF [eval_sctr,
+      trans OF [dead_pre_map_comp0 RS sym, trans OF [dead_pre_map_cong0', dead_pre_map_id0]]]);
+
+    val cong_ctor_intro = mk_cong_rho ctor_alt_thm
+      |> unfold_thms lthy [o_apply]
+      |> (fn thm => sctr_transfer RS rel_funD RS thm)
+      |> unfold_thms lthy (id_apply :: dead_pre_rel_map @ #rel_injects ssig_fp_bnf_sugar);
+  in
+    ({cong_def = cong_def, cong_locale = cong_locale, cong_base = cong_base, cong_refl = cong_refl,
+      cong_sym = cong_sym, cong_trans = cong_trans, dtor_coinduct = dtor_coinduct,
+      cong_alg_intros = [cong_ctor_intro]}, lthy)
+  end;
+
+fun update_cong_alg_intros ctxt cong_def cong_locale old_cong_def old_cong_locale emb =
+  let
+    fun instance_of_gen thm = fold_thms ctxt [cong_def] (thm OF [cong_locale]);
+    fun instance_of_old_gen thm = fold_thms ctxt [old_cong_def] (thm OF [old_cong_locale]);
+
+    val emb_idem = @{thm ord_le_eq_trans} OF [emb, instance_of_gen @{thm cong.gen_cong_idem}];
+    fun mk_rel_mono bnf = instance_of_old_gen @{thm cong.leq_gen_cong} RS rel_mono_of_bnf bnf RS
+      @{thm predicate2D};
+    fun mk_intro bnf thm = mk_rel_mono bnf RS (@{thm predicate2D} OF [emb_idem, thm]);
+  in
+    map2 mk_intro
+  end
+
+fun derive_cong_step fp_b version fpT dead_ssig_bnf dead_pre_bnf eval eval_thm eval_core_transfer
+    old_dtor_coinduct_info algrho_def k_as_ssig_transfer Retr equivp_Retr Retr_coinduct
+    eval_embL embL_transfer old_all_dead_k_bnfs lthy =
+  let
+    val old_cong_def = #cong_def old_dtor_coinduct_info;
+    val old_cong_locale = #cong_locale old_dtor_coinduct_info;
+    val old_cong_alg_intros = #cong_alg_intros old_dtor_coinduct_info;
+
+    val (cong_def, cong_locale, cong_base, cong_refl, cong_sym, cong_trans, dtor_coinduct,
+         mk_cong_rho, lthy) =
+      derive_cong_general fp_b version fpT dead_ssig_bnf dead_pre_bnf eval Retr equivp_Retr
+        Retr_coinduct eval_thm eval_core_transfer lthy;
+
+    val cong_alg_intro =
+      k_as_ssig_transfer RS rel_funD RS mk_cong_rho (algrho_def RS meta_eq_to_obj_eq);
+
+    val gen_cong_emb =
+      (@{thm gen_cong_emb} OF [old_cong_locale, cong_locale, eval_embL, embL_transfer])
+      |> fold_thms lthy [old_cong_def, cong_def];
+
+    val cong_alg_intros = update_cong_alg_intros lthy cong_def cong_locale old_cong_def
+      old_cong_locale gen_cong_emb old_all_dead_k_bnfs old_cong_alg_intros;
+  in
+    ({cong_def = cong_def, cong_locale = cong_locale, cong_base = cong_base, cong_refl = cong_refl,
+      cong_sym = cong_sym, cong_trans = cong_trans, dtor_coinduct = dtor_coinduct,
+      cong_alg_intros = cong_alg_intro :: cong_alg_intros}, lthy)
+  end;
+
+fun derive_cong_merge fp_b version fpT old1_friend_names old2_friend_names dead_ssig_bnf
+    dead_pre_bnf eval eval_thm eval_core_transfer old1_dtor_coinduct_info old2_dtor_coinduct_info
+    Retr equivp_Retr Retr_coinduct eval_embLL embLL_transfer eval_embLR embLR_transfer
+    old1_all_dead_k_bnfs old2_all_dead_k_bnfs lthy =
+  let
+    val old1_cong_def = #cong_def old1_dtor_coinduct_info;
+    val old1_cong_locale = #cong_locale old1_dtor_coinduct_info;
+    val old1_cong_alg_intros = #cong_alg_intros old1_dtor_coinduct_info;
+    val old2_cong_def = #cong_def old2_dtor_coinduct_info;
+    val old2_cong_locale = #cong_locale old2_dtor_coinduct_info;
+    val old2_cong_alg_intros = #cong_alg_intros old2_dtor_coinduct_info;
+
+    val (cong_def, cong_locale, cong_base, cong_refl, cong_sym, cong_trans, dtor_coinduct, _,
+         lthy) =
+      derive_cong_general fp_b version fpT dead_ssig_bnf dead_pre_bnf eval Retr equivp_Retr
+        Retr_coinduct eval_thm eval_core_transfer lthy;
+
+    val emb1 = (@{thm gen_cong_emb} OF [old1_cong_locale, cong_locale, eval_embLL, embLL_transfer])
+      |> fold_thms lthy [old1_cong_def, cong_def];
+    val emb2 = (@{thm gen_cong_emb} OF [old2_cong_locale, cong_locale, eval_embLR, embLR_transfer])
+      |> fold_thms lthy [old2_cong_def, cong_def];
+
+    val cong_alg_intros1 = update_cong_alg_intros lthy cong_def cong_locale old1_cong_def
+      old1_cong_locale emb1 old1_all_dead_k_bnfs old1_cong_alg_intros;
+    val cong_alg_intros2 = update_cong_alg_intros lthy cong_def cong_locale old2_cong_def
+      old2_cong_locale emb2 old2_all_dead_k_bnfs old2_cong_alg_intros;
+
+    val (cong_algrho_intros1, cong_ctor_intro1) = split_last cong_alg_intros1;
+    val (cong_algrho_intros2, _) = split_last cong_alg_intros2;
+    val (old1_all_rho_k_bnfs, old1_Sig_bnf) = split_last old1_all_dead_k_bnfs;
+    val (old2_all_rho_k_bnfs, _) = split_last old2_all_dead_k_bnfs;
+
+    val (friend_names, (cong_algrho_intros, all_rho_k_bnfs)) =
+      merge_lists (op = o apply2 fst)
+        (old1_friend_names ~~ (cong_algrho_intros1 ~~ old1_all_rho_k_bnfs))
+        (old2_friend_names ~~ (cong_algrho_intros2 ~~ old2_all_rho_k_bnfs))
+      |> split_list ||> split_list;
+  in
+    (({cong_def = cong_def, cong_locale = cong_locale, cong_base = cong_base, cong_refl = cong_refl,
+       cong_sym = cong_sym, cong_trans = cong_trans, dtor_coinduct = dtor_coinduct,
+       cong_alg_intros = cong_algrho_intros @ [cong_ctor_intro1]}, all_rho_k_bnfs @ [old1_Sig_bnf],
+       friend_names), lthy)
+  end;
+
+fun derive_corecUU_base fpT_name lthy =
+  let
+    val fp_sugar as {T = Type (_, fpT_args0), pre_bnf, fp_bnf, fp_res, ...} =
+      checked_fp_sugar_of lthy fpT_name;
+    val num_fp_tyargs = length fpT_args0;
+    val fp_alives = liveness_of_fp_bnf num_fp_tyargs fp_bnf;
+
+    val (((Es, Fs0), [Y, Z]), names_lthy) = lthy
+      |> mk_TFrees num_fp_tyargs
+      ||>> mk_TFrees num_fp_tyargs
+      ||>> mk_TFrees 2;
+    val Fs = @{map 3} (fn alive => fn E => fn F => if alive then F else E) fp_alives Es Fs0;
+
+    val As = Es @ [Y];
+    val Bs = Es @ [Z];
+
+    val live_EsFs = filter (op <>) (Es ~~ Fs);
+    val live_AsBs = live_EsFs @ [(Y, Z)];
+    val fTs = map (op -->) live_EsFs;
+    val RTs = map (uncurry mk_pred2T) live_EsFs;
+    val live = length live_EsFs;
+
+    val ((((((x, fs), f), g), Rs), R), names_lthy) = names_lthy
+      |> yield_singleton (mk_Frees "x") Y
+      ||>> mk_Frees "f" fTs
+      ||>> yield_singleton (mk_Frees "f") (Y --> Z)
+      ||>> yield_singleton (mk_Frees "g") (Y --> Z)
+      ||>> mk_Frees "R" RTs
+      ||>> yield_singleton (mk_Frees "R") (mk_pred2T Y Z);
+
+    val ctor = mk_ctor Es (the_single (#ctors fp_res));
+    val dtor = mk_dtor Es (the_single (#dtors fp_res));
+
+    val fpT = Type (fpT_name, Es);
+    val preT = pre_type_of_ctor Y ctor;
+
+    val ((fp_b, version), lthy) = lthy |> get_name_next_version_of fpT_name;
+
+    val ((sig_fp_sugar, ssig_fp_sugar), lthy) = lthy
+      |> define_sig_type fp_b version fp_alives Es Y preT
+      ||>> define_ssig_type fp_b version fp_alives Es Y fpT;
+
+    val sig_bnf = #fp_bnf sig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+
+    val (((dead_pre_bnf, dead_sig_bnf), dead_ssig_bnf), lthy) = lthy
+      |> bnf_kill_all_but 1 pre_bnf
+      ||>> bnf_kill_all_but 1 sig_bnf
+      ||>> bnf_kill_all_but 1 ssig_bnf;
+
+    val sig_fp_ctr_sugar = #fp_ctr_sugar sig_fp_sugar;
+    val ssig_fp_ctr_sugar = #fp_ctr_sugar ssig_fp_sugar;
+
+    val sig_fp_bnf_sugar = #fp_bnf_sugar sig_fp_sugar;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val ssig_fp_induct_sugar = #fp_co_induct_sugar ssig_fp_sugar;
+
+    val sig_ctr_sugar = #ctr_sugar sig_fp_ctr_sugar;
+    val ssig_ctr_sugar = #ctr_sugar ssig_fp_ctr_sugar;
+
+    val sig_T_name = fst (dest_Type (#T sig_fp_sugar));
+    val ssig_T_name = fst (dest_Type (#T ssig_fp_sugar));
+
+    val sig_T = Type (sig_T_name, As);
+    val ssig_T = Type (ssig_T_name, As);
+
+    val pre_map = mk_mapN lthy live_AsBs preT pre_bnf;
+    val pre_rel = mk_relN lthy live_AsBs preT pre_bnf;
+    val dead_pre_map = mk_map1 lthy Y Z preT dead_pre_bnf;
+    val fp_rel = mk_relN lthy live_EsFs fpT fp_bnf;
+    val dtor_unfold = mk_co_rec (Proof_Context.theory_of lthy) Greatest_FP [Z] fpT
+      (the_single (#xtor_un_folds fp_res));
+    val Sig = mk_ctr As (the_single (#ctrs sig_ctr_sugar));
+    val unsig = mk_disc_or_sel As (the_single (the_single (#selss sig_ctr_sugar)));
+    val sig_rel = mk_relN lthy live_AsBs sig_T sig_bnf;
+    val dead_sig_map = mk_map 1 As Bs (map_of_bnf dead_sig_bnf);
+    val [Oper, VLeaf, CLeaf] = map (mk_ctr As) (#ctrs ssig_ctr_sugar);
+    val ssig_map = mk_mapN lthy live_AsBs ssig_T ssig_bnf;
+    val ssig_rel = mk_relN lthy live_AsBs ssig_T ssig_bnf;
+    val dead_ssig_map = mk_map 1 As Bs (map_of_bnf dead_ssig_bnf);
+    val dead_ssig_rel = mk_rel 1 As Bs (rel_of_bnf dead_ssig_bnf);
+
+    val ((Lam, Lam_def), lthy) = lthy
+      |> define_Lam_base fp_b version Y Z preT ssig_T dead_pre_map Sig unsig dead_sig_map Oper
+        VLeaf;
+
+    val proto_sctr = Sig;
+
+    val pre_map_transfer = map_transfer_of_bnf pre_bnf;
+    val pre_rel_def = rel_def_of_bnf pre_bnf;
+    val dead_pre_map_id = map_id_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp = map_comp_of_bnf dead_pre_bnf;
+    val fp_rel_eq = rel_eq_of_bnf fp_bnf;
+    val [ctor_dtor] = #ctor_dtors fp_res;
+    val [dtor_ctor] = #dtor_ctors fp_res;
+    val [dtor_inject] = #dtor_injects fp_res;
+    val [dtor_unfold_thm] = #xtor_un_fold_thms fp_res;
+    val [dtor_unfold_unique] = #xtor_un_fold_uniques fp_res;
+    val [dtor_unfold_transfer] = #xtor_un_fold_transfers fp_res;
+    val [dtor_rel_thm] = #xtor_rels fp_res;
+    val unsig_thm = the_single (the_single (#sel_thmss sig_ctr_sugar));
+    val [sig_map_thm] = #map_thms sig_fp_bnf_sugar;
+    val [Oper_map_thm, VLeaf_map_thm, CLeaf_map_thm] = #map_thms ssig_fp_bnf_sugar;
+    val sig_map_transfer = map_transfer_of_bnf sig_bnf;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val ssig_map_transfer = map_transfer_of_bnf ssig_bnf;
+    val ssig_induct = the_single (#co_inducts ssig_fp_induct_sugar);
+
+    val dtor_transfer = derive_dtor_transfer lthy live_EsFs Y Z pre_rel fp_rel Rs dtor dtor_rel_thm;
+    val preT_rel_eqs = map rel_eq_of_bnf (map_filter (bnf_of lthy) (add_type_namesT preT []));
+
+    val Sig_transfer = derive_sig_transfer I lthy live_AsBs pre_rel sig_rel Rs R Sig pre_rel_def
+      preT_rel_eqs (the_single (#ctr_transfers sig_fp_ctr_sugar));
+    val proto_sctr_transfer = Sig_transfer;
+    val unsig_transfer = derive_sig_transfer swap lthy live_AsBs pre_rel sig_rel Rs R unsig
+      pre_rel_def preT_rel_eqs (the_single (#sel_transfers sig_fp_ctr_sugar));
+    val Lam_transfer = derive_Lam_or_eval_core_transfer lthy live_AsBs Y Z preT ssig_T Rs R pre_rel
+      sig_rel ssig_rel Lam Lam_def []
+      [pre_map_transfer, sig_map_transfer, Sig_transfer, unsig_transfer];
+
+    val ((((((((flat, _, flat_simps), flat_transfer),
+            ((eval_core, _, eval_core_simps), eval_core_transfer)), (eval, eval_def)),
+          (cutSsig, cutSsig_def)), (algLam, algLam_def)), (corecU, corecU_def)), lthy) = lthy
+      |> define_flat_etc fp_b version live_AsBs Y Z preT fpT sig_T ssig_T Oper VLeaf CLeaf pre_rel
+        dead_pre_map dtor dtor_unfold dead_sig_map ssig_rel dead_ssig_map Lam Rs R pre_map_transfer
+        [fp_rel_eq] sig_map_transfer ssig_map_transfer Lam_transfer dtor_transfer;
+
+    val (Sig_pointful_natural, flat_pointful_natural, _, Lam_pointful_natural, _,
+         eval_core_pointful_natural, eval_thm, eval_flat, eval_simps as [eval_Oper, eval_VLeaf, _],
+         corecU_ctor, corecU_unique, dtor_algLam) =
+      derive_Sig_natural_etc lthy live live_AsBs Y Z preT fpT fpT sig_T ssig_T pre_map dead_pre_map
+        ctor dtor Sig dead_sig_map Oper VLeaf CLeaf ssig_map dead_ssig_map Lam flat eval_core eval
+        cutSsig algLam corecU x fs f g ctor_dtor dtor_inject dtor_unfold_thm dtor_unfold_unique
+        sig_map_thm ssig_induct ssig_map_thms Oper_map_thm VLeaf_map_thm CLeaf_map_thm Lam_transfer
+        flat_simps flat_transfer eval_core_simps eval_core_transfer eval_def cutSsig_def algLam_def
+        corecU_def pre_bnf pre_bnf dead_pre_bnf fp_bnf sig_bnf ssig_bnf dead_ssig_bnf;
+
+    val proto_sctr_pointful_natural = Sig_pointful_natural;
+
+    val algLam_thm = derive_algLam_base lthy Y Z preT fpT dead_pre_map ctor dtor algLam proto_sctr
+      dead_pre_map_id dead_pre_map_comp ctor_dtor dtor_ctor dtor_unfold_unique unsig_thm
+      Sig_pointful_natural ssig_map_thms Lam_def flat_simps eval_core_simps eval_thm algLam_def;
+
+    val (((corecUU, _), corecUU_thm, corecUU_unique, corecUU_transfer, eval_sctr, sctr_transfer,
+          sctr_pointful_natural), lthy) = lthy
+      |> define_corecUU_etc fp_b version live_AsBs Y Z preT fpT ssig_T pre_map dead_pre_map pre_rel
+        fp_rel ctor Oper ssig_map dead_ssig_map ssig_rel proto_sctr flat eval_core eval corecU fs f
+        g Rs R pre_map_transfer [] dtor_unfold_transfer dtor_transfer ssig_map_transfer
+        proto_sctr_transfer proto_sctr_pointful_natural flat_transfer flat_pointful_natural
+        eval_core_transfer eval_core_pointful_natural eval_thm eval_flat eval_Oper algLam_thm
+        cutSsig_def corecU_def corecU_ctor corecU_unique pre_bnf dead_pre_bnf fp_res ssig_fp_sugar;
+
+    val (Retr, equivp_Retr, Retr_coinduct) = lthy
+      |> derive_Retr fp_sugar fpT dead_pre_bnf ctor dtor names_lthy;
+
+    val (dtor_coinduct_info, lthy) = lthy
+      |> derive_cong_base fp_b version fpT dead_ssig_bnf ssig_fp_bnf_sugar dead_pre_bnf eval
+      eval_thm eval_core_transfer eval_VLeaf eval_sctr sctr_transfer Retr equivp_Retr Retr_coinduct;
+
+    val buffer =
+      {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = Sig, friends = Symtab.empty};
+
+    val notes =
+      [(corecUU_transferN, [corecUU_transfer])] @
+      (if Config.get lthy bnf_internals then
+         [(algLamN, [algLam_thm]),
+          (cong_alg_introsN, #cong_alg_intros dtor_coinduct_info),
+          (cong_localeN, [#cong_locale dtor_coinduct_info]),
+          (corecU_ctorN, [corecU_ctor]),
+          (corecU_uniqueN, [corecU_unique]),
+          (corecUUN, [corecUU_thm]),
+          (corecUU_uniqueN, [corecUU_unique]),
+          (dtor_algLamN, [dtor_algLam]),
+          (dtor_coinductN, [#dtor_coinduct dtor_coinduct_info]),
+          (dtor_transferN, [dtor_transfer]),
+          (equivp_RetrN, [equivp_Retr]),
+          (evalN, [eval_thm]),
+          (eval_core_pointful_naturalN, [eval_core_pointful_natural]),
+          (eval_core_transferN, [eval_core_transfer]),
+          (eval_flatN, [eval_flat]),
+          (eval_simpsN, eval_simps),
+          (flat_pointful_naturalN, [flat_pointful_natural]),
+          (flat_transferN, [flat_transfer]),
+          (Lam_pointful_naturalN, [Lam_pointful_natural]),
+          (Lam_transferN, [Lam_transfer]),
+          (proto_sctr_pointful_naturalN, [proto_sctr_pointful_natural]),
+          (proto_sctr_transferN, [proto_sctr_transfer]),
+          (Retr_coinductN, [Retr_coinduct]),
+          (sctr_pointful_naturalN, [sctr_pointful_natural]),
+          (sctr_transferN, [sctr_transfer]),
+          (Sig_pointful_naturalN, [Sig_pointful_natural])]
+        else
+          [])
+      |> map (fn (thmN, thms) =>
+        ((mk_version_fp_binding true lthy version fp_b thmN, []), [(thms, [])]));
+  in
+    ({fp_b = fp_b, version = version, fpT = fpT, Y = Y, Z = Z, friend_names = [],
+      sig_fp_sugars = [sig_fp_sugar], ssig_fp_sugar = ssig_fp_sugar, Lam = Lam,
+      proto_sctr = proto_sctr, flat = flat, eval_core = eval_core, eval = eval, algLam = algLam,
+      corecUU = corecUU, dtor_transfer = dtor_transfer, Lam_transfer = Lam_transfer,
+      Lam_pointful_natural = Lam_pointful_natural, proto_sctr_transfer = proto_sctr_transfer,
+      flat_simps = flat_simps, eval_core_simps = eval_core_simps, eval_thm = eval_thm,
+      eval_simps = eval_simps, all_algLam_algs = [algLam_thm], algLam_thm = algLam_thm,
+      dtor_algLam = dtor_algLam, corecUU_thm = corecUU_thm, corecUU_unique = corecUU_unique,
+      corecUU_transfer = corecUU_transfer, buffer = buffer, all_dead_k_bnfs = [dead_pre_bnf],
+      Retr = Retr, equivp_Retr = equivp_Retr, Retr_coinduct = Retr_coinduct,
+      dtor_coinduct_info = dtor_coinduct_info}
+     |> morph_corec_info (Local_Theory.target_morphism lthy),
+     lthy |> Local_Theory.notes notes |> snd)
+  end;
+
+fun derive_corecUU_step (fpT as Type (fpT_name, res_Ds))
+    ({friend_names = old_friend_names, sig_fp_sugars = old_sig_fp_sugars as old_sig_fp_sugar :: _,
+      ssig_fp_sugar = old_ssig_fp_sugar, Lam = old_Lam0, proto_sctr = old_proto_sctr0,
+      flat = old_flat0, eval_core = old_eval_core0, eval = old_eval0, algLam = old_algLam0,
+      dtor_transfer, Lam_transfer = old_Lam_transfer,
+      Lam_pointful_natural = old_Lam_pointful_natural,
+      proto_sctr_transfer = old_proto_sctr_transfer, flat_simps = old_flat_simps,
+      eval_core_simps = old_eval_core_simps, eval_thm = old_eval_thm,
+      all_algLam_algs = old_all_algLam_algs, algLam_thm = old_algLam_thm,
+      dtor_algLam = old_dtor_algLam, buffer = old_buffer, all_dead_k_bnfs = old_all_dead_k_bnfs,
+      Retr = old_Retr0, equivp_Retr, Retr_coinduct, dtor_coinduct_info = old_dtor_coinduct_info,
+      ...} : corec_info)
+    friend_name friend_T fp_b version Y Z k_T dead_k_bnf sig_fp_sugar ssig_fp_sugar rho rho_transfer
+    lthy =
+  let
+    val {pre_bnf = live_pre_bnf, fp_bnf = live_fp_bnf, fp_res, ...} =
+      checked_fp_sugar_of lthy fpT_name;
+
+    val names_lthy = lthy
+      |> fold Variable.declare_typ [Y, Z];
+
+    (* FIXME *)
+    val live_EsFs = [];
+    val live_AsBs = live_EsFs @ [(Y, Z)];
+    val live = length live_EsFs;
+
+    val ((((x, f), g), R), _) = names_lthy
+      |> yield_singleton (mk_Frees "x") Y
+      ||>> yield_singleton (mk_Frees "f") (Y --> Z)
+      ||>> yield_singleton (mk_Frees "g") (Y --> Z)
+      ||>> yield_singleton (mk_Frees "R") (mk_pred2T Y Z);
+
+    (* FIXME *)
+    val fs = [];
+    val Rs = [];
+
+    val ctor = mk_ctor res_Ds (the_single (#ctors fp_res));
+    val dtor = mk_dtor res_Ds (the_single (#dtors fp_res));
+
+    val friend_names = friend_name :: old_friend_names;
+
+    val old_sig_bnf = #fp_bnf old_sig_fp_sugar;
+    val old_ssig_bnf = #fp_bnf old_ssig_fp_sugar;
+    val sig_bnf = #fp_bnf sig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+
+    val ((((((dead_pre_bnf, dead_fp_bnf), dead_old_sig_bnf), dead_old_ssig_bnf), dead_sig_bnf),
+          dead_ssig_bnf), lthy) = lthy
+      |> bnf_kill_all_but 1 live_pre_bnf
+      ||>> bnf_kill_all_but 0 live_fp_bnf
+      ||>> bnf_kill_all_but 1 old_sig_bnf
+      ||>> bnf_kill_all_but 1 old_ssig_bnf
+      ||>> bnf_kill_all_but 1 sig_bnf
+      ||>> bnf_kill_all_but 1 ssig_bnf;
+
+    (* FIXME *)
+    val pre_bnf = dead_pre_bnf;
+    val fp_bnf = dead_fp_bnf;
+
+    val old_ssig_fp_ctr_sugar = #fp_ctr_sugar old_ssig_fp_sugar;
+    val sig_fp_ctr_sugar = #fp_ctr_sugar sig_fp_sugar;
+    val ssig_fp_ctr_sugar = #fp_ctr_sugar ssig_fp_sugar;
+
+    val sig_fp_bnf_sugar = #fp_bnf_sugar sig_fp_sugar;
+    val old_ssig_fp_bnf_sugar = #fp_bnf_sugar old_ssig_fp_sugar;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val old_ssig_fp_induct_sugar = #fp_co_induct_sugar old_ssig_fp_sugar;
+    val ssig_fp_induct_sugar = #fp_co_induct_sugar ssig_fp_sugar;
+
+    val old_ssig_ctr_sugar = #ctr_sugar old_ssig_fp_ctr_sugar;
+    val sig_ctr_sugar = #ctr_sugar sig_fp_ctr_sugar;
+    val ssig_ctr_sugar = #ctr_sugar ssig_fp_ctr_sugar;
+
+    val old_sig_T_name = fst (dest_Type (#T old_sig_fp_sugar));
+    val old_ssig_T_name = fst (dest_Type (#T old_ssig_fp_sugar));
+    val sig_T_name = fst (dest_Type (#T sig_fp_sugar));
+    val ssig_T_name = fst (dest_Type (#T ssig_fp_sugar));
+
+    val res_As = res_Ds @ [Y];
+    val res_Bs = res_Ds @ [Z];
+    val preT = pre_type_of_ctor Y ctor;
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val old_sig_T = Type (old_sig_T_name, res_As);
+    val old_ssig_T = Type (old_ssig_T_name, res_As);
+    val sig_T = Type (sig_T_name, res_As);
+    val ssig_T = Type (ssig_T_name, res_As);
+    val old_Lam_domT = Tsubst Y YpreT old_sig_T;
+    val old_eval_core_domT = Tsubst Y YpreT old_ssig_T;
+
+    val pre_map = mk_mapN lthy live_AsBs preT pre_bnf;
+    val pre_rel = mk_relN lthy live_AsBs preT pre_bnf;
+    val dead_pre_map = mk_map1 lthy Y Z preT dead_pre_bnf;
+    val dead_pre_rel = mk_rel1 lthy Y Z preT dead_pre_bnf;
+    val fp_rel = mk_relN lthy live_EsFs fpT fp_bnf;
+    val dtor_unfold = mk_co_rec (Proof_Context.theory_of lthy) Greatest_FP [Z] fpT
+      (the_single (#xtor_un_folds fp_res));
+    val dead_k_map = mk_map1 lthy Y Z k_T dead_k_bnf;
+    val Sig = mk_ctr res_As (the_single (#ctrs sig_ctr_sugar));
+    val unsig = mk_disc_or_sel res_As (the_single (the_single (#selss sig_ctr_sugar)));
+    val sig_rel = mk_relN lthy live_AsBs sig_T sig_bnf;
+    val dead_old_sig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old_sig_bnf);
+    val dead_sig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_sig_bnf);
+    val dead_sig_rel = mk_rel 1 res_As res_Bs (rel_of_bnf dead_sig_bnf);
+    val [old_Oper, old_VLeaf, old_CLeaf] = map (mk_ctr res_As) (#ctrs old_ssig_ctr_sugar);
+    val [Oper, VLeaf, CLeaf] = map (mk_ctr res_As) (#ctrs ssig_ctr_sugar);
+    val dead_old_ssig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old_ssig_bnf);
+    val ssig_map = mk_mapN lthy live_AsBs ssig_T ssig_bnf;
+    val ssig_rel = mk_relN lthy live_AsBs ssig_T ssig_bnf;
+    val dead_ssig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_ssig_bnf);
+    val dead_ssig_rel = mk_rel 1 res_As res_Bs (rel_of_bnf dead_ssig_bnf);
+    val old_Lam = enforce_type lthy domain_type old_Lam_domT old_Lam0;
+    val old_proto_sctr = enforce_type lthy domain_type preT old_proto_sctr0;
+    val old_flat = enforce_type lthy range_type old_ssig_T old_flat0;
+    val old_eval_core = enforce_type lthy domain_type old_eval_core_domT old_eval_core0;
+    val old_eval = enforce_type lthy range_type fpT old_eval0;
+    val old_algLam = enforce_type lthy range_type fpT old_algLam0;
+
+    val ((embL, embL_def, embL_simps), lthy) = lthy
+      |> define_embL embLN fp_b version Y Z fpT old_sig_T old_ssig_T k_T ssig_T Inl_const
+        dead_old_sig_map Sig old_Oper old_VLeaf old_CLeaf Oper VLeaf CLeaf;
+
+    val ((Lam, Lam_def), lthy) = lthy
+      |> define_Lam_step fp_b version Y Z preT old_ssig_T ssig_T dead_pre_map unsig rho embL
+        old_Lam;
+
+    val ((proto_sctr, proto_sctr_def), lthy) = lthy
+      |> define_proto_sctr_step_or_merge fp_b version old_sig_T k_T Sig old_proto_sctr;
+
+    val pre_map_comp = map_comp_of_bnf pre_bnf;
+    val pre_map_transfer = map_transfer_of_bnf pre_bnf;
+    val dead_pre_map_id = map_id_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp0 = map_comp0_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp = map_comp_of_bnf dead_pre_bnf;
+    val fp_map_id = map_id_of_bnf fp_bnf;
+    val fp_rel_eq = rel_eq_of_bnf fp_bnf;
+    val [ctor_dtor] = #ctor_dtors fp_res;
+    val [dtor_inject] = #dtor_injects fp_res;
+    val [dtor_unfold_thm] = #xtor_un_fold_thms fp_res;
+    val [dtor_unfold_unique] = #xtor_un_fold_uniques fp_res;
+    val [dtor_unfold_transfer] = #xtor_un_fold_transfers fp_res;
+    val fp_k_T_rel_eqs =
+      map rel_eq_of_bnf (map_filter (bnf_of lthy) (fold add_type_namesT [fpT, k_T] []));
+    val unsig_thm = the_single (the_single (#sel_thmss sig_ctr_sugar));
+    val [sig_map_thm] = #map_thms sig_fp_bnf_sugar;
+    val old_sig_map_comp = map_comp_of_bnf old_sig_bnf;
+    val old_sig_map_cong = map_cong_of_bnf old_sig_bnf;
+    val old_ssig_map_thms = #map_thms old_ssig_fp_bnf_sugar;
+    val [Oper_map_thm, VLeaf_map_thm, CLeaf_map_thm] = #map_thms ssig_fp_bnf_sugar;
+    val old_sig_map_transfer = map_transfer_of_bnf old_sig_bnf;
+    val sig_map_comp = map_comp_of_bnf sig_bnf;
+    val sig_map_transfer = map_transfer_of_bnf sig_bnf;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val ssig_map_transfer = map_transfer_of_bnf ssig_bnf;
+    val old_ssig_induct = the_single (#co_inducts old_ssig_fp_induct_sugar);
+    val ssig_induct = the_single (#co_inducts ssig_fp_induct_sugar);
+
+    val proto_sctr_transfer = derive_proto_sctr_transfer_step_or_merge lthy Y Z R dead_pre_rel
+      dead_sig_rel proto_sctr proto_sctr_def fp_k_T_rel_eqs [old_proto_sctr_transfer];
+    val embL_transfer = derive_transfer_by_transfer_prover lthy live_AsBs Rs R embL [embL_def]
+      fp_k_T_rel_eqs [old_sig_map_transfer];
+    val Lam_transfer = derive_Lam_or_eval_core_transfer lthy live_AsBs Y Z preT ssig_T Rs R pre_rel
+      sig_rel ssig_rel Lam Lam_def fp_k_T_rel_eqs
+      [pre_map_transfer, old_Lam_transfer, embL_transfer, rho_transfer];
+
+    val ((((((((flat, _, flat_simps), flat_transfer),
+            ((eval_core, _, eval_core_simps), eval_core_transfer)), (eval, eval_def)),
+          (cutSsig, cutSsig_def)), (algLam, algLam_def)), (corecU, corecU_def)), lthy) = lthy
+      |> define_flat_etc fp_b version live_AsBs Y Z preT fpT sig_T ssig_T Oper VLeaf CLeaf pre_rel
+        dead_pre_map dtor dtor_unfold dead_sig_map ssig_rel dead_ssig_map Lam Rs R pre_map_transfer
+        fp_k_T_rel_eqs sig_map_transfer ssig_map_transfer Lam_transfer dtor_transfer;
+
+    val (Sig_pointful_natural, flat_pointful_natural, Lam_natural_pointful, Lam_pointful_natural,
+         flat_VLeaf, eval_core_pointful_natural, eval_thm, eval_flat,
+         eval_simps as [eval_Oper, _, _], corecU_ctor, corecU_unique, dtor_algLam) =
+      derive_Sig_natural_etc lthy live live_AsBs Y Z preT fpT k_T sig_T ssig_T pre_map dead_pre_map
+        ctor dtor Sig dead_sig_map Oper VLeaf CLeaf ssig_map dead_ssig_map Lam flat eval_core eval
+        cutSsig algLam corecU x fs f g ctor_dtor dtor_inject dtor_unfold_thm dtor_unfold_unique
+        sig_map_thm ssig_induct ssig_map_thms Oper_map_thm VLeaf_map_thm CLeaf_map_thm Lam_transfer
+        flat_simps flat_transfer eval_core_simps eval_core_transfer eval_def cutSsig_def algLam_def
+        corecU_def live_pre_bnf pre_bnf dead_pre_bnf fp_bnf sig_bnf ssig_bnf dead_ssig_bnf;
+
+    val proto_sctr_natural = derive_natural_from_transfer_with_pre_type lthy live_AsBs Y Z preT
+      ssig_T pre_map ssig_map fs f proto_sctr proto_sctr_transfer [pre_bnf, sig_bnf] [];
+    val proto_sctr_pointful_natural = mk_pointful lthy proto_sctr_natural RS sym;
+
+    val (embL_pointful_natural, old_algLam_pointful, eval_embL, algLam_algLam) =
+      derive_embL_natural_etc lthy Inl_const old_ssig_bnf ssig_bnf Y Z preT fpT old_ssig_T ssig_T
+        dead_pre_map Sig dead_old_ssig_map embL old_algLam algLam old_flat flat old_eval_core
+        eval_core old_eval eval x f old_ssig_induct dead_pre_map_comp0 dead_pre_map_comp fp_map_id
+        dtor_inject dtor_unfold_unique Sig_pointful_natural unsig_thm sig_map_thm old_sig_map_comp
+        old_sig_map_cong old_ssig_map_thms old_Lam_pointful_natural Lam_def old_flat_simps
+        flat_simps embL_simps embL_transfer old_eval_core_simps eval_core_simps old_eval_thm
+        eval_thm old_dtor_algLam dtor_algLam old_algLam_thm;
+
+    val algLam_thm = derive_algLam_step_or_merge lthy Y fpT ctor proto_sctr algLam proto_sctr_def
+      old_algLam_pointful algLam_algLam;
+
+    val k_as_ssig = mk_k_as_ssig Z old_sig_T k_T ssig_T Sig dead_sig_map Oper VLeaf;
+    val k_as_ssig' = substT Y fpT k_as_ssig;
+
+    val algrho_rhs = HOLogic.mk_comp (eval, k_as_ssig');
+    val ((algrho, algrho_def), lthy) = lthy
+      |> define_const true fp_b version algrhoN algrho_rhs;
+
+    val k_as_ssig_transfer = derive_transfer_by_transfer_prover lthy live_AsBs Rs R k_as_ssig []
+      fp_k_T_rel_eqs [sig_map_transfer];
+
+    val k_as_ssig_natural = derive_natural_from_transfer lthy [(Y, Z)] [] [] f k_as_ssig
+      k_as_ssig_transfer [ssig_bnf] [dead_k_bnf];
+
+    val k_as_ssig_natural_pointful = mk_pointful lthy k_as_ssig_natural;
+
+    val [_, Lam_Inr] = derive_Lam_Inl_Inr lthy Y Z preT old_sig_T old_ssig_T k_T ssig_T
+      dead_pre_map Sig embL old_Lam Lam rho unsig_thm Lam_def;
+
+    val eval_core_k_as_ssig = derive_eval_core_k_as_ssig lthy Y preT k_T rho eval_core k_as_ssig x
+      pre_map_comp dead_pre_map_id sig_map_comp ssig_map_thms Lam_natural_pointful Lam_Inr
+      flat_VLeaf eval_core_simps;
+
+    val algLam_algrho = derive_algLam_algrho lthy Y fpT Sig algLam algrho algLam_def algrho_def;
+    val dtor_algrho = derive_dtor_algrho lthy Y Z preT fpT k_T ssig_T dead_pre_map dead_k_map dtor
+      rho eval algrho x eval_thm k_as_ssig_natural_pointful eval_core_k_as_ssig algrho_def;
+    val all_algLam_algs = algLam_algLam :: algLam_algrho :: old_all_algLam_algs;
+
+    val (((corecUU, _), corecUU_thm, corecUU_unique, corecUU_transfer, _, sctr_transfer,
+          sctr_pointful_natural), lthy) = lthy
+      |> define_corecUU_etc fp_b version live_AsBs Y Z preT fpT ssig_T pre_map dead_pre_map pre_rel
+        fp_rel ctor Oper ssig_map dead_ssig_map ssig_rel proto_sctr flat eval_core eval corecU fs f
+        g Rs R pre_map_transfer fp_k_T_rel_eqs dtor_unfold_transfer dtor_transfer ssig_map_transfer
+        proto_sctr_transfer proto_sctr_pointful_natural flat_transfer flat_pointful_natural
+        eval_core_transfer eval_core_pointful_natural eval_thm eval_flat eval_Oper algLam_thm
+        cutSsig_def corecU_def corecU_ctor corecU_unique pre_bnf dead_pre_bnf fp_res ssig_fp_sugar;
+
+    val (ctr_wrapper, friends) =
+      mk_ctr_wrapper_friends lthy friend_name friend_T old_sig_T k_T Sig old_buffer;
+
+    val Retr = enforce_type lthy (domain_type o domain_type) fpT old_Retr0;
+
+    val (dtor_coinduct_info, lthy) = lthy
+      |> derive_cong_step fp_b version fpT dead_ssig_bnf dead_pre_bnf eval eval_thm
+        eval_core_transfer old_dtor_coinduct_info algrho_def k_as_ssig_transfer Retr equivp_Retr
+        Retr_coinduct eval_embL embL_transfer old_all_dead_k_bnfs;
+
+    val buffer =
+      {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = ctr_wrapper, friends = friends};
+
+    val notes =
+      [(corecUU_transferN, [corecUU_transfer])] @
+      (if Config.get lthy bnf_internals then
+         [(algLamN, [algLam_thm]),
+          (algLam_algLamN, [algLam_algLam]),
+          (algLam_algrhoN, [algLam_algrho]),
+          (cong_alg_introsN, #cong_alg_intros dtor_coinduct_info),
+          (cong_localeN, [#cong_locale dtor_coinduct_info]),
+          (corecU_ctorN, [corecU_ctor]),
+          (corecU_uniqueN, [corecU_unique]),
+          (corecUUN, [corecUU_thm]),
+          (corecUU_uniqueN, [corecUU_unique]),
+          (dtor_algLamN, [dtor_algLam]),
+          (dtor_algrhoN, [dtor_algrho]),
+          (dtor_coinductN, [#dtor_coinduct dtor_coinduct_info]),
+          (embL_pointful_naturalN, [embL_pointful_natural]),
+          (embL_transferN, [embL_transfer]),
+          (evalN, [eval_thm]),
+          (eval_core_pointful_naturalN, [eval_core_pointful_natural]),
+          (eval_core_transferN, [eval_core_transfer]),
+          (eval_flatN, [eval_flat]),
+          (eval_simpsN, eval_simps),
+          (flat_pointful_naturalN, [flat_pointful_natural]),
+          (flat_transferN, [flat_transfer]),
+          (k_as_ssig_naturalN, [k_as_ssig_natural]),
+          (k_as_ssig_transferN, [k_as_ssig_transfer]),
+          (Lam_pointful_naturalN, [Lam_pointful_natural]),
+          (Lam_transferN, [Lam_transfer]),
+          (proto_sctr_pointful_naturalN, [proto_sctr_pointful_natural]),
+          (proto_sctr_transferN, [proto_sctr_transfer]),
+          (rho_transferN, [rho_transfer]),
+          (sctr_pointful_naturalN, [sctr_pointful_natural]),
+          (sctr_transferN, [sctr_transfer]),
+          (Sig_pointful_naturalN, [Sig_pointful_natural])]
+       else
+         [])
+      |> map (fn (thmN, thms) =>
+        ((mk_version_fp_binding true lthy version fp_b thmN, []), [(thms, [])]));
+
+    val phi = Local_Theory.target_morphism lthy;
+  in
+    (({fp_b = fp_b, version = version, fpT = fpT, Y = Y, Z = Z, friend_names = friend_names,
+       sig_fp_sugars = sig_fp_sugar :: old_sig_fp_sugars, ssig_fp_sugar = ssig_fp_sugar, Lam = Lam,
+       proto_sctr = proto_sctr, flat = flat, eval_core = eval_core, eval = eval, algLam = algLam,
+       corecUU = corecUU, dtor_transfer = dtor_transfer, Lam_transfer = Lam_transfer,
+       Lam_pointful_natural = Lam_pointful_natural, proto_sctr_transfer = proto_sctr_transfer,
+       flat_simps = flat_simps, eval_core_simps = eval_core_simps, eval_thm = eval_thm,
+       eval_simps = eval_simps, all_algLam_algs = all_algLam_algs, algLam_thm = algLam_thm,
+       dtor_algLam = dtor_algLam, corecUU_thm = corecUU_thm, corecUU_unique = corecUU_unique,
+       corecUU_transfer = corecUU_transfer, buffer = buffer,
+       all_dead_k_bnfs = dead_k_bnf :: old_all_dead_k_bnfs, Retr = Retr, equivp_Retr = equivp_Retr,
+       Retr_coinduct = Retr_coinduct, dtor_coinduct_info = dtor_coinduct_info}
+      |> morph_corec_info phi,
+      ({algrho = algrho, dtor_algrho = dtor_algrho, algLam_algrho = algLam_algrho}
+       |> morph_friend_info phi)),
+     lthy |> Local_Theory.notes notes |> snd)
+  end;
+
+fun derive_corecUU_merge (fpT as Type (fpT_name, res_Ds))
+    ({friend_names = old1_friend_names,
+      sig_fp_sugars = old1_sig_fp_sugars as old1_sig_fp_sugar :: _,
+      ssig_fp_sugar = old1_ssig_fp_sugar, Lam = old1_Lam0, proto_sctr = old1_proto_sctr0,
+      flat = old1_flat0, eval_core = old1_eval_core0, eval = old1_eval0, algLam = old1_algLam0,
+      dtor_transfer, Lam_transfer = old1_Lam_transfer,
+      Lam_pointful_natural = old1_Lam_pointful_natural,
+      proto_sctr_transfer = old1_proto_sctr_transfer, flat_simps = old1_flat_simps,
+      eval_core_simps = old1_eval_core_simps, eval_thm = old1_eval_thm,
+      all_algLam_algs = old1_all_algLam_algs, algLam_thm = old1_algLam_thm,
+      dtor_algLam = old1_dtor_algLam, buffer = old1_buffer, all_dead_k_bnfs = old1_all_dead_k_bnfs,
+      Retr = old1_Retr0, equivp_Retr, Retr_coinduct, dtor_coinduct_info = old1_dtor_coinduct_info,
+      ...} : corec_info)
+    ({friend_names = old2_friend_names,
+      sig_fp_sugars = old2_sig_fp_sugars as old2_sig_fp_sugar :: _,
+      ssig_fp_sugar = old2_ssig_fp_sugar, Lam = old2_Lam0, flat = old2_flat0,
+      eval_core = old2_eval_core0, eval = old2_eval0, algLam = old2_algLam0,
+      Lam_transfer = old2_Lam_transfer, Lam_pointful_natural = old2_Lam_pointful_natural,
+      flat_simps = old2_flat_simps, eval_core_simps = old2_eval_core_simps,
+      eval_thm = old2_eval_thm, all_algLam_algs = old2_all_algLam_algs,
+      algLam_thm = old2_algLam_thm, dtor_algLam = old2_dtor_algLam, buffer = old2_buffer,
+      all_dead_k_bnfs = old2_all_dead_k_bnfs, dtor_coinduct_info = old2_dtor_coinduct_info, ...}
+     : corec_info)
+    lthy =
+  let
+    val {pre_bnf = live_pre_bnf, fp_bnf = live_fp_bnf, fp_res, ...} =
+      checked_fp_sugar_of lthy fpT_name;
+    val num_fp_tyargs = length res_Ds;
+    val live_fp_alives = liveness_of_fp_bnf num_fp_tyargs live_fp_bnf;
+
+    val ((Ds, [Y, Z]), names_lthy) = lthy
+      |> mk_TFrees num_fp_tyargs
+      ||>> mk_TFrees 2;
+
+    (* FIXME *)
+    val live_EsFs = [];
+    val live_AsBs = live_EsFs @ [(Y, Z)];
+    val live = length live_EsFs;
+
+    val ((((x, f), g), R), _) = names_lthy
+      |> yield_singleton (mk_Frees "x") Y
+      ||>> yield_singleton (mk_Frees "f") (Y --> Z)
+      ||>> yield_singleton (mk_Frees "g") (Y --> Z)
+      ||>> yield_singleton (mk_Frees "R") (mk_pred2T Y Z);
+
+    (* FIXME *)
+    val fs = [];
+    val Rs = [];
+
+    val ctor = mk_ctor res_Ds (the_single (#ctors fp_res));
+    val dtor = mk_dtor res_Ds (the_single (#dtors fp_res));
+
+    val old1_sig_T_name = fst (dest_Type (#T old1_sig_fp_sugar));
+    val old2_sig_T_name = fst (dest_Type (#T old2_sig_fp_sugar));
+    val old1_ssig_T_name = fst (dest_Type (#T old1_ssig_fp_sugar));
+    val old2_ssig_T_name = fst (dest_Type (#T old2_ssig_fp_sugar));
+
+    val fp_alives = map (K false) live_fp_alives;
+
+    val As = Ds @ [Y];
+    val res_As = res_Ds @ [Y];
+    val res_Bs = res_Ds @ [Z];
+    val preT = pre_type_of_ctor Y ctor;
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val fpT0 = Type (fpT_name, Ds);
+    val old1_sig_T0 = Type (old1_sig_T_name, As);
+    val old2_sig_T0 = Type (old2_sig_T_name, As);
+    val old1_sig_T = Type (old1_sig_T_name, res_As);
+    val old2_sig_T = Type (old2_sig_T_name, res_As);
+    val old1_ssig_T = Type (old1_ssig_T_name, res_As);
+    val old2_ssig_T = Type (old2_ssig_T_name, res_As);
+    val old1_Lam_domT = Tsubst Y YpreT old1_sig_T;
+    val old2_Lam_domT = Tsubst Y YpreT old2_sig_T;
+    val old1_eval_core_domT = Tsubst Y YpreT old1_ssig_T;
+    val old2_eval_core_domT = Tsubst Y YpreT old2_ssig_T;
+
+    val ((fp_b, version), lthy) = lthy |> get_name_next_version_of fpT_name;
+
+    val ((sig_fp_sugar, ssig_fp_sugar), lthy) = lthy
+      |> define_sig_type fp_b version fp_alives Ds Y (mk_sumT (old1_sig_T0, old2_sig_T0))
+      ||>> define_ssig_type fp_b version fp_alives Ds Y fpT0;
+
+    val sig_T_name = fst (dest_Type (#T sig_fp_sugar));
+    val ssig_T_name = fst (dest_Type (#T ssig_fp_sugar));
+
+    val old1_sig_bnf = #fp_bnf old1_sig_fp_sugar;
+    val old2_sig_bnf = #fp_bnf old2_sig_fp_sugar;
+    val old1_ssig_bnf = #fp_bnf old1_ssig_fp_sugar;
+    val old2_ssig_bnf = #fp_bnf old2_ssig_fp_sugar;
+    val sig_bnf = #fp_bnf sig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+
+    val ((((((((dead_pre_bnf, dead_fp_bnf), dead_old1_sig_bnf), dead_old2_sig_bnf),
+        dead_old1_ssig_bnf), dead_old2_ssig_bnf), dead_sig_bnf), dead_ssig_bnf), lthy) = lthy
+      |> bnf_kill_all_but 1 live_pre_bnf
+      ||>> bnf_kill_all_but 0 live_fp_bnf
+      ||>> bnf_kill_all_but 1 old1_sig_bnf
+      ||>> bnf_kill_all_but 1 old2_sig_bnf
+      ||>> bnf_kill_all_but 1 old1_ssig_bnf
+      ||>> bnf_kill_all_but 1 old2_ssig_bnf
+      ||>> bnf_kill_all_but 1 sig_bnf
+      ||>> bnf_kill_all_but 1 ssig_bnf;
+
+    (* FIXME *)
+    val pre_bnf = dead_pre_bnf;
+    val fp_bnf = dead_fp_bnf;
+
+    val old1_ssig_fp_ctr_sugar = #fp_ctr_sugar old1_ssig_fp_sugar;
+    val old2_ssig_fp_ctr_sugar = #fp_ctr_sugar old2_ssig_fp_sugar;
+    val sig_fp_ctr_sugar = #fp_ctr_sugar sig_fp_sugar;
+    val ssig_fp_ctr_sugar = #fp_ctr_sugar ssig_fp_sugar;
+
+    val sig_fp_bnf_sugar = #fp_bnf_sugar sig_fp_sugar;
+    val old1_ssig_fp_bnf_sugar = #fp_bnf_sugar old1_ssig_fp_sugar;
+    val old2_ssig_fp_bnf_sugar = #fp_bnf_sugar old2_ssig_fp_sugar;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val old1_ssig_fp_induct_sugar = #fp_co_induct_sugar old1_ssig_fp_sugar;
+    val old2_ssig_fp_induct_sugar = #fp_co_induct_sugar old2_ssig_fp_sugar;
+    val ssig_fp_induct_sugar = #fp_co_induct_sugar ssig_fp_sugar;
+
+    val old1_ssig_ctr_sugar = #ctr_sugar old1_ssig_fp_ctr_sugar;
+    val old2_ssig_ctr_sugar = #ctr_sugar old2_ssig_fp_ctr_sugar;
+    val sig_ctr_sugar = #ctr_sugar sig_fp_ctr_sugar;
+    val ssig_ctr_sugar = #ctr_sugar ssig_fp_ctr_sugar;
+
+    val sig_T = Type (sig_T_name, res_As);
+    val ssig_T = Type (ssig_T_name, res_As);
+
+    val pre_map = mk_mapN lthy live_AsBs preT pre_bnf;
+    val pre_rel = mk_relN lthy live_AsBs preT pre_bnf;
+    val dead_pre_map = mk_map1 lthy Y Z preT dead_pre_bnf;
+    val dead_pre_rel = mk_rel1 lthy Y Z preT dead_pre_bnf;
+    val fp_rel = mk_relN lthy live_EsFs fpT fp_bnf;
+    val dtor_unfold = mk_co_rec (Proof_Context.theory_of lthy) Greatest_FP [Z] fpT
+      (the_single (#xtor_un_folds fp_res));
+    val Sig = mk_ctr res_As (the_single (#ctrs sig_ctr_sugar));
+    val unsig = mk_disc_or_sel res_As (the_single (the_single (#selss sig_ctr_sugar)));
+    val sig_rel = mk_relN lthy live_AsBs sig_T sig_bnf;
+    val dead_old1_sig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old1_sig_bnf);
+    val dead_old2_sig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old2_sig_bnf);
+    val dead_sig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_sig_bnf);
+    val dead_sig_rel = mk_rel 1 res_As res_Bs (rel_of_bnf dead_sig_bnf);
+    val [old1_Oper, old1_VLeaf, old1_CLeaf] = map (mk_ctr res_As) (#ctrs old1_ssig_ctr_sugar);
+    val [old2_Oper, old2_VLeaf, old2_CLeaf] = map (mk_ctr res_As) (#ctrs old2_ssig_ctr_sugar);
+    val [Oper, VLeaf, CLeaf] = map (mk_ctr res_As) (#ctrs ssig_ctr_sugar);
+    val old1_ssig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old1_ssig_bnf);
+    val old2_ssig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_old2_ssig_bnf);
+    val ssig_map = mk_mapN lthy live_AsBs ssig_T ssig_bnf;
+    val ssig_rel = mk_relN lthy live_AsBs ssig_T ssig_bnf;
+    val dead_ssig_map = mk_map 1 res_As res_Bs (map_of_bnf dead_ssig_bnf);
+    val old1_Lam = enforce_type lthy domain_type old1_Lam_domT old1_Lam0;
+    val old2_Lam = enforce_type lthy domain_type old2_Lam_domT old2_Lam0;
+    val old1_proto_sctr = enforce_type lthy domain_type preT old1_proto_sctr0;
+    val old1_flat = enforce_type lthy range_type old1_ssig_T old1_flat0;
+    val old2_flat = enforce_type lthy range_type old2_ssig_T old2_flat0;
+    val old1_eval_core = enforce_type lthy domain_type old1_eval_core_domT old1_eval_core0;
+    val old2_eval_core = enforce_type lthy domain_type old2_eval_core_domT old2_eval_core0;
+    val old1_eval = enforce_type lthy range_type fpT old1_eval0;
+    val old2_eval = enforce_type lthy range_type fpT old2_eval0;
+    val old1_algLam = enforce_type lthy range_type fpT old1_algLam0;
+    val old2_algLam = enforce_type lthy range_type fpT old2_algLam0;
+
+    val ((embLL, embLL_def, embLL_simps), lthy) = lthy
+      |> define_embL embLLN fp_b version Y Z fpT old1_sig_T old1_ssig_T old2_sig_T ssig_T Inl_const
+        dead_old1_sig_map Sig old1_Oper old1_VLeaf old1_CLeaf Oper VLeaf CLeaf;
+
+    val ((embLR, embLR_def, embLR_simps), lthy) = lthy
+      |> define_embL embLRN fp_b version Y Z fpT old2_sig_T old2_ssig_T old1_sig_T ssig_T
+        (fn T => fn U => Inr_const U T) dead_old2_sig_map Sig old2_Oper old2_VLeaf old2_CLeaf Oper
+        VLeaf CLeaf;
+
+    val ((Lam, Lam_def), lthy) = lthy
+      |> define_Lam_merge fp_b version Y Z preT old1_ssig_T old2_ssig_T ssig_T dead_pre_map unsig
+        embLL embLR old1_Lam old2_Lam;
+
+    val ((proto_sctr, proto_sctr_def), lthy) = lthy
+      |> define_proto_sctr_step_or_merge fp_b version old1_sig_T old2_sig_T Sig old1_proto_sctr;
+
+    val pre_map_transfer = map_transfer_of_bnf pre_bnf;
+    val dead_pre_map_comp0 = map_comp0_of_bnf dead_pre_bnf;
+    val dead_pre_map_comp = map_comp_of_bnf dead_pre_bnf;
+    val fp_map_id = map_id_of_bnf fp_bnf;
+    val fp_rel_eq = rel_eq_of_bnf fp_bnf;
+    val [ctor_dtor] = #ctor_dtors fp_res;
+    val [dtor_inject] = #dtor_injects fp_res;
+    val [dtor_unfold_thm] = #xtor_un_fold_thms fp_res;
+    val [dtor_unfold_unique] = #xtor_un_fold_uniques fp_res;
+    val [dtor_unfold_transfer] = #xtor_un_fold_transfers fp_res;
+    val unsig_thm = the_single (the_single (#sel_thmss sig_ctr_sugar));
+    val [sig_map_thm] = #map_thms sig_fp_bnf_sugar;
+    val old1_sig_map_comp = map_comp_of_bnf old1_sig_bnf;
+    val old2_sig_map_comp = map_comp_of_bnf old2_sig_bnf;
+    val old1_sig_map_cong = map_cong_of_bnf old1_sig_bnf;
+    val old2_sig_map_cong = map_cong_of_bnf old2_sig_bnf;
+    val old1_ssig_map_thms = #map_thms old1_ssig_fp_bnf_sugar;
+    val old2_ssig_map_thms = #map_thms old2_ssig_fp_bnf_sugar;
+    val [Oper_map_thm, VLeaf_map_thm, CLeaf_map_thm] = #map_thms ssig_fp_bnf_sugar;
+    val old1_sig_map_transfer = map_transfer_of_bnf old1_sig_bnf;
+    val old2_sig_map_transfer = map_transfer_of_bnf old2_sig_bnf;
+    val sig_map_transfer = map_transfer_of_bnf sig_bnf;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val ssig_map_transfer = map_transfer_of_bnf ssig_bnf;
+    val old1_ssig_induct = the_single (#co_inducts old1_ssig_fp_induct_sugar);
+    val old2_ssig_induct = the_single (#co_inducts old2_ssig_fp_induct_sugar);
+    val ssig_induct = the_single (#co_inducts ssig_fp_induct_sugar);
+
+    val proto_sctr_transfer = derive_proto_sctr_transfer_step_or_merge lthy Y Z R dead_pre_rel
+      dead_sig_rel proto_sctr proto_sctr_def [] [old1_proto_sctr_transfer];
+    val embLL_transfer = derive_transfer_by_transfer_prover lthy live_AsBs Rs R embLL [embLL_def] []
+      [old1_sig_map_transfer];
+    val embLR_transfer = derive_transfer_by_transfer_prover lthy live_AsBs Rs R embLR [embLR_def] []
+      [old2_sig_map_transfer];
+    val Lam_transfer = derive_Lam_or_eval_core_transfer lthy live_AsBs Y Z preT ssig_T Rs R
+      pre_rel sig_rel ssig_rel Lam Lam_def []
+      [pre_map_transfer, old1_Lam_transfer, old2_Lam_transfer, embLL_transfer, embLR_transfer];
+
+    val ((((((((flat, _, flat_simps), flat_transfer),
+            ((eval_core, _, eval_core_simps), eval_core_transfer)), (eval, eval_def)),
+          (cutSsig, cutSsig_def)), (algLam, algLam_def)), (corecU, corecU_def)), lthy) = lthy
+      |> define_flat_etc fp_b version live_AsBs Y Z preT fpT sig_T ssig_T Oper VLeaf CLeaf pre_rel
+        dead_pre_map dtor dtor_unfold dead_sig_map ssig_rel dead_ssig_map Lam Rs R pre_map_transfer
+        [fp_rel_eq] sig_map_transfer ssig_map_transfer Lam_transfer dtor_transfer;
+
+    val (Sig_pointful_natural, flat_pointful_natural, _, Lam_pointful_natural, _,
+         eval_core_pointful_natural, eval_thm, eval_flat, eval_simps as [eval_Oper, _, _],
+         corecU_ctor, corecU_unique, dtor_algLam) =
+      derive_Sig_natural_etc lthy live live_AsBs Y Z preT fpT fpT sig_T ssig_T pre_map dead_pre_map
+        ctor dtor Sig dead_sig_map Oper VLeaf CLeaf ssig_map dead_ssig_map Lam flat eval_core eval
+        cutSsig algLam corecU x fs f g ctor_dtor dtor_inject dtor_unfold_thm dtor_unfold_unique
+        sig_map_thm ssig_induct ssig_map_thms Oper_map_thm VLeaf_map_thm CLeaf_map_thm Lam_transfer
+        flat_simps flat_transfer eval_core_simps eval_core_transfer eval_def cutSsig_def algLam_def
+        corecU_def live_pre_bnf pre_bnf dead_pre_bnf fp_bnf sig_bnf ssig_bnf dead_ssig_bnf;
+
+    val proto_sctr_natural = derive_natural_from_transfer_with_pre_type lthy live_AsBs Y Z preT
+      ssig_T pre_map ssig_map fs f proto_sctr proto_sctr_transfer [pre_bnf, sig_bnf] [];
+    val proto_sctr_pointful_natural = mk_pointful lthy proto_sctr_natural RS sym;
+
+    val (embLL_pointful_natural, old1_algLam_pointful, eval_embLL, algLam_algLamL) =
+      derive_embL_natural_etc lthy Inl_const old1_ssig_bnf ssig_bnf Y Z preT fpT old1_ssig_T ssig_T
+        dead_pre_map Sig old1_ssig_map embLL old1_algLam algLam old1_flat flat old1_eval_core
+        eval_core old1_eval eval x f old1_ssig_induct dead_pre_map_comp0 dead_pre_map_comp fp_map_id
+        dtor_inject dtor_unfold_unique Sig_pointful_natural unsig_thm sig_map_thm old1_sig_map_comp
+        old1_sig_map_cong old1_ssig_map_thms old1_Lam_pointful_natural Lam_def old1_flat_simps
+        flat_simps embLL_simps embLL_transfer old1_eval_core_simps eval_core_simps old1_eval_thm
+        eval_thm old1_dtor_algLam dtor_algLam old1_algLam_thm;
+
+    val (embLR_pointful_natural, _, eval_embLR, algLam_algLamR) =
+      derive_embL_natural_etc lthy Inr_const old2_ssig_bnf ssig_bnf Y Z preT fpT old2_ssig_T ssig_T
+        dead_pre_map Sig old2_ssig_map embLR old2_algLam algLam old2_flat flat old2_eval_core
+        eval_core old2_eval eval x f old2_ssig_induct dead_pre_map_comp0 dead_pre_map_comp fp_map_id
+        dtor_inject dtor_unfold_unique Sig_pointful_natural unsig_thm sig_map_thm old2_sig_map_comp
+        old2_sig_map_cong old2_ssig_map_thms old2_Lam_pointful_natural Lam_def old2_flat_simps
+        flat_simps embLR_simps embLR_transfer old2_eval_core_simps eval_core_simps old2_eval_thm
+        eval_thm old2_dtor_algLam dtor_algLam old2_algLam_thm;
+
+    val algLam_thm = derive_algLam_step_or_merge lthy Y fpT ctor proto_sctr algLam proto_sctr_def
+      old1_algLam_pointful algLam_algLamL;
+
+    val all_algLam_algs = algLam_algLamL :: algLam_algLamR ::
+      merge_lists (Thm.eq_thm_prop o apply2 zero_var_indexes) old1_all_algLam_algs
+        old2_all_algLam_algs;
+
+    val (((corecUU, _), corecUU_thm, corecUU_unique, corecUU_transfer, _, sctr_transfer,
+          sctr_pointful_natural), lthy) = lthy
+      |> define_corecUU_etc fp_b version live_AsBs Y Z preT fpT ssig_T pre_map dead_pre_map pre_rel
+        fp_rel ctor Oper ssig_map dead_ssig_map ssig_rel proto_sctr flat eval_core eval corecU fs f
+        g Rs R pre_map_transfer [] dtor_unfold_transfer dtor_transfer ssig_map_transfer
+        proto_sctr_transfer proto_sctr_pointful_natural flat_transfer flat_pointful_natural
+        eval_core_transfer eval_core_pointful_natural eval_thm eval_flat eval_Oper algLam_thm
+        cutSsig_def corecU_def corecU_ctor corecU_unique pre_bnf dead_pre_bnf fp_res ssig_fp_sugar;
+
+    val Retr = enforce_type lthy (domain_type o domain_type) fpT old1_Retr0;
+
+    val embed_Sig_inl = embed_Sig lthy Sig (Inl_const old1_sig_T old2_sig_T);
+    val embed_Sig_inr = embed_Sig lthy Sig (Inr_const old1_sig_T old2_sig_T);
+
+    val ctr_wrapper = embed_Sig_inl (#ctr_wrapper old1_buffer);
+    val friends = Symtab.merge (K true)
+      (Symtab.map (K (apsnd embed_Sig_inl)) (#friends old1_buffer),
+       Symtab.map (K (apsnd embed_Sig_inr)) (#friends old2_buffer));
+
+    val old_fp_sugars =
+      merge_lists (op = o apply2 (fst o dest_Type o #T)) old1_sig_fp_sugars old2_sig_fp_sugars;
+
+    val ((dtor_coinduct_info, all_dead_k_bnfs, friend_names), lthy) = lthy
+      |> derive_cong_merge fp_b version fpT old1_friend_names old2_friend_names dead_ssig_bnf
+        dead_pre_bnf eval eval_thm eval_core_transfer old1_dtor_coinduct_info
+        old2_dtor_coinduct_info Retr equivp_Retr Retr_coinduct eval_embLL embLL_transfer eval_embLR
+        embLR_transfer old1_all_dead_k_bnfs old2_all_dead_k_bnfs;
+
+    val buffer =
+      {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = ctr_wrapper, friends = friends};
+
+    val notes =
+      [(corecUU_transferN, [corecUU_transfer])] @
+      (if Config.get lthy bnf_internals then
+         [(algLamN, [algLam_thm]),
+          (algLam_algLamN, [algLam_algLamL, algLam_algLamR]),
+          (cong_alg_introsN, #cong_alg_intros dtor_coinduct_info),
+          (cong_localeN, [#cong_locale dtor_coinduct_info]),
+          (corecU_ctorN, [corecU_ctor]),
+          (corecU_uniqueN, [corecU_unique]),
+          (corecUUN, [corecUU_thm]),
+          (corecUU_uniqueN, [corecUU_unique]),
+          (dtor_algLamN, [dtor_algLam]),
+          (dtor_coinductN, [#dtor_coinduct dtor_coinduct_info]),
+          (eval_core_pointful_naturalN, [eval_core_pointful_natural]),
+          (eval_core_transferN, [eval_core_transfer]),
+          (embL_pointful_naturalN, [embLL_pointful_natural, embLR_pointful_natural]),
+          (embL_transferN, [embLL_transfer, embLR_transfer]),
+          (evalN, [eval_thm]),
+          (eval_flatN, [eval_flat]),
+          (eval_simpsN, eval_simps),
+          (flat_pointful_naturalN, [flat_pointful_natural]),
+          (flat_transferN, [flat_transfer]),
+          (Lam_pointful_naturalN, [Lam_pointful_natural]),
+          (Lam_transferN, [Lam_transfer]),
+          (proto_sctr_pointful_naturalN, [proto_sctr_pointful_natural]),
+          (proto_sctr_transferN, [proto_sctr_transfer]),
+          (sctr_pointful_naturalN, [sctr_pointful_natural]),
+          (sctr_transferN, [sctr_transfer]),
+          (Sig_pointful_naturalN, [Sig_pointful_natural])]
+       else
+         [])
+      |> map (fn (thmN, thms) =>
+        ((mk_version_fp_binding true lthy version fp_b thmN, []), [(thms, [])]));
+  in
+    ({fp_b = fp_b, version = version, fpT = fpT, Y = Y, Z = Z, friend_names = friend_names,
+      sig_fp_sugars = sig_fp_sugar :: old_fp_sugars, ssig_fp_sugar = ssig_fp_sugar, Lam = Lam,
+      proto_sctr = proto_sctr, flat = flat, eval_core = eval_core, eval = eval, algLam = algLam,
+      corecUU = corecUU, dtor_transfer = dtor_transfer, Lam_transfer = Lam_transfer,
+      Lam_pointful_natural = Lam_pointful_natural, proto_sctr_transfer = proto_sctr_transfer,
+      flat_simps = flat_simps, eval_core_simps = eval_core_simps, eval_thm = eval_thm,
+      eval_simps = eval_simps, all_algLam_algs = all_algLam_algs, algLam_thm = algLam_thm,
+      dtor_algLam = dtor_algLam, corecUU_thm = corecUU_thm, corecUU_unique = corecUU_unique,
+      corecUU_transfer = corecUU_transfer, buffer = buffer, all_dead_k_bnfs = all_dead_k_bnfs,
+      Retr = Retr, equivp_Retr = equivp_Retr, Retr_coinduct = Retr_coinduct,
+      dtor_coinduct_info = dtor_coinduct_info}
+     |> morph_corec_info (Local_Theory.target_morphism lthy),
+     lthy |> Local_Theory.notes notes |> snd)
+  end;
+
+fun set_corec_info_exprs fpT_name f =
+  Local_Theory.declaration {syntax = false, pervasive = true} (fn phi =>
+    let val exprs = f phi in
+      Data.map (apsnd (fn [info_tab] => [Symtab.map_default (fpT_name, exprs) (K exprs) info_tab]))
+    end);
+
+fun subsume_corec_info_ad ctxt {fpT = fpT1, friend_names = friend_names1}
+    {fpT = fpT2, friend_names = friend_names2} =
+  Sign.typ_instance (Proof_Context.theory_of ctxt) (fpT1, fpT2) andalso
+  subset (op =) (friend_names1, friend_names2);
+
+fun subsume_corec_info_expr ctxt expr1 expr2 =
+  subsume_corec_info_ad ctxt (corec_ad_of_expr expr1) (corec_ad_of_expr expr2);
+
+fun instantiate_corec_info thy res_T (info as {fpT, ...}) =
+  let
+    val As_rho = tvar_subst thy [fpT] [res_T];
+    val substAT = Term.typ_subst_TVars As_rho;
+    val substA = Term.subst_TVars As_rho;
+    val phi = Morphism.typ_morphism "BNF" substAT $> Morphism.term_morphism "BNF" substA;
+  in
+    morph_corec_info phi info
+  end;
+
+fun instantiate_corec_info_expr thy res_T (Ad ({friend_names, ...}, f)) =
+    Ad ({fpT = res_T, friend_names = friend_names}, f #>> instantiate_corec_info thy res_T)
+  | instantiate_corec_info_expr thy res_T (Info info) =
+    Info (instantiate_corec_info thy res_T info);
+
+fun ensure_Info expr = corec_info_of_expr expr #>> Info
+and ensure_Info_if_Info old_expr (expr, lthy) =
+  if is_Info old_expr then ensure_Info expr lthy else (expr, lthy)
+and merge_corec_info_exprs old_exprs expr1 expr2 lthy =
+  if subsume_corec_info_expr lthy expr2 expr1 then
+    if subsume_corec_info_expr lthy expr1 expr2 andalso is_Ad expr1 then
+      (expr2, lthy)
+    else
+      ensure_Info_if_Info expr2 (expr1, lthy)
+  else if subsume_corec_info_expr lthy expr1 expr2 then
+    ensure_Info_if_Info expr1 (expr2, lthy)
+  else
+    let
+      val thy = Proof_Context.theory_of lthy;
+
+      val {fpT = fpT1, friend_names = friend_names1} = corec_ad_of_expr expr1;
+      val {fpT = fpT2, friend_names = friend_names2} = corec_ad_of_expr expr2;
+      val fpT0 = typ_unify_disjointly thy (fpT1, fpT2);
+
+      val fpT = singleton (freeze_types lthy []) fpT0;
+      val friend_names = merge_lists (op =) friend_names1 friend_names2;
+
+      val expr =
+        Ad ({fpT = fpT, friend_names = friend_names},
+          corec_info_of_expr expr1
+          ##>> corec_info_of_expr expr2
+          #-> uncurry (derive_corecUU_merge fpT));
+
+      val old_same_type_exprs =
+        if old_exprs then
+          []
+          |> Sign.typ_instance thy (fpT1, fpT0) ? cons expr1
+          |> Sign.typ_instance thy (fpT2, fpT0) ? cons expr2
+        else
+          [];
+    in
+      (expr, lthy) |> fold ensure_Info_if_Info old_same_type_exprs
+    end
+and insert_corec_info_expr expr exprs lthy =
+  let
+    val thy = Proof_Context.theory_of lthy;
+
+    val {fpT = new_fpT, ...} = corec_ad_of_expr expr;
+
+    val is_Tinst = curry (Sign.typ_instance thy);
+    fun is_Tequiv T U = is_Tinst T U andalso is_Tinst U T;
+
+    val (((equiv_exprs, sub_exprs), sup_exprs), incomp_exprs) = exprs
+      |> List.partition ((fn {fpT, ...} => is_Tequiv fpT new_fpT) o corec_ad_of_expr)
+      ||>> List.partition ((fn {fpT, ...} => is_Tinst fpT new_fpT) o corec_ad_of_expr)
+      ||>> List.partition ((fn {fpT, ...} => is_Tinst new_fpT fpT) o corec_ad_of_expr);
+
+    fun add_instantiated_incomp_expr expr exprs =
+      let val {fpT, ...} = corec_ad_of_expr expr in
+        (case try (typ_unify_disjointly thy) (fpT, new_fpT) of
+          SOME new_T =>
+          let val subsumes = (fn {fpT, ...} => is_Tinst new_T fpT) o corec_ad_of_expr in
+            if exists (exists subsumes) [exprs, sub_exprs] then exprs
+            else instantiate_corec_info_expr thy new_T expr :: exprs
+          end
+        | NONE => exprs)
+      end;
+
+    val unincomp_exprs = fold add_instantiated_incomp_expr incomp_exprs [];
+    val ((merged_sub_exprs, merged_unincomp_exprs), lthy) = lthy
+      |> fold_map (merge_corec_info_exprs true expr) sub_exprs
+      ||>> fold_map (merge_corec_info_exprs false expr) unincomp_exprs;
+    val (merged_equiv_expr, lthy) = (expr, lthy)
+      |> fold (uncurry o merge_corec_info_exprs true) equiv_exprs;
+  in
+    (merged_unincomp_exprs @ merged_sub_exprs @ merged_equiv_expr :: sup_exprs @ incomp_exprs
+     |> sort (rev_order o int_ord o apply2 (length o #friend_names o corec_ad_of_expr)),
+     lthy)
+  end
+and register_corec_info (info as {fpT = Type (fpT_name, _), ...}) lthy =
+  let
+    val (exprs, lthy) = insert_corec_info_expr (Info info) (corec_info_exprs_of lthy fpT_name) lthy;
+  in
+    lthy |> set_corec_info_exprs fpT_name (fn phi => map (morph_corec_info_expr phi) exprs)
+  end
+and corec_info_of_expr (Ad (_, f)) lthy = f lthy
+  | corec_info_of_expr (Info info) lthy = (info, lthy);
+
+fun nonempty_corec_info_exprs_of fpT_name lthy =
+  (case corec_info_exprs_of lthy fpT_name of
+    [] =>
+    derive_corecUU_base fpT_name lthy
+    |> (fn (info, lthy) =>
+      ([Info info], lthy
+         |> set_corec_info_exprs fpT_name (fn phi => [Info (morph_corec_info phi info)])))
+  | exprs => (exprs, lthy));
+
+fun corec_info_of res_T lthy =
+  (case res_T of
+    Type (fpT_name, _) =>
+    let
+      val (exprs, lthy) = nonempty_corec_info_exprs_of fpT_name lthy;
+      val thy = Proof_Context.theory_of lthy;
+      val SOME expr =
+        find_first ((fn {fpT, ...} => Sign.typ_instance thy (res_T, fpT)) o corec_ad_of_expr) exprs;
+      val (info, lthy) = corec_info_of_expr expr lthy;
+    in
+      (instantiate_corec_info thy res_T info, lthy |> is_Ad expr ? register_corec_info info)
+    end
+  | _ => not_codatatype lthy res_T);
+
+fun maybe_corec_info_of ctxt res_T =
+  (case res_T of
+    Type (fpT_name, _) =>
+    let
+      val thy = Proof_Context.theory_of ctxt;
+      val infos = corec_infos_of ctxt fpT_name;
+    in
+      find_first (fn {fpT, ...} => Sign.typ_instance thy (res_T, fpT)) infos
+      |> Option.map (instantiate_corec_info thy res_T)
+    end
+  | _ => not_codatatype ctxt res_T);
+
+fun prepare_friend_corec friend_name friend_T lthy =
+  let
+    val (arg_Ts, res_T) = strip_type friend_T;
+    val Type (fpT_name, res_Ds) =
+      (case res_T of
+        T as Type _ => T
+      | T => error (not_codatatype lthy T));
+
+    val _ = not (null arg_Ts) orelse
+      error "Function with no argument cannot be registered as friend";
+
+    val {pre_bnf, fp_bnf = live_fp_bnf, fp_res, ...} = checked_fp_sugar_of lthy fpT_name;
+    val num_fp_tyargs = length res_Ds;
+    val live_fp_alives = liveness_of_fp_bnf num_fp_tyargs live_fp_bnf;
+
+    val fpT_name = fst (dest_Type res_T);
+
+    val (old_info as {friend_names = old_friend_names, sig_fp_sugars = old_sig_fp_sugar :: _,
+           buffer = old_buffer, ...}, lthy) =
+      corec_info_of res_T lthy;
+    val old_sig_T_name = fst (dest_Type (#T old_sig_fp_sugar));
+    val old_sig_alives = liveness_of_fp_bnf (num_fp_tyargs + 1) (#fp_bnf old_sig_fp_sugar);
+
+    (* FIXME: later *)
+    val fp_alives = fst (split_last old_sig_alives);
+    val fp_alives = map (K false) live_fp_alives;
+
+    val _ = not (member (op =) old_friend_names friend_name) orelse
+      error ("Function " ^ quote (Syntax.string_of_term lthy (Const (friend_name, friend_T))) ^
+        " already registered as friend");
+
+    val lthy = lthy |> Variable.declare_typ friend_T;
+    val ((Ds, [Y, Z]), _) = lthy
+      |> mk_TFrees num_fp_tyargs
+      ||>> mk_TFrees 2;
+
+    (* FIXME *)
+    val dead_Ds = Ds;
+    val live_As = [Y];
+
+    val ctor = mk_ctor res_Ds (the_single (#ctors fp_res));
+
+    val fpT0 = Type (fpT_name, Ds);
+    val k_Ts0 = map (typ_subst_nonatomic (res_Ds ~~ Ds) o typ_subst_nonatomic [(res_T, Y)]) arg_Ts;
+    val k_T0 = mk_tupleT_balanced k_Ts0;
+
+    val As = Ds @ [Y];
+    val res_As = res_Ds @ [Y];
+
+    val k_As = fold Term.add_tfreesT k_Ts0 [];
+    val _ = (case filter_out (member (op =) As o TFree) k_As of [] => ()
+      | k_A :: _ => error ("Cannot have type variable " ^
+          quote (Syntax.string_of_typ lthy (TFree k_A)) ^ " used like that in friend"));
+
+    val substDT = Term.typ_subst_atomic (Ds ~~ res_Ds);
+
+    val old_sig_T0 = Type (old_sig_T_name, As);
+
+    val ((fp_b, version), lthy) = lthy |> get_name_next_version_of fpT_name;
+
+    val (((dead_k_bnf, sig_fp_sugar), ssig_fp_sugar), lthy) = lthy
+      |> bnf_with_deads_and_lives dead_Ds live_As Y fpT0 k_T0
+      ||>> define_sig_type fp_b version fp_alives Ds Y (mk_sumT (old_sig_T0, k_T0))
+      ||>> define_ssig_type fp_b version fp_alives Ds Y fpT0;
+
+    val _ = live_of_bnf dead_k_bnf = 1 orelse
+      error "Impossible type for friend (the result codatatype must occur live in the arguments)";
+
+    val (dead_pre_bnf, lthy) = lthy
+      |> bnf_kill_all_but 1 pre_bnf;
+
+    val sig_fp_ctr_sugar = #fp_ctr_sugar sig_fp_sugar;
+    val ssig_fp_ctr_sugar = #fp_ctr_sugar ssig_fp_sugar;
+
+    val sig_ctr_sugar = #ctr_sugar sig_fp_ctr_sugar;
+    val ssig_ctr_sugar = #ctr_sugar ssig_fp_ctr_sugar;
+
+    val ssig_T_name = fst (dest_Type (#T ssig_fp_sugar));
+
+    val preT = pre_type_of_ctor Y ctor;
+    val old_sig_T = substDT old_sig_T0;
+    val k_T = substDT k_T0;
+    val ssig_T = Type (ssig_T_name, res_As);
+
+    val Sig = mk_ctr res_As (the_single (#ctrs sig_ctr_sugar));
+
+    val [Oper, VLeaf, CLeaf] = map (mk_ctr res_As) (#ctrs ssig_ctr_sugar);
+    val (ctr_wrapper, friends) =
+      mk_ctr_wrapper_friends lthy friend_name friend_T old_sig_T k_T Sig old_buffer;
+
+    val buffer =
+      {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = ctr_wrapper, friends = friends};
+  in
+    ((old_info, fp_b, version, Y, Z, preT, k_T, ssig_T, dead_pre_bnf, dead_k_bnf, sig_fp_sugar,
+      ssig_fp_sugar, buffer), lthy)
+  end;
+
+fun register_friend_corec key fp_b version Y Z k_T dead_k_bnf sig_fp_sugar ssig_fp_sugar
+    friend_const rho rho_transfer old_info lthy =
+  let
+    val friend_T = fastype_of friend_const;
+    val res_T = body_type friend_T;
+  in
+    derive_corecUU_step res_T old_info key friend_T fp_b version Y Z k_T dead_k_bnf sig_fp_sugar
+      ssig_fp_sugar rho rho_transfer lthy
+    |> (fn ((info, friend_info), lthy) => (friend_info, register_corec_info info lthy))
+  end;
+
+fun merge_corec_info_exprss exprs1 exprs2 lthy =
+  let
+    fun all_friend_names_of exprs =
+      fold (union (op =)) (map (#friend_names o corec_ad_of_expr) exprs) [];
+
+    val friend_names1 = all_friend_names_of exprs1;
+    val friend_names2 = all_friend_names_of exprs2;
+  in
+    if subset (op =) (friend_names2, friend_names1) then
+      if subset (op =) (friend_names1, friend_names2) andalso
+         length (filter is_Info exprs2) > length (filter is_Info exprs1) then
+        (exprs2, lthy)
+      else
+        (exprs1, lthy)
+    else if subset (op =) (friend_names1, friend_names2) then
+      (exprs2, lthy)
+    else
+      fold_rev (uncurry o insert_corec_info_expr) exprs2 (exprs1, lthy)
+  end;
+
+fun merge_corec_info_tabs info_tab1 info_tab2 lthy =
+  let
+    val fpT_names = union (op =) (Symtab.keys info_tab1) (Symtab.keys info_tab2);
+
+    fun add_infos_of fpT_name (info_tab, lthy) =
+      (case Symtab.lookup info_tab1 fpT_name of
+        NONE =>
+        (Symtab.update_new (fpT_name, the (Symtab.lookup info_tab2 fpT_name)) info_tab, lthy)
+      | SOME exprs1 =>
+        (case Symtab.lookup info_tab2 fpT_name of
+          NONE => (Symtab.update_new (fpT_name, exprs1) info_tab, lthy)
+        | SOME exprs2 =>
+          let val (exprs, lthy) = merge_corec_info_exprss exprs1 exprs2 lthy in
+            (Symtab.update_new (fpT_name, exprs) info_tab, lthy)
+          end));
+  in
+    fold add_infos_of fpT_names (Symtab.empty, lthy)
+  end;
+
+fun consolidate lthy =
+  (case snd (Data.get (Context.Proof lthy)) of
+    [_] => raise Same.SAME
+  | info_tab :: info_tabs =>
+    let
+      val (info_tab', lthy) = fold_rev (uncurry o merge_corec_info_tabs) info_tabs (info_tab, lthy);
+    in
+      Local_Theory.declaration {syntax = false, pervasive = true} (fn phi =>
+          Data.map (apsnd (fn _ => [Symtab.map (K (map (morph_corec_info_expr phi))) info_tab'])))
+        lthy
+    end);
+
+fun consolidate_global thy =
+  SOME (Named_Target.theory_map consolidate thy)
+  handle Same.SAME => NONE;
+
+val _ = Theory.setup (Theory.at_begin consolidate_global);
+
+end;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec_sugar.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,2412 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec_sugar.ML
+    Author:     Aymeric Bouzy, Ecole polytechnique
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Author:     Dmitriy Traytel, ETH Zürich
+    Copyright   2015, 2016
+
+Generalized corecursor sugar ("corec" and friends).
+*)
+
+signature BNF_GFP_GREC_SUGAR =
+sig
+  datatype corec_option =
+    Plugins_Option of Proof.context -> Plugin_Name.filter |
+    Friend_Option |
+    Transfer_Option
+
+  val parse_corec_equation: Proof.context -> term list -> term -> term list * term
+  val explore_corec_equation: Proof.context -> bool -> bool -> string -> term ->
+    BNF_GFP_Grec_Sugar_Util.s_parse_info -> typ -> term list * term -> term list * term
+  val build_corecUU_arg_and_goals: bool -> term -> term list * term -> local_theory ->
+    (((thm list * thm list * thm list) * term list) * term) * local_theory
+  val derive_eq_corecUU: Proof.context -> BNF_GFP_Grec.corec_info -> term -> term -> thm -> thm
+  val derive_unique: Proof.context -> morphism -> term -> BNF_GFP_Grec.corec_info -> typ -> thm ->
+    thm
+
+  val corec_cmd: corec_option list -> (binding * string option * mixfix) list * string ->
+    local_theory -> local_theory
+  val corecursive_cmd: corec_option list -> (binding * string option * mixfix) list * string ->
+    local_theory -> Proof.state
+  val friend_of_corec_cmd: (string * string option) * string -> local_theory -> Proof.state
+  val coinduction_upto_cmd: string * string -> local_theory -> local_theory
+end;
+
+structure BNF_GFP_Grec_Sugar : BNF_GFP_GREC_SUGAR =
+struct
+
+open Ctr_Sugar
+open BNF_Util
+open BNF_Tactics
+open BNF_Def
+open BNF_Comp
+open BNF_FP_Util
+open BNF_FP_Def_Sugar
+open BNF_FP_N2M_Sugar
+open BNF_GFP_Rec_Sugar
+open BNF_GFP_Util
+open BNF_GFP_Grec
+open BNF_GFP_Grec_Sugar_Util
+open BNF_GFP_Grec_Sugar_Tactics
+
+val cong_N = "cong_";
+val baseN = "base";
+val reflN = "refl";
+val symN = "sym";
+val transN = "trans";
+val cong_introsN = prefix cong_N "intros";
+val cong_intros_friendN = "cong_intros_friend";
+val codeN = "code";
+val coinductN = "coinduct";
+val coinduct_uptoN = "coinduct_upto";
+val corecN = "corec";
+val ctrN = "ctr";
+val discN = "disc";
+val disc_iffN = "disc_iff";
+val eq_algrhoN = "eq_algrho";
+val eq_corecUUN = "eq_corecUU";
+val friendN = "friend";
+val inner_elimN = "inner_elim";
+val inner_inductN = "inner_induct";
+val inner_simpN = "inner_simp";
+val rhoN = "rho";
+val selN = "sel";
+val uniqueN = "unique";
+
+val inner_fp_suffix = "_inner_fp";
+
+val nitpicksimp_attrs = @{attributes [nitpick_simp]};
+val simp_attrs = @{attributes [simp]};
+val transfer_rule_attrs = @{attributes [transfer_rule]};
+
+val unfold_id_thms1 =
+  map (fn thm => thm RS eq_reflection) @{thms id_bnf_o o_id_bnf id_apply o_apply} @
+  @{thms fst_def[abs_def, symmetric] snd_def[abs_def, symmetric]};
+
+fun unfold_id_bnf_etc lthy =
+  let val thy = Proof_Context.theory_of lthy in
+    Raw_Simplifier.rewrite_term thy unfold_id_thms1 []
+    #> Raw_Simplifier.rewrite_term thy @{thms BNF_Composition.id_bnf_def} []
+  end;
+
+fun unexpected_corec_call ctxt eqns t =
+  error_at ctxt eqns ("Unexpected corecursive call in " ^ quote (Syntax.string_of_term ctxt t));
+fun unsupported_case_around_corec_call ctxt eqns t =
+  error_at ctxt eqns ("Unsupported corecursive call under case expression " ^
+    quote (Syntax.string_of_term ctxt t) ^ "\n(Define " ^
+    quote (Syntax.string_of_typ ctxt (domain_type (fastype_of t))) ^
+    " with  discriminators and selectors to circumvent this limitation.)");
+
+datatype corec_option =
+  Plugins_Option of Proof.context -> Plugin_Name.filter |
+  Friend_Option |
+  Transfer_Option;
+
+val corec_option_parser = Parse.group (K "option")
+  (Plugin_Name.parse_filter >> Plugins_Option
+   || Parse.reserved "friend" >> K Friend_Option
+   || Parse.reserved "transfer" >> K Transfer_Option);
+
+type codatatype_extra =
+  {case_dtor: thm,
+   case_trivial: thm,
+   abs_rep_transfers: thm list};
+
+fun morph_codatatype_extra phi ({case_dtor, case_trivial, abs_rep_transfers} : codatatype_extra) =
+  {case_dtor = Morphism.thm phi case_dtor, case_trivial = Morphism.thm phi case_trivial,
+   abs_rep_transfers = map (Morphism.thm phi) abs_rep_transfers};
+
+val transfer_codatatype_extra = morph_codatatype_extra o Morphism.transfer_morphism;
+
+type coinduct_extra =
+  {coinduct: thm,
+   coinduct_attrs: Token.src list,
+   cong_intro_tab: thm list Symtab.table};
+
+fun morph_coinduct_extra phi ({coinduct, coinduct_attrs, cong_intro_tab} : coinduct_extra) =
+  {coinduct = Morphism.thm phi coinduct, coinduct_attrs = coinduct_attrs,
+   cong_intro_tab = Symtab.map (K (Morphism.fact phi)) cong_intro_tab};
+
+val transfer_coinduct_extra = morph_coinduct_extra o Morphism.transfer_morphism;
+
+type friend_extra =
+  {eq_algrhos: thm list,
+   algrho_eqs: thm list};
+
+val empty_friend_extra = {eq_algrhos = [], algrho_eqs = []};
+
+fun merge_friend_extras ({eq_algrhos = eq_algrhos1, algrho_eqs = algrho_eqs1},
+    {eq_algrhos = eq_algrhos2, algrho_eqs = algrho_eqs2}) =
+  {eq_algrhos = union Thm.eq_thm_prop eq_algrhos1 eq_algrhos2,
+   algrho_eqs = union Thm.eq_thm_prop algrho_eqs1 algrho_eqs2};
+
+type corec_sugar_data =
+  codatatype_extra Symtab.table * coinduct_extra Symtab.table * friend_extra Symtab.table;
+
+structure Data = Generic_Data
+(
+  type T = corec_sugar_data;
+  val empty = (Symtab.empty, Symtab.empty, Symtab.empty);
+  val extend = I;
+  fun merge data : T =
+    (Symtab.merge (K true) (apply2 #1 data), Symtab.merge (K true) (apply2 #2 data),
+     Symtab.join (K merge_friend_extras) (apply2 #3 data));
+);
+
+fun register_codatatype_extra fpT_name extra =
+  Local_Theory.declaration {syntax = false, pervasive = true} (fn phi =>
+    Data.map (@{apply 3(1)} (Symtab.update (fpT_name, morph_codatatype_extra phi extra))));
+
+fun codatatype_extra_of ctxt =
+  Symtab.lookup (#1 (Data.get (Context.Proof ctxt)))
+  #> Option.map (transfer_codatatype_extra (Proof_Context.theory_of ctxt));
+
+fun all_codatatype_extras_of ctxt =
+  Symtab.dest (#1 (Data.get (Context.Proof ctxt)));
+
+fun register_coinduct_extra fpT_name extra =
+  Local_Theory.declaration {syntax = false, pervasive = true} (fn phi =>
+    Data.map (@{apply 3(2)} (Symtab.update (fpT_name, morph_coinduct_extra phi extra))));
+
+fun coinduct_extra_of ctxt =
+  Symtab.lookup (#2 (Data.get (Context.Proof ctxt)))
+  #> Option.map (transfer_coinduct_extra (Proof_Context.theory_of ctxt));
+
+fun register_friend_extra fun_name eq_algrho algrho_eq =
+  Local_Theory.declaration {syntax = false, pervasive = true} (fn phi =>
+    Data.map (@{apply 3(3)} (Symtab.map_default (fun_name, empty_friend_extra)
+      (fn {eq_algrhos, algrho_eqs} =>
+        {eq_algrhos = Morphism.thm phi eq_algrho :: eq_algrhos,
+         algrho_eqs = Morphism.thm phi algrho_eq :: algrho_eqs}))));
+
+fun all_friend_extras_of ctxt =
+  Symtab.dest (#3 (Data.get (Context.Proof ctxt)));
+
+fun coinduct_extras_of_generic context =
+  corec_infos_of_generic context
+  #> map (#corecUU #> dest_Const #> fst #> Symtab.lookup (#2 (Data.get context)) #> the
+    #> transfer_coinduct_extra (Context.theory_of context));
+
+fun get_coinduct_uptos fpT_name context =
+  coinduct_extras_of_generic context fpT_name |> map #coinduct;
+fun get_cong_all_intros fpT_name context =
+  coinduct_extras_of_generic context fpT_name |> maps (#cong_intro_tab #> Symtab.dest #> maps snd);
+fun get_cong_intros fpT_name name context =
+  coinduct_extras_of_generic context fpT_name
+  |> maps (#cong_intro_tab #> (fn tab => Symtab.lookup_list tab name));
+
+fun ctr_names_of_fp_name lthy fpT_name =
+  fpT_name |> fp_sugar_of lthy |> the |> #fp_ctr_sugar |> #ctr_sugar |> #ctrs
+  |> map (Long_Name.base_name o name_of_ctr);
+
+fun register_coinduct_dynamic_base fpT_name lthy =
+  let val fp_b = Binding.name (Long_Name.base_name fpT_name) in
+    lthy
+    |> fold Local_Theory.add_thms_dynamic
+      ((mk_fp_binding fp_b coinduct_uptoN, get_coinduct_uptos fpT_name) ::
+        map (fn N =>
+          let val N = cong_N ^ N in
+            (mk_fp_binding fp_b N, get_cong_intros fpT_name N)
+          end)
+        ([baseN, reflN, symN, transN] @ ctr_names_of_fp_name lthy fpT_name))
+    |> Local_Theory.add_thms_dynamic
+      (mk_fp_binding fp_b cong_introsN, get_cong_all_intros fpT_name)
+  end;
+
+fun register_coinduct_dynamic_friend fpT_name friend_name =
+  let
+    val fp_b = Binding.name (Long_Name.base_name fpT_name);
+    val friend_base_name = cong_N ^ Long_Name.base_name friend_name;
+  in
+    Local_Theory.add_thms_dynamic
+      (mk_fp_binding fp_b friend_base_name, get_cong_intros fpT_name friend_base_name)
+  end;
+
+fun derive_case_dtor ctxt fpT_name =
+  let
+    val thy = Proof_Context.theory_of ctxt;
+
+    val SOME ({fp_res_index, fp_res = {dtors, dtor_ctors, ...},
+        absT_info = {rep = rep0, abs_inverse, ...},
+        fp_ctr_sugar = {ctr_defs, ctr_sugar = {casex, exhaust, case_thms, ...}, ...}, ...}) =
+      fp_sugar_of ctxt fpT_name;
+
+    val (f_Ts, Type (_, [fpT, _])) = strip_fun_type (fastype_of casex);
+    val x_Tss = map binder_types f_Ts;
+
+    val (((u, fs), xss), _) = ctxt
+      |> yield_singleton (mk_Frees "y") fpT
+      ||>> mk_Frees "f" f_Ts
+      ||>> mk_Freess "x" x_Tss;
+
+    val dtor = nth dtors fp_res_index;
+    val u' = dtor $ u;
+
+    val absT = fastype_of u';
+
+    val rep = mk_rep absT rep0;
+
+    val goal = mk_Trueprop_eq (list_comb (casex, fs) $ u,
+        mk_case_absumprod absT rep fs xss xss $ u')
+      |> Raw_Simplifier.rewrite_term thy @{thms comp_def[THEN eq_reflection]} [];
+    val vars = map (fst o dest_Free) (u :: fs);
+
+    val dtor_ctor = nth dtor_ctors fp_res_index;
+  in
+    Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_case_dtor_tac ctxt u abs_inverse dtor_ctor ctr_defs exhaust case_thms)
+    |> Thm.close_derivation
+  end;
+
+fun derive_case_trivial ctxt fpT_name =
+  let
+    val SOME {casex, exhaust, case_thms, ...} = ctr_sugar_of ctxt fpT_name;
+
+    val fpT0 as Type (_, As0) = domain_type (body_fun_type (fastype_of casex));
+
+    val (As, _) = ctxt
+      |> mk_TFrees (length As0);
+    val fpT = Type (fpT_name, As);
+
+    val (var_name, ()) = singleton (Variable.variant_frees ctxt []) ("x", ());
+    val var = Free (var_name, fpT);
+    val goal = mk_Trueprop_eq (expand_to_ctr_term ctxt fpT var, var);
+
+    val exhaust' = Drule.infer_instantiate' ctxt [SOME (Thm.cterm_of ctxt var)] exhaust;
+  in
+    Goal.prove_sorry ctxt [var_name] [] goal (fn {context = ctxt, prems = _} =>
+      HEADGOAL (rtac ctxt exhaust') THEN ALLGOALS (hyp_subst_tac ctxt) THEN
+      unfold_thms_tac ctxt case_thms THEN ALLGOALS (rtac ctxt refl))
+    |> Thm.close_derivation
+  end;
+
+fun mk_abs_rep_transfers ctxt fpT_name =
+  [mk_abs_transfer ctxt fpT_name, mk_rep_transfer ctxt fpT_name]
+  handle Fail _ => [];
+
+fun set_transfer_rule_attrs thms =
+  snd o Local_Theory.notes [((Binding.empty, []), [(thms, transfer_rule_attrs)])];
+
+fun ensure_codatatype_extra fpT_name ctxt =
+  (case codatatype_extra_of ctxt fpT_name of
+    NONE =>
+    let val abs_rep_transfers = mk_abs_rep_transfers ctxt fpT_name in
+      ctxt
+      |> register_codatatype_extra fpT_name
+        {case_dtor = derive_case_dtor ctxt fpT_name,
+         case_trivial = derive_case_trivial ctxt fpT_name,
+         abs_rep_transfers = abs_rep_transfers}
+      |> set_transfer_rule_attrs abs_rep_transfers
+    end
+  | SOME {abs_rep_transfers, ...} => ctxt |> set_transfer_rule_attrs abs_rep_transfers);
+
+fun setup_base fpT_name =
+  register_coinduct_dynamic_base fpT_name
+  #> ensure_codatatype_extra fpT_name;
+
+(*TODO: Merge with primcorec "case_of"*)
+fun case_of ctxt fcT_name =
+  (case ctr_sugar_of ctxt fcT_name of
+    SOME {casex = Const (s, _), ...} => SOME s
+  | _ => NONE);
+
+fun is_set ctxt (const_name, T) =
+  (case T of
+    Type (@{type_name fun}, [Type (fpT_name, _), Type (@{type_name set}, [_])]) =>
+    (case bnf_of ctxt fpT_name of
+      SOME bnf => exists (fn Const (s, _) => s = const_name | _ => false) (sets_of_bnf bnf)
+    | NONE => false)
+  | _ => false);
+
+fun case_eq_if_thms_of_term ctxt t =
+  let val ctr_sugars = map_filter (ctr_sugar_of_case ctxt o fst) (Term.add_consts t []) in
+    maps #case_eq_ifs ctr_sugars
+  end;
+
+fun all_algrho_eqs_of ctxt =
+  maps (#algrho_eqs o snd) (all_friend_extras_of ctxt);
+
+fun derive_code ctxt inner_fp_simps goal
+    {sig_fp_sugars, ssig_fp_sugar, eval, eval_simps, all_algLam_algs, corecUU_thm, ...} res_T fun_t
+    fun_def =
+  let
+    val fun_T = fastype_of fun_t;
+    val (arg_Ts, Type (fpT_name, _)) = strip_type fun_T;
+    val num_args = length arg_Ts;
+
+    val SOME {pre_bnf, fp_bnf, absT_info, fp_nesting_bnfs, live_nesting_bnfs, fp_ctr_sugar, ...} =
+      fp_sugar_of ctxt fpT_name;
+    val SOME {case_trivial, ...} = codatatype_extra_of ctxt fpT_name;
+
+    val ctr_sugar = #ctr_sugar fp_ctr_sugar;
+    val pre_map_def = map_def_of_bnf pre_bnf;
+    val abs_inverse = #abs_inverse absT_info;
+    val ctr_defs = #ctr_defs fp_ctr_sugar;
+    val case_eq_ifs = #case_eq_ifs ctr_sugar @ case_eq_if_thms_of_term ctxt goal;
+    val all_sig_map_thms = maps (#map_thms o #fp_bnf_sugar) sig_fp_sugars;
+
+    val fp_map_ident = map_ident_of_bnf fp_bnf;
+    val fpsig_nesting_bnfs = fp_nesting_bnfs @ maps #live_nesting_bnfs sig_fp_sugars;
+    val fpsig_nesting_T_names = map (fst o dest_Type o T_of_bnf) fpsig_nesting_bnfs;
+    val fpsig_nesting_fp_sugars = map_filter (fp_sugar_of ctxt) fpsig_nesting_T_names;
+    val fpsig_nesting_fp_bnf_sugars = map #fp_bnf_sugar fpsig_nesting_fp_sugars;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+    val ssig_map = map_of_bnf ssig_bnf;
+    val fpsig_nesting_maps = map map_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_ident0s = map map_ident0_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_comps = map map_comp_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_thms = maps #map_thms fpsig_nesting_fp_bnf_sugars;
+    val live_nesting_map_ident0s = map map_ident0_of_bnf live_nesting_bnfs;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val all_algLam_alg_pointfuls = map (mk_pointful ctxt) all_algLam_algs;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_code_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+        fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+        live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs corecUU_thm
+        all_sig_map_thms ssig_map_thms all_algLam_alg_pointfuls (all_algrho_eqs_of ctxt) eval_simps
+        inner_fp_simps fun_def))
+    |> Thm.close_derivation
+  end;
+
+fun derive_unique ctxt phi code_goal
+    {sig_fp_sugars, ssig_fp_sugar, eval, eval_simps, all_algLam_algs, corecUU_unique, ...}
+    (res_T as Type (fpT_name, _)) eq_corecUU =
+  let
+    val SOME {pre_bnf, fp_bnf, absT_info, fp_nesting_bnfs, live_nesting_bnfs, fp_ctr_sugar, ...} =
+      fp_sugar_of ctxt fpT_name;
+    val SOME {case_trivial, ...} = codatatype_extra_of ctxt fpT_name;
+
+    val ctr_sugar = #ctr_sugar fp_ctr_sugar;
+    val pre_map_def = map_def_of_bnf pre_bnf;
+    val abs_inverse = #abs_inverse absT_info;
+    val ctr_defs = #ctr_defs fp_ctr_sugar;
+    val case_eq_ifs = #case_eq_ifs ctr_sugar @ case_eq_if_thms_of_term ctxt code_goal;
+    val all_sig_map_thms = maps (#map_thms o #fp_bnf_sugar) sig_fp_sugars;
+
+    val fp_map_ident = map_ident_of_bnf fp_bnf;
+    val fpsig_nesting_bnfs = fp_nesting_bnfs @ maps #live_nesting_bnfs sig_fp_sugars;
+    val fpsig_nesting_T_names = map (fst o dest_Type o T_of_bnf) fpsig_nesting_bnfs;
+    val fpsig_nesting_fp_sugars = map_filter (fp_sugar_of ctxt) fpsig_nesting_T_names;
+    val fpsig_nesting_fp_bnf_sugars = map #fp_bnf_sugar fpsig_nesting_fp_sugars;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+    val ssig_map = map_of_bnf ssig_bnf;
+    val fpsig_nesting_maps = map map_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_ident0s = map map_ident0_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_comps = map map_comp_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_thms = maps #map_thms fpsig_nesting_fp_bnf_sugars;
+    val live_nesting_map_ident0s = map map_ident0_of_bnf live_nesting_bnfs;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val all_algLam_alg_pointfuls = map (mk_pointful ctxt) all_algLam_algs;
+
+    val @{const Trueprop} $ (Const (@{const_name HOL.eq}, _) $ lhs $ rhs) = code_goal;
+    val (fun_t, args) = strip_comb lhs;
+    val closed_rhs = fold_rev lambda args rhs;
+
+    val fun_T = fastype_of fun_t;
+    val num_args = num_binder_types fun_T;
+
+    val f = Free (singleton (Variable.variant_frees ctxt []) ("f", fun_T));
+
+    val is_self_call = curry (op aconv) fun_t;
+    val has_self_call = exists_subterm is_self_call;
+
+    fun fify args (t $ u) = fify (u :: args) t $ fify [] u
+      | fify _ (Abs (s, T, t)) = Abs (s, T, fify [] t)
+      | fify args t = if t = fun_t andalso not (exists has_self_call args) then f else t;
+
+    val goal = Logic.mk_implies (mk_Trueprop_eq (f, fify [] closed_rhs), mk_Trueprop_eq (f, fun_t))
+      |> Morphism.term phi;
+  in
+    Goal.prove_sorry ctxt [fst (dest_Free f)] [] goal (fn {context = ctxt, prems = _} =>
+      mk_unique_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+        fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+        live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs all_sig_map_thms
+        ssig_map_thms all_algLam_alg_pointfuls (all_algrho_eqs_of ctxt) eval_simps corecUU_unique
+        eq_corecUU)
+    |> Thm.close_derivation
+  end;
+
+fun derive_last_disc ctxt fcT_name =
+  let
+    val SOME {T = fcT, discs, exhaust, disc_thmss, ...} = ctr_sugar_of ctxt fcT_name;
+
+    val (u, _) = ctxt
+      |> yield_singleton (mk_Frees "x") fcT;
+
+    val udiscs = map (rapp u) discs;
+    val (not_udiscs, last_udisc) = split_last udiscs
+      |>> map HOLogic.mk_not;
+
+    val goal = mk_Trueprop_eq (last_udisc, foldr1 HOLogic.mk_conj not_udiscs);
+  in
+    Goal.prove_sorry ctxt [fst (dest_Free u)] [] goal (fn {context = ctxt, prems = _} =>
+      mk_last_disc_tac ctxt u exhaust (flat disc_thmss))
+    |> Thm.close_derivation
+  end;
+
+fun derive_eq_algrho ctxt {sig_fp_sugars, ssig_fp_sugar, eval, eval_simps, all_algLam_algs,
+      corecUU_unique, ...}
+    ({algrho = algrho0, dtor_algrho, ...} : friend_info) fun_t k_T code_goal const_transfers rho_def
+    eq_corecUU =
+  let
+    val fun_T = fastype_of fun_t;
+    val (arg_Ts, Type (fpT_name, Ts)) = strip_type fun_T;
+    val num_args = length arg_Ts;
+
+    val SOME {fp_res_index, fp_res, pre_bnf, fp_bnf, absT_info, fp_nesting_bnfs, live_nesting_bnfs,
+        fp_ctr_sugar, ...} =
+      fp_sugar_of ctxt fpT_name;
+    val SOME {case_dtor, ...} = codatatype_extra_of ctxt fpT_name;
+
+    val fp_nesting_Ts = map T_of_bnf fp_nesting_bnfs;
+
+    fun is_nullary_disc_def (@{const Trueprop} $ (Const (@{const_name HOL.eq}, _) $ _
+          $ (Const (@{const_name HOL.eq}, _) $ _ $ _))) = true
+      | is_nullary_disc_def (Const (@{const_name Pure.eq}, _) $ _
+          $ (Const (@{const_name HOL.eq}, _) $ _ $ _)) = true
+      | is_nullary_disc_def _ = false;
+
+    val dtor_ctor = nth (#dtor_ctors fp_res) fp_res_index;
+    val ctor_iff_dtor = #ctor_iff_dtor fp_ctr_sugar;
+    val ctr_sugar = #ctr_sugar fp_ctr_sugar;
+    val pre_map_def = map_def_of_bnf pre_bnf;
+    val abs_inverse = #abs_inverse absT_info;
+    val ctr_defs = #ctr_defs fp_ctr_sugar;
+    val nullary_disc_defs = filter (is_nullary_disc_def o Thm.prop_of) (#disc_defs ctr_sugar);
+    val disc_sel_eq_cases = #disc_eq_cases ctr_sugar @ #sel_defs ctr_sugar;
+    val case_eq_ifs = #case_eq_ifs ctr_sugar @ case_eq_if_thms_of_term ctxt code_goal;
+    val all_sig_map_thms = maps (#map_thms o #fp_bnf_sugar) sig_fp_sugars;
+
+    fun add_tnameT (Type (s, Ts)) = insert (op =) s #> fold add_tnameT Ts
+      | add_tnameT _ = I;
+
+    fun map_disc_sels'_of s =
+      (case fp_sugar_of ctxt s of
+        SOME {fp_bnf_sugar = {map_disc_iffs, map_selss, ...}, ...} =>
+        let
+          val map_selss' =
+            if length map_selss <= 1 then map_selss
+            else map (map (unfold_thms ctxt (no_refl [derive_last_disc ctxt s]))) map_selss;
+        in
+          map_disc_iffs @ flat map_selss'
+        end
+      | NONE => []);
+
+    fun mk_const_pointful_natural const_transfer =
+      SOME (mk_pointful_natural_from_transfer ctxt const_transfer)
+      handle UNNATURAL () => NONE;
+
+    val const_pointful_natural_opts = map mk_const_pointful_natural const_transfers;
+    val const_pointful_naturals = map_filter I const_pointful_natural_opts;
+    val fp_nesting_k_T_names = fold add_tnameT (k_T :: fp_nesting_Ts) [];
+    val fp_nesting_k_map_disc_sels' = maps map_disc_sels'_of fp_nesting_k_T_names;
+
+    val fp_map_ident = map_ident_of_bnf fp_bnf;
+    val fpsig_nesting_bnfs = fp_nesting_bnfs @ maps #live_nesting_bnfs sig_fp_sugars;
+    val fpsig_nesting_T_names = map (fst o dest_Type o T_of_bnf) fpsig_nesting_bnfs;
+    val fpsig_nesting_fp_sugars = map_filter (fp_sugar_of ctxt) fpsig_nesting_T_names;
+    val fpsig_nesting_fp_bnf_sugars = map #fp_bnf_sugar fpsig_nesting_fp_sugars;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+    val ssig_map = map_of_bnf ssig_bnf;
+    val fpsig_nesting_maps = map map_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_ident0s = map map_ident0_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_comps = map map_comp_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_thms = maps #map_thms fpsig_nesting_fp_bnf_sugars;
+    val live_nesting_map_ident0s = map map_ident0_of_bnf live_nesting_bnfs;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val all_algLam_alg_pointfuls = map (mk_pointful ctxt) all_algLam_algs;
+
+    val ctor = nth (#ctors fp_res) fp_res_index;
+    val abs = #abs absT_info;
+    val rep = #rep absT_info;
+    val algrho = mk_ctr Ts algrho0;
+
+    val goal = mk_Trueprop_eq (fun_t, abs_curried_balanced arg_Ts algrho);
+
+    fun const_of_transfer thm =
+      (case Thm.prop_of thm of @{const Trueprop} $ (_ $ cst $ _) => cst);
+
+    val eq_algrho =
+      Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt [] [] goal (fn {context = ctxt, prems = _} =>
+        mk_eq_algrho_tac ctxt fpsig_nesting_maps abs rep ctor ssig_map eval pre_map_def abs_inverse
+          fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+          live_nesting_map_ident0s fp_map_ident dtor_ctor ctor_iff_dtor ctr_defs nullary_disc_defs
+          disc_sel_eq_cases case_dtor case_eq_ifs const_pointful_naturals
+          fp_nesting_k_map_disc_sels' rho_def dtor_algrho corecUU_unique eq_corecUU all_sig_map_thms
+          ssig_map_thms all_algLam_alg_pointfuls (all_algrho_eqs_of ctxt) eval_simps)
+      |> Thm.close_derivation
+      handle e as ERROR _ =>
+        (case filter (is_none o snd) (const_transfers ~~ const_pointful_natural_opts) of
+          [] => Exn.reraise e
+        | thm_nones =>
+          error ("Failed to state naturality property for " ^
+            commas (map (Syntax.string_of_term ctxt o const_of_transfer o fst) thm_nones)));
+
+    val algrho_eq = eq_algrho RS (mk_curry_uncurryN_balanced ctxt num_args RS iffD2) RS sym;
+  in
+    (eq_algrho, algrho_eq)
+  end;
+
+fun prime_rho_transfer_goal ctxt fpT_name rho_def goal =
+  let
+    val thy = Proof_Context.theory_of ctxt;
+
+    val SOME {pre_bnf, ...} = fp_sugar_of ctxt fpT_name;
+    val SOME {abs_rep_transfers, ...} = codatatype_extra_of ctxt fpT_name;
+
+    val simps = rel_def_of_bnf pre_bnf :: rho_transfer_simps;
+    val fold_rho = unfold_thms ctxt [rho_def RS @{thm symmetric}];
+
+    fun derive_unprimed rho_transfer' =
+      Variable.add_free_names ctxt goal []
+      |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+        unfold_thms_tac ctxt simps THEN HEADGOAL (rtac ctxt rho_transfer')))
+      |> Thm.close_derivation;
+
+    val goal' = Raw_Simplifier.rewrite_term thy simps [] goal;
+  in
+    if null abs_rep_transfers then (goal', derive_unprimed #> fold_rho)
+    else (goal, fold_rho)
+  end;
+
+fun derive_rho_transfer_folded ctxt fpT_name const_transfers rho_def goal =
+  let
+    val SOME {pre_bnf, ...} = fp_sugar_of ctxt fpT_name;
+    val SOME {abs_rep_transfers, ...} = codatatype_extra_of ctxt fpT_name;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_rho_transfer_tac ctxt (null abs_rep_transfers) (rel_def_of_bnf pre_bnf)
+      const_transfers))
+    |> unfold_thms ctxt [rho_def RS @{thm symmetric}]
+    |> Thm.close_derivation
+  end;
+
+fun mk_cong_intro_ctr_or_friend_goal ctxt fpT Rcong alg =
+  let
+    val xy_Ts = binder_types (fastype_of alg);
+
+    val ((xs, ys), _) = ctxt
+      |> mk_Frees "x" xy_Ts
+      ||>> mk_Frees "y" xy_Ts;
+
+    fun mk_prem xy_T x y =
+      BNF_Def.build_rel [] ctxt [fpT]
+        (fn (T, _) => if T = fpT then Rcong else HOLogic.eq_const T) (xy_T, xy_T) $ x $ y;
+
+    val prems = @{map 3} mk_prem xy_Ts xs ys;
+    val concl = Rcong $ list_comb (alg, xs) $ list_comb (alg, ys);
+  in
+    Logic.list_implies (map HOLogic.mk_Trueprop prems, HOLogic.mk_Trueprop concl)
+  end;
+
+fun derive_cong_ctr_intros ctxt cong_ctor_intro =
+  let
+    val @{const Pure.imp} $ _ $ (@{const Trueprop} $ ((Rcong as _ $ _) $ _ $ (ctor $ _))) =
+      Thm.prop_of cong_ctor_intro;
+
+    val fpT as Type (fpT_name, fp_argTs) = range_type (fastype_of ctor);
+
+    val SOME {pre_bnf, absT_info = {abs_inverse, ...},
+        fp_ctr_sugar = {ctr_defs, ctr_sugar = {ctrs = ctrs0, ...}, ...}, ...} =
+      fp_sugar_of ctxt fpT_name;
+
+    val ctrs = map (mk_ctr fp_argTs) ctrs0;
+    val pre_rel_def = rel_def_of_bnf pre_bnf;
+
+    fun prove ctr_def goal =
+      Variable.add_free_names ctxt goal []
+      |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+        mk_cong_intro_ctr_or_friend_tac ctxt ctr_def [pre_rel_def, abs_inverse] cong_ctor_intro))
+      |> Thm.close_derivation;
+
+    val goals = map (mk_cong_intro_ctr_or_friend_goal ctxt fpT Rcong) ctrs;
+  in
+    map2 prove ctr_defs goals
+  end;
+
+fun derive_cong_friend_intro ctxt cong_algrho_intro =
+  let
+    val @{const Pure.imp} $ _ $ (@{const Trueprop} $ ((Rcong as _ $ _) $ _
+        $ ((algrho as Const (algrho_name, _)) $ _))) =
+      Thm.prop_of cong_algrho_intro;
+
+    val fpT as Type (_, fp_argTs) = range_type (fastype_of algrho);
+
+    fun has_algrho (@{const Trueprop} $ (Const (@{const_name HOL.eq}, _) $ _ $ rhs)) =
+      fst (dest_Const (head_of (strip_abs_body rhs))) = algrho_name;
+
+    val eq_algrho :: _ =
+      maps (filter (has_algrho o Thm.prop_of) o #eq_algrhos o snd) (all_friend_extras_of ctxt);
+
+    val @{const Trueprop} $ (Const (@{const_name HOL.eq}, _) $ friend0 $ _) = Thm.prop_of eq_algrho;
+    val friend = mk_ctr fp_argTs friend0;
+
+    val goal = mk_cong_intro_ctr_or_friend_goal ctxt fpT Rcong friend;
+  in
+    Variable.add_free_names ctxt goal []
+    |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_cong_intro_ctr_or_friend_tac ctxt eq_algrho [] cong_algrho_intro))
+    |> Thm.close_derivation
+  end;
+
+fun derive_cong_intros lthy ctr_names friend_names
+    ({cong_base, cong_refl, cong_sym, cong_trans, cong_alg_intros, ...} : dtor_coinduct_info) =
+  let
+    val cong_ctor_intro :: cong_algrho_intros = rev cong_alg_intros;
+    val names = map (prefix cong_N) ([baseN, reflN, symN, transN] @ ctr_names @ friend_names);
+    val thms = [cong_base, cong_refl, cong_sym, cong_trans] @
+      derive_cong_ctr_intros lthy cong_ctor_intro @
+      map (derive_cong_friend_intro lthy) cong_algrho_intros;
+  in
+    Symtab.make_list (names ~~ thms)
+  end;
+
+fun derive_coinduct ctxt (fpT as Type (fpT_name, _)) dtor_coinduct =
+  let
+    val thy = Proof_Context.theory_of ctxt;
+
+    val @{const Pure.imp} $ (@{const Trueprop} $ (_ $ Abs (_, _, _ $
+        Abs (_, _, @{const implies} $ _ $ (_ $ (cong0 $ _) $ _ $ _))))) $ _ =
+      Thm.prop_of dtor_coinduct;
+
+    val SOME {X as TVar ((X_s, _), _), fp_res = {dtor_ctors, ...}, pre_bnf,
+        absT_info = {abs_inverse, ...}, live_nesting_bnfs,
+        fp_ctr_sugar = {ctrXs_Tss, ctr_defs,
+          ctr_sugar = ctr_sugar0 as {T = T0, ctrs = ctrs0, discs = discs0, ...}, ...}, ...} =
+      fp_sugar_of ctxt fpT_name;
+
+    val n = length ctrXs_Tss;
+    val ms = map length ctrXs_Tss;
+
+    val X' = TVar ((X_s, maxidx_of_typ fpT + 1), @{sort type});
+    val As_rho = tvar_subst thy [T0] [fpT];
+    val substXAT = Term.typ_subst_TVars As_rho o Tsubst X X';
+    val substXA = Term.subst_TVars As_rho o substT X X';
+    val phi = Morphism.typ_morphism "BNF" substXAT $> Morphism.term_morphism "BNF" substXA;
+
+    fun mk_applied_cong arg =
+      enforce_type ctxt domain_type (fastype_of arg) cong0 $ arg;
+
+    val thm = derive_coinduct_thms_for_types false mk_applied_cong [pre_bnf] dtor_coinduct
+        dtor_ctors live_nesting_bnfs [fpT] [substXAT X] [map (map substXAT) ctrXs_Tss] [n]
+        [abs_inverse] [abs_inverse] I [ctr_defs] [morph_ctr_sugar phi ctr_sugar0] ctxt
+      |> map snd |> the_single;
+    val (attrs, _) = mk_coinduct_attrs [fpT] [ctrs0] [discs0] [ms];
+  in
+    (thm, attrs)
+  end;
+
+type explore_parameters =
+  {bound_Us: typ list,
+   bound_Ts: typ list,
+   U: typ,
+   T: typ};
+
+fun update_UT {bound_Us, bound_Ts, ...} U T =
+  {bound_Us = bound_Us, bound_Ts = bound_Ts, U = U, T = T};
+
+fun explore_nested lthy explore {bound_Us, bound_Ts, U, T} t =
+  let
+    fun build_simple (T, U) =
+      if T = U then
+        @{term "%y. y"}
+      else
+        Bound 0
+        |> explore {bound_Us = T :: bound_Us, bound_Ts = T :: bound_Ts, U = U, T = T}
+        |> (fn t => Abs (Name.uu, T, t));
+  in
+    betapply (build_map lthy [] build_simple (T, U), t)
+  end;
+
+fun add_boundvar t = betapply (incr_boundvars 1 t, Bound 0);
+
+fun explore_fun (arg_U :: arg_Us) explore {bound_Us, bound_Ts, U, T} t =
+    let val arg_name = the_default Name.uu (try (fn (Abs (s, _, _)) => s) t) in
+      add_boundvar t
+      |> explore_fun arg_Us explore
+        {bound_Us = arg_U :: bound_Us, bound_Ts = domain_type T :: bound_Ts, U = range_type U,
+         T = range_type T}
+      |> (fn t => Abs (arg_name, arg_U, t))
+    end
+  | explore_fun [] explore params t = explore params t;
+
+fun massage_fun explore (params as {T, U, ...}) =
+  if can dest_funT T then explore_fun [domain_type U] explore params else explore params;
+
+fun massage_star massages explore =
+  let
+    fun after_massage massages' t params t' =
+      if t aconv t' then massage_any massages' params t else massage_any massages params t'
+    and massage_any [] params t = explore params t
+      | massage_any (massage :: massages') params t =
+        massage (after_massage massages' t) params t;
+  in
+    massage_any massages
+  end;
+
+fun massage_let explore params t =
+  (case strip_comb t of
+    (Const (@{const_name Let}, _), [_, _]) => unfold_lets_splits t
+  | _ => t)
+  |> explore params;
+
+fun check_corec_equation ctxt fun_frees (lhs, rhs) =
+  let
+    val (fun_t, arg_ts) = strip_comb lhs;
+
+    fun check_fun_name () =
+      null fun_frees orelse member (op aconv) fun_frees fun_t orelse
+      error (quote (Syntax.string_of_term ctxt fun_t) ^
+        " is not the function currently being defined");
+
+    fun check_args_are_vars () =
+      let
+        fun is_ok_Free_or_Var (Free (s, _)) = not (String.isSuffix inner_fp_suffix s)
+          | is_ok_Free_or_Var (Var _) = true
+          | is_ok_Free_or_Var _ = false;
+
+        fun is_valid arg =
+          (is_ok_Free_or_Var arg andalso not (member (op aconv) fun_frees arg)) orelse
+          error ("Argument " ^ quote (Syntax.string_of_term ctxt arg) ^ " is not free");
+      in
+        forall is_valid arg_ts
+      end;
+
+    fun check_no_duplicate_arg () =
+      (case duplicates (op =) arg_ts of
+        [] => ()
+      | arg :: _ => error ("Repeated argument: " ^ quote (Syntax.string_of_term ctxt arg)));
+
+    fun check_no_other_frees () =
+      let
+        val known_frees = fun_frees @ arg_ts;
+
+        fun check_free (t as Free (s, _)) =
+            Variable.is_fixed ctxt s orelse member (op aconv) known_frees t orelse
+            error ("Unexpected variable: " ^ quote s)
+          | check_free _ = false;
+      in
+        Term.exists_subterm check_free rhs
+      end;
+  in
+    check_no_duplicate_arg ();
+    check_fun_name ();
+    check_args_are_vars ();
+    check_no_other_frees ()
+  end;
+
+fun parse_corec_equation ctxt fun_frees eq =
+  let
+    val (lhs, rhs) = HOLogic.dest_eq (HOLogic.dest_Trueprop (drop_all eq))
+      handle TERM _ => error "Expected equation";
+
+    val _ = check_corec_equation ctxt fun_frees (lhs, rhs);
+
+    val (fun_t, arg_ts) = strip_comb lhs;
+    val (arg_Ts, _) = strip_type (fastype_of fun_t);
+    val added_Ts = drop (length arg_ts) arg_Ts;
+    val free_names = mk_names (length added_Ts) "x" ~~ added_Ts;
+    val free_args = Variable.variant_frees ctxt [rhs, lhs] free_names |> map Free;
+  in
+    (arg_ts @ free_args, list_comb (rhs, free_args))
+  end;
+
+fun morph_views phi (code, ctrs, discs, disc_iffs, sels) =
+  (Morphism.term phi code, map (Morphism.term phi) ctrs, map (Morphism.term phi) discs,
+   map (Morphism.term phi) disc_iffs, map (Morphism.term phi) sels);
+
+fun generate_views ctxt eq fun_t (lhs_free_args, rhs) =
+  let
+    val lhs = list_comb (fun_t, lhs_free_args);
+    val T as Type (T_name, Ts) = fastype_of rhs;
+    val SOME {fp_ctr_sugar = {ctr_sugar = {ctrs = ctrs0, discs = discs0, selss = selss0, ...}, ...},
+        ...} =
+      fp_sugar_of ctxt T_name;
+    val ctrs = map (mk_ctr Ts) ctrs0;
+    val discs = map (mk_disc_or_sel Ts) discs0;
+    val selss = map (map (mk_disc_or_sel Ts)) selss0;
+
+    val code_view = drop_all eq;
+
+    fun can_case_expand t = not (can (dest_ctr ctxt T_name) t);
+
+    fun generate_raw_views conds t raw_views =
+      let
+        fun analyse (ctr :: ctrs) (disc :: discs) ctr' =
+          if ctr = ctr' then
+            (conds, disc, ctr)
+          else
+            analyse ctrs discs ctr';
+      in
+        (analyse ctrs discs (fst (strip_comb t))) :: raw_views
+      end;
+
+    fun generate_disc_views raw_views =
+      if length discs = 1 then
+        ([], [])
+      else
+        let
+          fun collect_condss_disc condss [] _ = condss
+            | collect_condss_disc condss ((conds, disc', _) :: raw_views) disc =
+              collect_condss_disc (condss |> disc = disc' ? cons conds) raw_views disc;
+
+          val grouped_disc_views = discs
+            |> map (collect_condss_disc [] raw_views)
+            |> curry (op ~~) (map (fn disc => disc $ lhs) discs);
+
+          fun mk_disc_iff_props props [] = props
+            | mk_disc_iff_props _ ((lhs, @{const HOL.True}) :: _) = [lhs]
+            | mk_disc_iff_props props ((lhs, rhs) :: views) =
+              mk_disc_iff_props ((HOLogic.mk_eq (lhs, rhs)) :: props) views;
+        in
+          (grouped_disc_views
+           |> map swap,
+           grouped_disc_views
+           |> map (apsnd (s_dnf #> mk_conjs))
+           |> mk_disc_iff_props []
+           |> map (fn eq => ([[]], eq)))
+        end;
+
+    fun generate_ctr_views raw_views =
+      let
+        fun collect_condss_ctr condss [] _ = condss
+          | collect_condss_ctr condss ((conds, _, ctr') :: raw_views) ctr =
+            collect_condss_ctr (condss |> ctr = ctr' ? cons conds) raw_views ctr;
+
+        fun mk_ctr_eq ctr_sels ctr =
+          let
+            fun extract_arg n sel _(*bound_Ts*) fun_t arg_ts =
+              if ctr = fun_t then
+                nth arg_ts n
+              else
+                let val t = list_comb (fun_t, arg_ts) in
+                  if can_case_expand t then
+                    sel $ t
+                  else
+                    Term.dummy_pattern (range_type (fastype_of sel))
+                end;
+          in
+            ctr_sels
+            |> map_index (uncurry extract_arg)
+            |> map (fn extract => massage_corec_code_rhs ctxt extract [] rhs)
+            |> curry list_comb ctr
+            |> curry HOLogic.mk_eq lhs
+          end;
+
+          fun remove_condss_if_alone [(_, concl)] = [([[]], concl)]
+            | remove_condss_if_alone views = views;
+      in
+        ctrs
+        |> `(map (collect_condss_ctr [] raw_views))
+        ||> map2 mk_ctr_eq selss
+        |> op ~~
+        |> filter_out (null o fst)
+        |> remove_condss_if_alone
+      end;
+
+    fun generate_sel_views raw_views only_one_ctr =
+      let
+        fun mk_sel_positions sel =
+          let
+            fun get_sel_position _ [] = NONE
+              | get_sel_position i (sel' :: sels) =
+                if sel = sel' then SOME i else get_sel_position (i + 1) sels;
+          in
+            ctrs ~~ map (get_sel_position 0) selss
+            |> map_filter (fn (ctr, pos_opt) =>
+              if is_some pos_opt then SOME (ctr, the pos_opt) else NONE)
+          end;
+
+        fun collect_sel_condss0 condss [] _ = condss
+          | collect_sel_condss0 condss ((conds, _, ctr) :: raw_views) sel_positions =
+            let val condss' = condss |> is_some (AList.lookup (op =) sel_positions ctr) ? cons conds
+            in
+              collect_sel_condss0 condss' raw_views sel_positions
+            end;
+
+        val collect_sel_condss =
+          if only_one_ctr then K [[]] else collect_sel_condss0 [] raw_views;
+
+        fun mk_sel_rhs sel_positions sel =
+          let
+            val sel_T = range_type (fastype_of sel);
+
+            fun extract_sel_value _(*bound_Ts*) fun_t arg_ts =
+              (case AList.lookup (op =) sel_positions fun_t of
+                SOME n => nth arg_ts n
+              | NONE =>
+                let val t = list_comb (fun_t, arg_ts) in
+                  if can_case_expand t then
+                    sel $ t
+                  else
+                    Term.dummy_pattern sel_T
+                end);
+          in
+            massage_corec_code_rhs ctxt extract_sel_value [] rhs
+          end;
+
+        val ordered_sels = distinct (op =) (flat selss);
+        val sel_positionss = map mk_sel_positions ordered_sels;
+        val sel_rhss = map2 mk_sel_rhs sel_positionss ordered_sels;
+        val sel_lhss = map (rapp lhs o mk_disc_or_sel Ts) ordered_sels;
+        val sel_condss = map collect_sel_condss sel_positionss;
+
+        fun is_undefined (Const (@{const_name undefined}, _)) = true
+          | is_undefined _ = false;
+      in
+        sel_condss ~~ (sel_lhss ~~ sel_rhss)
+        |> filter_out (is_undefined o snd o snd)
+        |> map (apsnd HOLogic.mk_eq)
+      end;
+
+    fun mk_atomic_prop fun_args (condss, concl) =
+      (Logic.list_all (map dest_Free fun_args, abstract_over_list fun_args
+        (Logic.list_implies (map HOLogic.mk_Trueprop (s_dnf condss), HOLogic.mk_Trueprop concl))));
+
+    val raw_views = rhs
+      |> massage_let_if_case ctxt (K false) (fn _(*bound_Ts*) => fn t => t
+          |> can_case_expand t ? expand_to_ctr_term ctxt T) (K (K ())) (K I) []
+      |> (fn expanded_rhs => fold_rev_let_if_case ctxt generate_raw_views [] expanded_rhs [])
+      |> rev;
+    val (disc_views, disc_iff_views) = generate_disc_views raw_views;
+    val ctr_views = generate_ctr_views raw_views;
+    val sel_views = generate_sel_views raw_views (length ctr_views = 1);
+
+    val mk_props = filter_out (null o fst) #> map (mk_atomic_prop lhs_free_args);
+  in
+    (code_view, mk_props ctr_views, mk_props disc_views, mk_props disc_iff_views,
+     mk_props sel_views)
+  end;
+
+fun find_all_associated_types [] _ = []
+  | find_all_associated_types ((Type (_, Ts1), Type (_, Ts2)) :: TTs) T =
+    find_all_associated_types ((Ts1 ~~ Ts2) @ TTs) T
+  | find_all_associated_types ((T1, T2) :: TTs) T =
+    find_all_associated_types TTs T |> T1 = T ? cons T2;
+
+fun as_member_of tab = try dest_Const #> Option.mapPartial (fst #> Symtab.lookup tab);
+
+fun extract_rho_from_equation
+    ({ctr_guards, inner_buffer = {Oper, VLeaf, CLeaf, ctr_wrapper, friends}, ...},
+     {pattern_ctrs, discs, sels, it, mk_case})
+    b version Y preT ssig_T friend_tm (lhs_args, rhs) lthy =
+  let
+    val thy = Proof_Context.theory_of lthy;
+
+    val res_T = fastype_of rhs;
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+
+    fun fpT_to new_T T =
+      if T = res_T then
+        new_T
+      else
+        (case T of
+          Type (s, Ts) => Type (s, map (fpT_to new_T) Ts)
+        | _ => T);
+
+    fun build_params bound_Us bound_Ts T =
+      {bound_Us = bound_Us, bound_Ts = bound_Ts, U = T, T = T};
+
+    fun typ_before explore {bound_Us, bound_Ts, ...} t =
+      explore (build_params bound_Us bound_Ts (fastype_of1 (bound_Ts, t))) t;
+
+    val is_self_call = curry (op aconv) friend_tm;
+    val has_self_call = Term.exists_subterm is_self_call;
+
+    fun has_res_T bound_Ts t = fastype_of1 (bound_Ts, t) = res_T;
+
+    fun contains_res_T (Type (s, Ts)) = s = fst (dest_Type res_T) orelse exists contains_res_T Ts
+      | contains_res_T _ = false;
+
+    val is_lhs_arg = member (op =) lhs_args;
+
+    fun is_constant t =
+      not (Term.exists_subterm is_lhs_arg t orelse has_self_call t orelse loose_bvar (t, 0));
+    fun is_nested_type T = T <> res_T andalso T <> YpreT andalso T <> ssig_T;
+
+    val is_valid_case_argumentT = not o member (op =) [Y, ssig_T];
+
+    fun is_same_type_constr (Type (s, _)) (Type (s', _)) = (s = s')
+      | is_same_type_constr _ _ = false;
+
+    exception NO_ENCAPSULATION of unit;
+
+    val parametric_consts = Unsynchronized.ref [];
+
+    (* We are assuming that set functions are marked with "[transfer_rule]" (cf. the "transfer"
+       plugin). Otherwise, the "eq_algrho" tactic might fail. *)
+    fun is_special_parametric_const (x as (s, _)) =
+      s = @{const_name id} orelse is_set lthy x;
+
+    fun add_parametric_const s general_T T U =
+      let
+        fun tupleT_of_funT T =
+          let val (Ts, T) = strip_type T in
+            mk_tupleT_balanced (Ts @ [T])
+          end;
+
+        fun funT_of_tupleT n =
+          dest_tupleT_balanced (n + 1)
+          #> split_last
+          #> op --->;
+
+        val m = num_binder_types general_T;
+        val param1_T = Type_Infer.paramify_vars general_T;
+        val param2_T = Type_Infer.paramify_vars param1_T;
+
+        val deadfixed_T =
+          build_map lthy [] (mk_undefined o op -->) (apply2 tupleT_of_funT (param1_T, param2_T))
+          |> singleton (Type_Infer_Context.infer_types lthy)
+          |> singleton (Type_Infer.fixate lthy)
+          |> type_of
+          |> dest_funT
+          |-> BNF_GFP_Grec_Sugar_Util.generalize_types 1
+          |> funT_of_tupleT m;
+
+        val j = maxidx_of_typ deadfixed_T + 1;
+
+        fun varifyT (Type (s, Ts)) = Type (s, map varifyT Ts)
+          | varifyT (TFree (s, T)) = TVar ((s, j), T)
+          | varifyT T = T;
+
+        val dedvarified_T = varifyT deadfixed_T;
+
+        val new_vars = Sign.typ_match thy (dedvarified_T, T) Vartab.empty
+          |> Vartab.dest
+          |> filter (curry (op =) j o snd o fst)
+          |> Vartab.make;
+
+        val deadinstantiated_T = map_atyps (Type.devar new_vars) dedvarified_T;
+
+        val final_T =
+          if Sign.typ_instance thy (U, deadinstantiated_T) then deadfixed_T else general_T;
+      in
+        parametric_consts := insert (op =) (s, final_T) (!parametric_consts)
+      end;
+
+    fun encapsulate (params as {U, T, ...}) t =
+      if U = T then
+        t
+      else if T = Y then
+        VLeaf $ t
+      else if T = res_T then
+        CLeaf $ t
+      else if T = YpreT then
+        it $ t
+      else if is_nested_type T andalso is_same_type_constr T U then
+        explore_nested lthy encapsulate params t
+      else
+        raise NO_ENCAPSULATION ();
+
+    fun build_function_after_encapsulation fun_t fun_t' (params as {bound_Us, ...}) arg_ts arg_ts' =
+      let
+        val arg_Us' = fst (strip_typeN (length arg_ts) (fastype_of1 (bound_Us, fun_t')));
+
+        fun the_or_error arg NONE =
+            error ("Illegal argument " ^ quote (Syntax.string_of_term lthy arg) ^
+              " to " ^ quote (Syntax.string_of_term lthy fun_t))
+          | the_or_error _ (SOME arg') = arg';
+      in
+        arg_ts'
+        |> `(map (curry fastype_of1 bound_Us))
+        |>> map2 (update_UT params) arg_Us'
+        |> op ~~
+        |> map (try (uncurry encapsulate))
+        |> map2 the_or_error arg_ts
+        |> curry list_comb fun_t'
+      end;
+
+    fun rebuild_function_after_exploration old_fn new_fn explore params arg_ts =
+      arg_ts
+      |> map (typ_before explore params)
+      |> build_function_after_encapsulation old_fn new_fn params arg_ts;
+
+    fun update_case Us U casex =
+      let
+        val Type (T_name, _) = domain_type (snd (strip_fun_type (fastype_of casex)));
+        val SOME {fp_ctr_sugar = {ctr_sugar = {T = Type (_, Ts), casex, ...}, ...}, ...} =
+          fp_sugar_of lthy T_name;
+        val T = body_type (fastype_of casex);
+      in
+        Term.subst_atomic_types ((T :: Ts) ~~ (U :: Us)) casex
+      end;
+
+    fun deduce_according_type default_T [] = default_T
+      | deduce_according_type default_T Ts = (case distinct (op =) Ts of
+          U :: [] => U
+        | _ => fpT_to ssig_T default_T);
+
+    fun massage_if explore_cond explore (params as {bound_Us, bound_Ts, ...}) t =
+      (case strip_comb t of
+        (const as Const (@{const_name If}, _), obj :: (branches as [_, _])) =>
+        (case List.partition Term.is_dummy_pattern (map (explore params) branches) of
+          (dummy_branch' :: _, []) => dummy_branch'
+        | (_, [branch']) => branch'
+        | (_, branches') =>
+          let
+            val brancheUs = map (curry fastype_of1 bound_Us) branches';
+            val U = deduce_according_type (fastype_of1 (bound_Ts, hd branches)) brancheUs;
+            val const_obj' = (If_const U, obj)
+              ||> explore_cond (update_UT params @{typ bool} @{typ bool})
+              |> op $;
+          in
+            build_function_after_encapsulation (const $ obj) const_obj' params branches branches'
+          end)
+      | _ => explore params t);
+
+    fun massage_map explore (params as {bound_Us, bound_Ts, T = Type (T_name, Ts), ...})
+          (t as func $ mapped_arg) =
+        if is_self_call (head_of func) then
+          explore params t
+        else
+          (case try (dest_map lthy T_name) func of
+            SOME (map_tm, fs) =>
+            let
+              val n = length fs;
+              val mapped_arg' = mapped_arg
+                |> `(curry fastype_of1 bound_Ts)
+                |>> build_params bound_Us bound_Ts
+                |-> explore;
+              (* FIXME: This looks suspicious *)
+              val Us = map (fpT_to ssig_T) (snd (dest_Type (fastype_of1 (bound_Us, mapped_arg'))));
+              val temporary_map = map_tm
+                |> mk_map n Us Ts;
+              val map_fn_Ts = fastype_of #> strip_fun_type #> fst;
+              val binder_Uss = map_fn_Ts temporary_map
+                |> map (map (fpT_to ssig_T) o binder_types);
+              val fun_paramss = map_fn_Ts (head_of func)
+                |> map (build_params bound_Us bound_Ts);
+              val fs' = fs |> @{map 4} explore_fun binder_Uss (replicate n explore) fun_paramss;
+              val SOME bnf = bnf_of lthy T_name;
+              val Type (_, bnf_Ts) = T_of_bnf bnf;
+              val typ_alist =
+                lives_of_bnf bnf ~~ map (curry fastype_of1 bound_Us #> range_type) fs';
+              val Us' = map2 the_default Us (map (AList.lookup (op =) typ_alist) bnf_Ts);
+              val map_tm' = map_tm |> mk_map n Us Us';
+            in
+              build_function_after_encapsulation func (list_comb (map_tm', fs')) params [mapped_arg]
+                [mapped_arg']
+            end
+          | NONE => explore params t)
+      | massage_map explore params t = explore params t;
+
+    fun massage_comp explore (params as {bound_Us, ...}) t =
+      (case strip_comb t of
+        (Const (@{const_name comp}, _), f1 :: f2 :: args) =>
+        let
+          val args' = map (typ_before explore params) args;
+          val f2' = typ_before (explore_fun (map (curry fastype_of1 bound_Us) args') explore) params
+            f2;
+          val f1' = typ_before (explore_fun [range_type (fastype_of1 (bound_Us, f2'))] explore)
+            params f1;
+        in
+          betapply (f1', list_comb (f2', args'))
+        end
+      | _ => explore params t);
+
+    fun massage_ctr explore (params as {T = T as Type (s, Ts), bound_Us, ...}) t =
+        if T <> res_T then
+          (case try (dest_ctr lthy s) t of
+            SOME (ctr, args) =>
+            let
+              val args' = map (typ_before explore params) args;
+              val SOME {T = Type (_, ctr_Ts), ...} = ctr_sugar_of lthy s;
+              val temp_ctr = mk_ctr ctr_Ts ctr;
+              val argUs = map (curry fastype_of1 bound_Us) args';
+              val typ_alist = binder_types (fastype_of temp_ctr) ~~ argUs;
+              val Us = ctr_Ts
+                |> map (find_all_associated_types typ_alist)
+                |> map2 deduce_according_type Ts;
+              val ctr' = mk_ctr Us ctr;
+            in
+              build_function_after_encapsulation ctr ctr' params args args'
+            end
+          | NONE => explore params t)
+        else
+          explore params t
+      | massage_ctr explore params t = explore params t;
+
+    fun const_of [] _ = NONE
+      | const_of ((sel as Const (s1, _)) :: r) (const as Const (s2, _)) =
+        if s1 = s2 then SOME sel else const_of r const
+      | const_of _ _ = NONE;
+
+    fun massage_disc explore (params as {T, bound_Us, bound_Ts, ...}) t =
+      (case (strip_comb t, T = @{typ bool}) of
+        ((fun_t, arg :: []), true) =>
+        let val arg_T = fastype_of1 (bound_Ts, arg) in
+          if arg_T <> res_T then
+            (case arg_T |> try (fst o dest_Type) |> Option.mapPartial (ctr_sugar_of lthy) of
+              SOME {discs, T = Type (_, Ts), ...} =>
+              (case const_of discs fun_t of
+                SOME disc =>
+                let
+                  val arg' = arg |> typ_before explore params;
+                  val Type (_, Us) = fastype_of1 (bound_Us, arg');
+                  val disc' = disc |> Term.subst_TVars (map (fst o dest_TVar) Ts ~~ Us);
+                in
+                  disc' $ arg'
+                end
+              | NONE => explore params t)
+            | NONE => explore params t)
+          else
+            explore params t
+        end
+      | _ => explore params t);
+
+    fun massage_sel explore (params as {bound_Us, bound_Ts, ...}) t =
+      let val (fun_t, args) = strip_comb t in
+        if args = [] then
+          explore params t
+        else
+          let val T = fastype_of1 (bound_Ts, hd args) in
+            (case (Option.mapPartial (ctr_sugar_of lthy) (try (fst o dest_Type) T), T <> res_T) of
+              (SOME {selss, T = Type (_, Ts), ...}, true) =>
+              (case const_of (fold (curry op @) selss []) fun_t of
+                SOME sel =>
+                let
+                  val args' = args |> map (typ_before explore params);
+                  val Type (_, Us) = fastype_of1 (bound_Us, hd args');
+                  val sel' = sel |> Term.subst_TVars (map (fst o dest_TVar) Ts ~~ Us);
+                in
+                  build_function_after_encapsulation sel sel' params args args'
+                end
+              | NONE => explore params t)
+            | _ => explore params t)
+          end
+      end;
+
+    fun massage_equality explore (params as {bound_Us, bound_Ts, ...})
+          (t as Const (@{const_name HOL.eq}, _) $ t1 $ t2) =
+        let
+          val check_is_VLeaf =
+            not o (Term.exists_subterm (fn t => t aconv CLeaf orelse t aconv Oper));
+
+          fun try_pattern_matching (fun_t, arg_ts) t =
+            (case as_member_of pattern_ctrs fun_t of
+              SOME (disc, sels) =>
+              let val t' = typ_before explore params t in
+                if fastype_of1 (bound_Us, t') = YpreT then
+                  let
+                    val arg_ts' = map (typ_before explore params) arg_ts;
+                    val sels_t' = map (fn sel => betapply (sel, t')) sels;
+                    val Ts = map (curry fastype_of1 bound_Us) arg_ts';
+                    val Us = map (curry fastype_of1 bound_Us) sels_t';
+                    val arg_ts' = map2 encapsulate (map2 (update_UT params) Us Ts) arg_ts';
+                  in
+                    if forall check_is_VLeaf arg_ts' then
+                      SOME (Library.foldl1 HOLogic.mk_conj
+                        (betapply (disc, t') :: (map HOLogic.mk_eq (arg_ts' ~~ sels_t'))))
+                    else
+                      NONE
+                  end
+                else
+                  NONE
+              end
+            | NONE => NONE);
+        in
+          (case try_pattern_matching (strip_comb t1) t2 of
+            SOME cond => cond
+          | NONE => (case try_pattern_matching (strip_comb t2) t1 of
+              SOME cond => cond
+            | NONE =>
+              let
+                val T = fastype_of1 (bound_Ts, t1);
+                val params' = build_params bound_Us bound_Ts T;
+                val t1' = explore params' t1;
+                val t2' = explore params' t2;
+              in
+                if fastype_of1 (bound_Us, t1') = T andalso fastype_of1 (bound_Us, t2') = T then
+                  HOLogic.mk_eq (t1', t2')
+                else
+                  error ("Unsupported condition: " ^ quote (Syntax.string_of_term lthy t))
+              end))
+        end
+      | massage_equality explore params t = explore params t;
+
+    fun infer_types (TVar _) (TVar _) = []
+      | infer_types (U as TVar _) T = [(U, T)]
+      | infer_types (Type (s', Us)) (Type (s, Ts)) =
+        if s' = s then flat (map2 infer_types Us Ts) else []
+      | infer_types _ _ = [];
+
+    fun group_by_fst associations [] = associations
+      | group_by_fst associations ((a, b) :: r) = group_by_fst (add_association a b associations) r
+    and add_association a b [] = [(a, [b])]
+      | add_association a b ((c, d) :: r) =
+        if a = c then (c, b :: d) :: r
+        else (c, d) :: (add_association a b r);
+
+    fun new_TVar known_TVars =
+      Name.invent_list (map (fst o fst o dest_TVar) known_TVars) "x" 1
+      |> (fn [s] => TVar ((s, 0), []));
+
+    fun instantiate_type inferred_types =
+      Term.typ_subst_TVars (map (apfst (fst o dest_TVar)) inferred_types);
+
+    fun chose_unknown_TVar (T as TVar _) = SOME T
+      | chose_unknown_TVar (Type (_, Ts)) =
+        fold (curry merge_options) (map chose_unknown_TVar Ts) NONE
+      | chose_unknown_TVar _ = NONE;
+
+    (* The function under definition might not be defined yet when this is queried. *)
+    fun maybe_const_type ctxt (s, T) =
+      Sign.const_type (Proof_Context.theory_of ctxt) s |> the_default T;
+
+    fun massage_polymorphic_const explore (params as {bound_Us, ...}) t =
+      let val (fun_t, arg_ts) = strip_comb t in
+        (case fun_t of
+          Const (fun_x as (s, fun_T)) =>
+          let val general_T = maybe_const_type lthy fun_x in
+            if contains_res_T (body_type general_T) orelse is_constant t then
+              explore params t
+            else
+              let
+                val inferred_types = infer_types general_T fun_T;
+
+                fun prepare_skeleton [] _ = []
+                  | prepare_skeleton ((T, U) :: inferred_types) As =
+                    let
+                      fun schematize_res_T U As =
+                        if U = res_T then
+                          let val A = new_TVar As in
+                            (A, A :: As)
+                          end
+                        else
+                          (case U of
+                            Type (s, Us) => fold_map schematize_res_T Us As |>> curry Type s
+                          | _ => (U, As));
+
+                      val (U', As') = schematize_res_T U As;
+                    in
+                      (T, U') :: (prepare_skeleton inferred_types As')
+                    end;
+
+                val inferred_types' = prepare_skeleton inferred_types (map fst inferred_types);
+                val skeleton_T = instantiate_type inferred_types' general_T;
+
+                fun explore_if_possible (exp_arg as (_, true)) _ = exp_arg
+                  | explore_if_possible (exp_arg as (arg, false)) arg_T =
+                    if exists (exists_subtype is_TVar) (binder_types arg_T) then exp_arg
+                    else (typ_before (explore_fun (binder_types arg_T) explore) params arg, true);
+
+                fun collect_inferred_types [] _ = []
+                  | collect_inferred_types ((arg, explored) :: exp_arg_ts) (arg_T :: arg_Ts) =
+                    (if explored then infer_types arg_T (fastype_of1 (bound_Us, arg)) else []) @
+                    collect_inferred_types exp_arg_ts arg_Ts;
+
+                fun propagate exp_arg_ts skeleton_T =
+                  let
+                    val arg_gen_Ts = binder_types skeleton_T;
+                    val exp_arg_ts = map2 explore_if_possible exp_arg_ts arg_gen_Ts;
+                    val inferred_types = collect_inferred_types exp_arg_ts arg_gen_Ts
+                      |> group_by_fst []
+                      |> map (apsnd (deduce_according_type ssig_T));
+                  in
+                    (exp_arg_ts, instantiate_type inferred_types skeleton_T)
+                  end;
+
+                val remaining_to_be_explored = filter_out snd #> length;
+
+                fun try_exploring_args exp_arg_ts skeleton_T =
+                  let
+                    val n = remaining_to_be_explored exp_arg_ts;
+                    val (exp_arg_ts', skeleton_T') = propagate exp_arg_ts skeleton_T;
+                    val n' = remaining_to_be_explored exp_arg_ts';
+
+                    fun try_instantiating A T =
+                      try (try_exploring_args exp_arg_ts') (instantiate_type [(A, T)] skeleton_T');
+                  in
+                    if n' = 0 then
+                      SOME (exp_arg_ts', skeleton_T')
+                    else if n = n' then
+                      if exists_subtype is_TVar skeleton_T' then
+                        let val SOME A = chose_unknown_TVar skeleton_T' in
+                          (case try_instantiating A ssig_T of
+                            SOME result => result
+                          | NONE => (case try_instantiating A YpreT of
+                              SOME result => result
+                            | NONE => (case try_instantiating A res_T of
+                                SOME result => result
+                              | NONE => NONE)))
+                        end
+                      else
+                        NONE
+                    else
+                      try_exploring_args exp_arg_ts' skeleton_T'
+                  end;
+              in
+                (case try_exploring_args (map (fn arg => (arg, false)) arg_ts) skeleton_T of
+                  SOME (exp_arg_ts, fun_U) =>
+                  let
+                    val arg_ts' = map fst exp_arg_ts;
+                    val fun_t' = Const (s, fun_U);
+                    val t' = build_function_after_encapsulation fun_t fun_t' params arg_ts arg_ts';
+                  in
+                    (case try type_of1 (bound_Us, t') of
+                      SOME _ =>
+                      (if fun_T = fun_U orelse is_special_parametric_const (s, fun_T) then ()
+                       else add_parametric_const s general_T fun_T fun_U;
+                       t')
+                    | NONE => explore params t)
+                  end
+                | NONE => explore params t)
+              end
+          end
+        | _ => explore params t)
+      end;
+
+    fun massage_rho explore =
+      massage_star [massage_let, massage_if explore_cond, massage_case, massage_fun, massage_comp,
+          massage_map, massage_ctr, massage_sel, massage_disc, massage_equality,
+          massage_polymorphic_const]
+        explore
+    and massage_case explore (params as {bound_Ts, bound_Us, ...}) t =
+      (case strip_comb t of
+        (casex as Const (case_x as (c, _)), args as _ :: _ :: _) =>
+        (case try strip_fun_type (maybe_const_type lthy case_x) of
+          SOME (gen_branch_Ts, gen_body_fun_T) =>
+          let
+            val gen_branch_ms = map num_binder_types gen_branch_Ts;
+            val n = length gen_branch_ms;
+            val (branches, obj_leftovers) = chop n args;
+          in
+            if n < length args then
+              (case gen_body_fun_T of
+                Type (_, [Type (T_name, _), _]) =>
+                if case_of lthy T_name = SOME c then
+                  let
+                    val brancheTs = binder_fun_types (fastype_of1 (bound_Ts, casex));
+                    val obj_leftover_Ts = map (curry fastype_of1 bound_Ts) obj_leftovers;
+                    val obj_leftovers' =
+                      if is_constant (hd obj_leftovers) then
+                        obj_leftovers
+                      else
+                        (obj_leftover_Ts, obj_leftovers)
+                        |>> map (build_params bound_Us bound_Ts)
+                        |> op ~~
+                        |> map (uncurry explore_inner);
+                    val obj_leftoverUs = obj_leftovers' |> map (curry fastype_of1 bound_Us);
+
+                    val _ = is_valid_case_argumentT (hd obj_leftoverUs) orelse
+                      error (quote (Syntax.string_of_term lthy (hd obj_leftovers)) ^
+                        " is not a valid case argument");
+
+                    val Us = obj_leftoverUs |> hd |> dest_Type |> snd;
+
+                    val branche_binderUss =
+                      (if hd obj_leftoverUs = YpreT then mk_case HOLogic.boolT
+                       else update_case Us HOLogic.boolT casex)
+                      |> fastype_of
+                      |> binder_fun_types
+                      |> map binder_types;
+                    val b_params = map (build_params bound_Us bound_Ts) brancheTs;
+
+                    val branches' = branches
+                      |> @{map 4} explore_fun branche_binderUss (replicate n explore) b_params;
+                    val brancheUs = map (curry fastype_of1 bound_Us) branches';
+                    val U = deduce_according_type (body_type (hd brancheTs))
+                      (map body_type brancheUs);
+                    val casex' =
+                      if hd obj_leftoverUs = YpreT then mk_case U else update_case Us U casex;
+                  in
+                    build_function_after_encapsulation casex casex' params
+                      (branches @ obj_leftovers) (branches' @ obj_leftovers')
+                  end
+                else
+                  explore params t
+              | _ => explore params t)
+            else
+              explore params t
+          end
+        | NONE => explore params t)
+      | _ => explore params t)
+    and explore_cond params t =
+      if has_self_call t then
+        error ("Unallowed corecursive call in condition " ^ quote (Syntax.string_of_term lthy t))
+      else
+        explore_inner params t
+    and explore_inner params t =
+      massage_rho explore_inner_general params t
+    and explore_inner_general (params as {bound_Us, bound_Ts, T, ...}) t =
+      let val (fun_t, arg_ts) = strip_comb t in
+        if is_constant t then
+          t
+        else
+          (case (as_member_of discs fun_t,
+              length arg_ts = 1 andalso has_res_T bound_Ts (the_single arg_ts)) of
+            (SOME disc', true) =>
+            let
+              val arg' = explore_inner params (the_single arg_ts);
+              val arg_U = fastype_of1 (bound_Us, arg');
+            in
+              if arg_U = res_T then
+                fun_t $ arg'
+              else if arg_U = YpreT then
+                disc' $ arg'
+              else
+                error ("Discriminator " ^ quote (Syntax.string_of_term lthy fun_t) ^
+                  " cannot be applied to non-lhs argument " ^
+                  quote (Syntax.string_of_term lthy (hd arg_ts)))
+            end
+          | _ =>
+            (case as_member_of sels fun_t of
+              SOME sel' =>
+              let
+                val arg_ts' = map (explore_inner params) arg_ts;
+                val arg_U = fastype_of1 (bound_Us, hd arg_ts');
+              in
+                if arg_U = res_T then
+                  build_function_after_encapsulation fun_t fun_t params arg_ts arg_ts'
+                else if arg_U = YpreT then
+                  build_function_after_encapsulation fun_t sel' params arg_ts arg_ts'
+                else
+                  error ("Selector " ^ quote (Syntax.string_of_term lthy fun_t) ^
+                    " cannot be applied to non-lhs argument " ^
+                    quote (Syntax.string_of_term lthy (hd arg_ts)))
+              end
+            | NONE =>
+              (case as_member_of friends fun_t of
+                SOME (_, friend') =>
+                rebuild_function_after_exploration fun_t friend' explore_inner params arg_ts
+                |> curry (op $) Oper
+              | NONE =>
+                (case as_member_of ctr_guards fun_t of
+                  SOME ctr_guard' =>
+                  rebuild_function_after_exploration fun_t ctr_guard' explore_inner params arg_ts
+                  |> curry (op $) ctr_wrapper
+                  |> curry (op $) Oper
+                | NONE =>
+                  if is_Bound fun_t then
+                    rebuild_function_after_exploration fun_t fun_t explore_inner params arg_ts
+                  else if is_Free fun_t then
+                    let val fun_t' = map_types (fpT_to YpreT) fun_t in
+                      rebuild_function_after_exploration fun_t fun_t' explore_inner params arg_ts
+                    end
+                  else if T = res_T then
+                    error (quote (Syntax.string_of_term lthy fun_t) ^
+                      " not polymorphic enough to be applied like this and no friend")
+                  else
+                    error (quote (Syntax.string_of_term lthy fun_t) ^
+                      " not polymorphic enough to be applied like this")))))
+      end;
+
+    fun explore_ctr params t =
+      massage_rho explore_ctr_general params t
+    and explore_ctr_general params t =
+      let
+        val (fun_t, arg_ts) = strip_comb t;
+        val ctr_opt = as_member_of ctr_guards fun_t;
+      in
+        if is_some ctr_opt then
+          rebuild_function_after_exploration fun_t (the ctr_opt) explore_inner params arg_ts
+        else
+          error ("Constructor expected on right-hand side, " ^
+            quote (Syntax.string_of_term lthy fun_t) ^ " found instead")
+      end;
+
+    val rho_rhs = rhs
+      |> explore_ctr (build_params [] [] (fastype_of rhs))
+      |> abs_tuple_balanced (map (map_types (fpT_to YpreT)) lhs_args)
+      |> unfold_id_bnf_etc lthy;
+  in
+    lthy
+    |> define_const false b version rhoN rho_rhs
+    |>> pair (!parametric_consts, rho_rhs)
+  end;
+
+fun mk_rho_parametricity_goal ctxt Y Z preT ssig_T dead_pre_rel dead_k_rel dead_ssig_rel rho_rhs =
+  let
+    val YpreT = HOLogic.mk_prodT (Y, preT);
+    val ZpreT = Tsubst Y Z YpreT;
+    val ssigZ_T = Tsubst Y Z ssig_T;
+
+    val dead_pre_rel' = Term.subst_atomic_types [(Y, ssig_T), (Z, ssigZ_T)] dead_pre_rel;
+    val dead_k_rel' = Term.subst_atomic_types [(Y, YpreT), (Z, ZpreT)] dead_k_rel;
+
+    val (R, _) = ctxt
+      |> yield_singleton (mk_Frees "R") (mk_pred2T Y Z);
+
+    val rho_rel = mk_rel_fun (dead_k_rel' $ mk_rel_prod R (dead_pre_rel $ R))
+      (dead_pre_rel' $ (dead_ssig_rel $ R));
+    val rho_rhsZ = substT Y Z rho_rhs;
+  in
+    HOLogic.mk_Trueprop (rho_rel $ rho_rhs $ rho_rhsZ)
+  end;
+
+fun extract_rho_return_transfer_goals fun_b version dead_pre_bnf dead_k_bnf Y Z preT fun_T k_T
+    ssig_T ssig_fp_sugar friend_parse_info fun_t parsed_eq lthy =
+  let
+    val Type (fpT_name, _) = body_type fun_T;
+
+    fun mk_rel T bnf =
+      let
+        val ZT = Tsubst Y Z T;
+        val rel_T = mk_predT [mk_pred2T Y Z, T, ZT];
+      in
+        enforce_type lthy I rel_T (rel_of_bnf bnf)
+      end;
+
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+
+    val (dead_ssig_bnf, lthy) = bnf_kill_all_but 1 ssig_bnf lthy;
+
+    val dead_pre_rel = mk_rel preT dead_pre_bnf;
+    val dead_k_rel = mk_rel k_T dead_k_bnf;
+    val dead_ssig_rel = mk_rel ssig_T dead_ssig_bnf;
+
+    val (((parametric_consts, rho_rhs), rho_data), lthy) =
+      extract_rho_from_equation friend_parse_info fun_b version Y preT ssig_T fun_t parsed_eq lthy;
+
+    val const_transfer_goals = map (mk_const_transfer_goal lthy) parametric_consts;
+
+    val rho_transfer_goal =
+      mk_rho_parametricity_goal lthy Y Z preT ssig_T dead_pre_rel dead_k_rel dead_ssig_rel rho_rhs;
+  in
+    ((rho_data, (const_transfer_goals, rho_transfer_goal)), lthy)
+  end;
+
+fun explore_corec_equation ctxt could_be_friend friend fun_name fun_free
+    {outer_buffer, ctr_guards, inner_buffer} res_T (args, rhs) =
+  let
+    val is_self_call = curry (op aconv) fun_free;
+    val has_self_call = Term.exists_subterm is_self_call;
+
+    val outer_ssig_T = body_type (fastype_of (#Oper outer_buffer));
+
+    fun inner_fp_of (Free (s, _)) =
+      Free (s ^ inner_fp_suffix, mk_tupleT_balanced (map fastype_of args) --> outer_ssig_T);
+
+    fun build_params bound_Ts U T =
+      {bound_Us = bound_Ts, bound_Ts = bound_Ts, U = U, T = T};
+
+    fun rebuild_function_after_exploration new_fn explore {bound_Ts, ...} arg_ts =
+      let
+        val binder_types_old_fn = map (curry fastype_of1 bound_Ts) arg_ts;
+        val binder_types_new_fn = new_fn
+          |> binder_types o (curry fastype_of1 bound_Ts)
+          |> take (length binder_types_old_fn);
+        val paramss =
+          map2 (build_params bound_Ts) binder_types_new_fn binder_types_old_fn;
+      in
+        map2 explore paramss arg_ts
+        |> curry list_comb new_fn
+      end;
+
+    fun massage_map_corec explore {bound_Ts, U, T, ...} t =
+      let val explore' = explore ooo build_params in
+        massage_nested_corec_call ctxt has_self_call explore' explore' bound_Ts U T t
+      end;
+
+    fun massage_comp explore params t =
+      (case strip_comb t of
+        (Const (@{const_name comp}, _), f1 :: f2 :: args) =>
+        explore params (betapply (f1, (betapplys (f2, args))))
+      | _ => explore params t);
+
+    fun massage_fun explore (params as {bound_Us, bound_Ts, U, T}) t =
+      if can dest_funT T then
+        let
+          val arg_T = domain_type T;
+          val arg_name = the_default Name.uu (try (fn (Abs (s, _, _)) => s) t);
+        in
+          add_boundvar t
+          |> explore {bound_Us = arg_T :: bound_Us, bound_Ts = arg_T :: bound_Ts,
+             U = range_type U, T = range_type T}
+          |> (fn t => Abs (arg_name, arg_T, t))
+        end
+      else
+        explore params t
+
+    fun massage_let_if_case_corec explore {bound_Ts, U, T, ...} t =
+      massage_let_if_case ctxt has_self_call (fn bound_Ts => explore (build_params bound_Ts U T))
+        (K (unexpected_corec_call ctxt [t])) (K (unsupported_case_around_corec_call ctxt [t]))
+        bound_Ts t;
+
+    val massage_map_let_if_case =
+      massage_star [massage_map_corec, massage_fun, massage_comp, massage_let_if_case_corec];
+
+    fun explore_arg _ t =
+      if has_self_call t then
+        error (quote (Syntax.string_of_term ctxt t) ^ " contains a nested corecursive call" ^
+          (if could_be_friend then " (try specifying \"(friend)\")" else ""))
+      else
+        t;
+
+    fun explore_inner params t =
+      massage_map_let_if_case explore_inner_general params t
+    and explore_inner_general (params as {bound_Ts, T, ...}) t =
+      if T = res_T then
+        let val (f_t, arg_ts) = strip_comb t in
+          if has_self_call t then
+            (case as_member_of (#friends inner_buffer) f_t of
+              SOME (_, friend') =>
+              rebuild_function_after_exploration friend' explore_inner params arg_ts
+              |> curry (op $) (#Oper inner_buffer)
+            | NONE =>
+              (case as_member_of ctr_guards f_t of
+                SOME ctr_guard' =>
+                rebuild_function_after_exploration ctr_guard' explore_inner params arg_ts
+                |> curry (op $) (#ctr_wrapper inner_buffer)
+                |> curry (op $) (#Oper inner_buffer)
+              | NONE =>
+                if is_self_call f_t then
+                  if friend andalso exists has_self_call arg_ts then
+                    (case Symtab.lookup (#friends inner_buffer) fun_name of
+                      SOME (_, friend') =>
+                      rebuild_function_after_exploration friend' explore_inner params arg_ts
+                      |> curry (op $) (#Oper inner_buffer))
+                  else
+                    let val arg_Ts = binder_types (fastype_of1 (bound_Ts, f_t)) in
+                      map2 explore_arg (map2 (update_UT params) arg_Ts arg_Ts) arg_ts
+                      |> mk_tuple1_balanced bound_Ts
+                      |> curry (op $) (#VLeaf inner_buffer)
+                    end
+                else
+                  error (quote (Syntax.string_of_term ctxt f_t) ^ " not registered as friend")))
+          else
+            #CLeaf inner_buffer $ t
+        end
+      else if has_self_call t then
+        error (quote (Syntax.string_of_term ctxt t) ^ " contains a corecursive call but has type " ^
+          quote (Syntax.string_of_typ ctxt T))
+      else
+        explore_nested ctxt explore_inner_general params t;
+
+    fun explore_outer params t =
+      massage_map_let_if_case explore_outer_general params t
+    and explore_outer_general (params as {bound_Ts, T, ...}) t =
+      if T = res_T then
+        let val (f_t, arg_ts) = strip_comb t in
+          (case as_member_of ctr_guards f_t of
+            SOME ctr_guard' =>
+            rebuild_function_after_exploration ctr_guard' explore_inner params arg_ts
+            |> curry (op $) (#VLeaf outer_buffer)
+          | NONE =>
+            if not (has_self_call t) then
+              t
+              |> expand_to_ctr_term ctxt T
+              |> massage_let_if_case_corec explore_outer_general params
+            else
+              (case as_member_of (#friends outer_buffer) f_t of
+                SOME (_, friend') =>
+                rebuild_function_after_exploration friend' explore_outer params arg_ts
+                |> curry (op $) (#Oper outer_buffer)
+              | NONE =>
+                if is_self_call f_t then
+                  let val arg_Ts = binder_types (fastype_of1 (bound_Ts, f_t)) in
+                    map2 explore_arg (map2 (update_UT params) arg_Ts arg_Ts) arg_ts
+                    |> mk_tuple1_balanced bound_Ts
+                    |> curry (op $) (inner_fp_of f_t)
+                  end
+                else
+                  error (quote (Syntax.string_of_term ctxt f_t) ^ " not registered as friend")))
+        end
+      else if has_self_call t then
+        error (quote (Syntax.string_of_term ctxt t) ^ " contains a corecursive call but has type " ^
+          quote (Syntax.string_of_typ ctxt T))
+      else
+        explore_nested ctxt explore_outer_general params t;
+  in
+    (args, rhs
+      |> explore_outer (build_params [] outer_ssig_T res_T)
+      |> abs_tuple_balanced args)
+  end;
+
+fun mk_corec_fun_def_rhs ctxt arg_Ts corecUU0 corecUU_arg =
+  let val corecUU = enforce_type ctxt domain_type (fastype_of corecUU_arg) corecUU0 in
+    abs_curried_balanced arg_Ts (corecUU $ unfold_id_bnf_etc ctxt corecUU_arg)
+  end;
+
+fun get_options ctxt opts =
+  let
+    val plugins = get_first (fn Plugins_Option f => SOME (f ctxt) | _ => NONE) (rev opts)
+      |> the_default Plugin_Name.default_filter;
+    val friend = exists (can (fn Friend_Option => ())) opts;
+    val transfer = exists (can (fn Transfer_Option => ())) opts;
+  in
+    (plugins, friend, transfer)
+  end;
+
+fun add_function name parsed_eq lthy =
+  let
+    fun pat_completeness_auto ctxt =
+      Pat_Completeness.pat_completeness_tac ctxt 1 THEN auto_tac ctxt;
+
+    val ({defname, pelims = [[pelim]], pinducts = [pinduct], psimps = [psimp], ...}, lthy) =
+      Function.add_function [(Binding.concealed (Binding.name name), NONE, NoSyn)]
+        [(apfst Binding.concealed Attrib.empty_binding, parsed_eq)]
+        Function_Common.default_config pat_completeness_auto lthy;
+  in
+    ((defname, (pelim, pinduct, psimp)), lthy)
+  end;
+
+fun build_corecUU_arg_and_goals prove_termin (Free (fun_base_name, _)) (arg_ts, explored_rhs) lthy =
+  let
+    val inner_fp_name0 = fun_base_name ^ inner_fp_suffix;
+    val inner_fp_free = Free (inner_fp_name0, fastype_of explored_rhs);
+  in
+    if Term.exists_subterm (curry (op aconv) inner_fp_free) explored_rhs then
+      let
+        val arg = mk_tuple_balanced arg_ts;
+        val inner_fp_eq =
+          mk_Trueprop_eq (betapply (inner_fp_free, arg), betapply (explored_rhs, arg));
+
+        val ((inner_fp_name, (pelim, pinduct, psimp)), lthy') =
+          add_function inner_fp_name0 inner_fp_eq lthy;
+
+        fun mk_triple elim induct simp = ([elim], [induct], [simp]);
+
+        fun prepare_termin () =
+          let
+            val {goal, ...} = Proof.goal (Function.termination NONE lthy');
+            val termin_goal = goal |> Thm.concl_of |> Logic.unprotect |> Envir.beta_eta_contract;
+          in
+            (lthy', (mk_triple pelim pinduct psimp, [termin_goal]))
+          end;
+
+        val (lthy'', (inner_fp_triple, termin_goals)) =
+          if prove_termin then
+            (case try (Function.prove_termination NONE
+                (Function_Common.termination_prover_tac true lthy')) lthy' of
+              NONE => prepare_termin ()
+            | SOME ({elims = SOME [[elim]], inducts = SOME [induct], simps = SOME [simp], ...},
+                lthy'') =>
+              (lthy'', (mk_triple elim induct simp, [])))
+          else
+            prepare_termin ();
+
+        val inner_fp_const = (inner_fp_name, fastype_of explored_rhs)
+          |>> Proof_Context.read_const {proper = true, strict = false} lthy'
+          |> (fn (Const (s, _), T) => Const (s, T));
+      in
+        (((inner_fp_triple, termin_goals), inner_fp_const), lthy'')
+      end
+    else
+      (((([], [], []), []), explored_rhs), lthy)
+  end;
+
+fun derive_eq_corecUU ctxt {sig_fp_sugars, ssig_fp_sugar, eval, corecUU, eval_simps,
+      all_algLam_algs, corecUU_unique, ...}
+    fun_t corecUU_arg fun_code =
+  let
+    val fun_T = fastype_of fun_t;
+    val (arg_Ts, Type (fpT_name, _)) = strip_type fun_T;
+    val num_args = length arg_Ts;
+
+    val SOME {pre_bnf, fp_bnf, absT_info, fp_nesting_bnfs, live_nesting_bnfs, fp_ctr_sugar, ...} =
+      fp_sugar_of ctxt fpT_name;
+    val SOME {case_trivial, ...} = codatatype_extra_of ctxt fpT_name;
+
+    val ctr_sugar = #ctr_sugar fp_ctr_sugar;
+    val pre_map_def = map_def_of_bnf pre_bnf;
+    val abs_inverse = #abs_inverse absT_info;
+    val ctr_defs = #ctr_defs fp_ctr_sugar;
+    val case_eq_ifs = #case_eq_ifs ctr_sugar @ case_eq_if_thms_of_term ctxt (Thm.prop_of fun_code);
+    val all_sig_map_thms = maps (#map_thms o #fp_bnf_sugar) sig_fp_sugars;
+
+    val fp_map_ident = map_ident_of_bnf fp_bnf;
+    val fpsig_nesting_bnfs = fp_nesting_bnfs @ maps #live_nesting_bnfs sig_fp_sugars;
+    val fpsig_nesting_T_names = map (fst o dest_Type o T_of_bnf) fpsig_nesting_bnfs;
+    val fpsig_nesting_fp_sugars = map_filter (fp_sugar_of ctxt) fpsig_nesting_T_names;
+    val fpsig_nesting_fp_bnf_sugars = map #fp_bnf_sugar fpsig_nesting_fp_sugars;
+    val ssig_fp_bnf_sugar = #fp_bnf_sugar ssig_fp_sugar;
+    val ssig_bnf = #fp_bnf ssig_fp_sugar;
+    val ssig_map = map_of_bnf ssig_bnf;
+    val fpsig_nesting_maps = map map_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_ident0s = map map_ident0_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_comps = map map_comp_of_bnf fpsig_nesting_bnfs;
+    val fpsig_nesting_map_thms = maps #map_thms fpsig_nesting_fp_bnf_sugars;
+    val live_nesting_map_ident0s = map map_ident0_of_bnf live_nesting_bnfs;
+    val ssig_map_thms = #map_thms ssig_fp_bnf_sugar;
+    val all_algLam_alg_pointfuls = map (mk_pointful ctxt) all_algLam_algs;
+
+    val def_rhs = mk_corec_fun_def_rhs ctxt arg_Ts corecUU corecUU_arg;
+
+    val goal = mk_Trueprop_eq (fun_t, def_rhs);
+  in
+    Goal.prove_sorry ctxt [] [] goal (fn {context = ctxt, prems = _} =>
+      mk_eq_corecUU_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+        fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+        live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs all_sig_map_thms
+        ssig_map_thms all_algLam_alg_pointfuls (all_algrho_eqs_of ctxt) eval_simps corecUU_unique
+        fun_code)
+    |> Thm.close_derivation
+  end;
+
+fun derive_coinduct_cong_intros
+    ({fpT = fpT0 as Type (fpT_name, _), friend_names = friend_names0,
+      corecUU = Const (corecUU_name, _), dtor_coinduct_info as {dtor_coinduct, ...}, ...})
+    lthy =
+  let
+    val thy = Proof_Context.theory_of lthy;
+    val phi = Proof_Context.export_morphism lthy (Local_Theory.target_of lthy);
+
+    val fpT = Morphism.typ phi fpT0;
+    val general_fpT = body_type (Sign.the_const_type thy corecUU_name);
+    val most_general = Sign.typ_instance thy (general_fpT, fpT);
+  in
+    (case (most_general, coinduct_extra_of lthy corecUU_name) of
+      (true, SOME extra) => ((false, extra), lthy)
+    | _ =>
+      let
+        val ctr_names = ctr_names_of_fp_name lthy fpT_name;
+        val friend_names = friend_names0 |> map Long_Name.base_name |> rev;
+        val cong_intro_tab = derive_cong_intros lthy ctr_names friend_names dtor_coinduct_info;
+        val (coinduct, coinduct_attrs) = derive_coinduct lthy fpT0 dtor_coinduct;
+        val ((_, [coinduct]), lthy) = (* TODO check: only if most_general?*)
+          Local_Theory.note ((Binding.empty, coinduct_attrs), [coinduct]) lthy;
+
+        val extra = {coinduct = coinduct, coinduct_attrs = coinduct_attrs,
+          cong_intro_tab = cong_intro_tab};
+      in
+        ((most_general, extra), lthy |> most_general ? register_coinduct_extra corecUU_name extra)
+      end)
+  end;
+
+fun update_coinduct_cong_intross_dynamic fpT_name lthy =
+  let
+    val all_corec_infos = corec_infos_of lthy fpT_name;
+  in
+    lthy
+    |> fold_map (apfst snd oo derive_coinduct_cong_intros) all_corec_infos
+    |> snd
+  end;
+
+fun derive_and_update_coinduct_cong_intross [] = pair (false, [])
+  | derive_and_update_coinduct_cong_intross (corec_infos as {fpT = Type (fpT_name, _), ...} :: _) =
+    fold_map derive_coinduct_cong_intros corec_infos
+    #>> split_list
+    #> (fn ((changeds, extras), lthy) =>
+      if exists I changeds then
+        ((true, extras), lthy |> update_coinduct_cong_intross_dynamic fpT_name)
+      else
+        ((false, extras), lthy));
+
+fun prepare_corec_ursive_cmd long_cmd opts (raw_fixes, raw_eq) lthy =
+  let
+    val _ = can the_single raw_fixes orelse
+      error "Mutually corecursive functions not supported";
+
+    val (plugins, friend, transfer) = get_options lthy opts;
+    val ([((b, fun_T), mx)], [(_, eq)]) =
+      fst (Specification.read_spec raw_fixes [(Attrib.empty_binding, raw_eq)] lthy);
+
+    val _ = Sign.of_sort (Proof_Context.theory_of lthy) (fun_T, @{sort type}) orelse
+      error ("Type of " ^ Binding.print b ^ " contains top sort");
+
+    val (arg_Ts, res_T) = strip_type fun_T;
+    val fpT_name = (case res_T of Type (s, _) => s | _ => not_codatatype lthy res_T);
+    val fun_free = Free (Binding.name_of b, fun_T);
+    val parsed_eq = parse_corec_equation lthy [fun_free] eq;
+
+    val fun_name = Local_Theory.full_name lthy b;
+    val fun_t = Const (fun_name, fun_T);
+      (* FIXME: does this work with locales that fix variables? *)
+
+    val no_base = has_no_corec_info lthy fpT_name;
+    val lthy = lthy |> no_base ? setup_base fpT_name;
+
+    fun extract_rho lthy =
+      let
+        val lthy = lthy |> Variable.declare_typ fun_T;
+        val (prepared as (_, _, version, Y, Z, preT, k_T, ssig_T, dead_pre_bnf, dead_k_bnf, _,
+               ssig_fp_sugar, buffer), lthy) =
+          prepare_friend_corec fun_name fun_T lthy;
+        val friend_parse_info = friend_parse_info_of lthy arg_Ts res_T buffer;
+
+        val parsed_eq' = parsed_eq ||> subst_atomic [(fun_free, fun_t)];
+      in
+        lthy
+        |> extract_rho_return_transfer_goals b version dead_pre_bnf dead_k_bnf Y Z preT fun_T k_T
+          ssig_T ssig_fp_sugar friend_parse_info fun_t parsed_eq'
+        |>> pair prepared
+      end;
+
+    val ((prepareds, (rho_datas, transfer_goal_datas)), lthy) =
+      if friend then extract_rho lthy |>> (apfst single ##> (apfst single #> apsnd single))
+      else (([], ([], [])), lthy);
+
+    val ((buffer, corec_infos), lthy) =
+      if friend then
+        ((#13 (the_single prepareds), []), lthy)
+      else
+        corec_info_of res_T lthy
+        ||> no_base ? update_coinduct_cong_intross_dynamic fpT_name
+        |>> (fn info as {buffer, ...} => (buffer, [info]));
+
+    val corec_parse_info = corec_parse_info_of lthy arg_Ts res_T buffer;
+
+    val explored_eq =
+      explore_corec_equation lthy true friend fun_name fun_free corec_parse_info res_T parsed_eq;
+
+    val (((inner_fp_triple, termin_goals), corecUU_arg), lthy) =
+      build_corecUU_arg_and_goals (not long_cmd) fun_free explored_eq lthy;
+
+    fun def_fun (inner_fp_elims0, inner_fp_inducts0, inner_fp_simps0) const_transfers
+        rho_transfers_foldeds lthy =
+      let
+        fun register_friend lthy =
+          let
+            val [(old_corec_info, fp_b, version, Y, Z, _, k_T, _, _, dead_k_bnf, sig_fp_sugar,
+                  ssig_fp_sugar, _)] = prepareds;
+            val [(rho, rho_def)] = rho_datas;
+            val [(_, rho_transfer_goal)] = transfer_goal_datas;
+            val Type (fpT_name, _) = res_T;
+
+            val rho_transfer_folded =
+              (case rho_transfers_foldeds of
+                [] =>
+                derive_rho_transfer_folded lthy fpT_name const_transfers rho_def rho_transfer_goal
+              | [thm] => thm);
+          in
+            lthy
+            |> register_coinduct_dynamic_friend fpT_name fun_name
+            |> register_friend_corec fun_name fp_b version Y Z k_T dead_k_bnf sig_fp_sugar
+              ssig_fp_sugar fun_t rho rho_transfer_folded old_corec_info
+          end;
+
+        val (friend_infos, lthy) = lthy |> (if friend then register_friend #>> single else pair []);
+        val (corec_info as {corecUU = corecUU0, ...}, lthy) =
+          (case corec_infos of
+            [] => corec_info_of res_T lthy
+          | [info] => (info, lthy));
+
+        val def_rhs = mk_corec_fun_def_rhs lthy arg_Ts corecUU0 corecUU_arg;
+        val def = ((b, mx), ((Binding.concealed (Thm.def_binding b), []), def_rhs));
+
+        val ((fun_t0, (_, fun_def0)), (lthy, lthy_old)) = lthy
+          |> Local_Theory.open_target |> snd
+          |> Local_Theory.define def
+          ||> `Local_Theory.close_target;
+
+        val parsed_eq = parse_corec_equation lthy [fun_free] eq;
+        val views0 = generate_views lthy eq fun_free parsed_eq;
+
+        val lthy' = lthy |> fold Variable.declare_typ (res_T :: arg_Ts);
+        val phi = Proof_Context.export_morphism lthy_old lthy';
+
+        val fun_t = Morphism.term phi fun_t0; (* FIXME: shadows "fun_t" -- identical? *)
+        val fun_def = Morphism.thm phi fun_def0;
+        val inner_fp_elims = map (Morphism.thm phi) inner_fp_elims0;
+        val inner_fp_inducts = map (Morphism.thm phi) inner_fp_inducts0;
+        val inner_fp_simps = map (Morphism.thm phi) inner_fp_simps0;
+        val (code_goal, _, _, _, _) = morph_views phi views0;
+
+        fun derive_and_note_friend_extra_theorems lthy =
+          let
+            val k_T = #7 (the_single prepareds);
+            val rho_def = snd (the_single rho_datas);
+
+            val (eq_algrho, algrho_eq) = derive_eq_algrho lthy corec_info (the_single friend_infos)
+              fun_t k_T code_goal const_transfers rho_def fun_def;
+
+            val notes =
+              (if Config.get lthy bnf_internals then
+                 [(eq_algrhoN, [eq_algrho])]
+               else
+                 [])
+              |> map (fn (thmN, thms) =>
+                ((Binding.qualify true (Binding.name_of b)
+                    (Binding.qualify false friendN (Binding.name thmN)), []),
+                 [(thms, [])]));
+          in
+            lthy
+            |> register_friend_extra fun_name eq_algrho algrho_eq
+            |> Local_Theory.notes notes |> snd
+          end;
+
+        val lthy = lthy |> friend ? derive_and_note_friend_extra_theorems;
+
+        val code_thm = derive_code lthy inner_fp_simps code_goal corec_info res_T fun_t fun_def;
+(* TODO:
+        val ctr_thmss = map mk_thm (#2 views);
+        val disc_thmss = map mk_thm (#3 views);
+        val disc_iff_thmss = map mk_thm (#4 views);
+        val sel_thmss = map mk_thm (#5 views);
+*)
+
+        val uniques =
+          if null inner_fp_simps then [derive_unique lthy phi (#1 views0) corec_info res_T fun_def]
+          else [];
+
+(* TODO:
+        val disc_iff_or_disc_thmss =
+          map2 (fn [] => I | disc_iffs => K disc_iffs) disc_iff_thmss disc_thmss;
+        val simp_thmss = map2 append disc_iff_or_disc_thmss sel_thmss;
+*)
+
+        val ((_, [{cong_intro_tab, coinduct, coinduct_attrs}]), lthy) = lthy
+          |> derive_and_update_coinduct_cong_intross [corec_info];
+        val cong_intros_pairs = Symtab.dest cong_intro_tab;
+
+        val code_attrs = if plugins code_plugin then [Code.add_default_eqn_attrib] else [];
+
+        val anonymous_notes = [];
+(* TODO:
+          [(flat disc_iff_or_disc_thmss, simp_attrs)]
+          |> map (fn (thms, attrs) => ((Binding.empty, attrs), [(thms, [])]));
+*)
+
+        val notes =
+          [(cong_introsN, maps snd cong_intros_pairs, []),
+           (codeN, [code_thm], code_attrs @ nitpicksimp_attrs),
+           (coinductN, [coinduct], coinduct_attrs),
+           (inner_inductN, inner_fp_inducts, []),
+           (uniqueN, uniques, [])] @
+           map (fn (thmN, thms) => (thmN, thms, [])) cong_intros_pairs @
+          (if Config.get lthy bnf_internals then
+             [(inner_elimN, inner_fp_elims, []),
+              (inner_simpN, inner_fp_simps, [])]
+           else
+             [])
+(* TODO:
+           (ctrN, ctr_thms, []),
+           (discN, disc_thms, []),
+           (disc_iffN, disc_iff_thms, []),
+           (selN, sel_thms, simp_attrs),
+           (simpsN, simp_thms, []),
+*)
+          |> map (fn (thmN, thms, attrs) =>
+              ((Binding.qualify true (Binding.name_of b)
+                  (Binding.qualify false corecN (Binding.name thmN)), attrs),
+               [(thms, [])]))
+          |> filter_out (null o fst o hd o snd);
+      in
+        lthy
+(* TODO:
+        |> Spec_Rules.add Spec_Rules.Equational ([fun_t0], flat sel_thmss)
+        |> Spec_Rules.add Spec_Rules.Equational ([fun_t0], flat ctr_thmss)
+*)
+        |> Spec_Rules.add Spec_Rules.Equational ([fun_t0], [code_thm])
+        |> Local_Theory.notes (anonymous_notes @ notes)
+        |> snd
+      end;
+
+    fun prove_transfer_goal ctxt goal =
+      Variable.add_free_names ctxt goal []
+      |> (fn vars => Goal.prove_sorry (*FIXME*) (*no sorry*) ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+        HEADGOAL (Transfer.transfer_prover_tac ctxt)))
+      |> Thm.close_derivation;
+
+    fun maybe_prove_transfer_goal ctxt goal =
+      (case try (prove_transfer_goal ctxt) goal of
+        SOME thm => apfst (cons thm)
+      | NONE => apsnd (cons goal));
+
+    val const_transfer_goals = fold (union (op aconv) o fst) transfer_goal_datas [];
+    val (const_transfers, const_transfer_goals') =
+      if long_cmd then ([], const_transfer_goals)
+      else fold (maybe_prove_transfer_goal lthy) const_transfer_goals ([], []);
+  in
+    ((def_fun, (([res_T], prepareds, rho_datas, map snd transfer_goal_datas),
+        (inner_fp_triple, termin_goals), (const_transfers, const_transfer_goals'))), lthy)
+  end;
+
+fun corec_cmd opts (raw_fixes, raw_eq) lthy =
+  let
+    val ((def_fun, (_, (inner_fp_triple, termin_goals), (const_transfers, const_transfer_goals))),
+         lthy) =
+      prepare_corec_ursive_cmd false opts (raw_fixes, raw_eq) lthy;
+  in
+    if not (null termin_goals) then
+      error ("Termination prover failed (try " ^ quote (#1 @{command_keyword corecursive}) ^
+        " instead of " ^ quote (#1 @{command_keyword corec}) ^ ")")
+    else if not (null const_transfer_goals) then
+      error ("Transfer prover failed (try " ^ quote (#1 @{command_keyword corecursive}) ^
+        " instead of " ^ quote (#1 @{command_keyword corec}) ^ ")")
+    else
+      def_fun inner_fp_triple const_transfers [] lthy
+  end;
+
+fun corecursive_cmd opts (raw_fixes, raw_eq) lthy =
+  let
+    val ((def_fun, (([Type (fpT_name, _)], prepareds, rho_datas, rho_transfer_goals),
+            (inner_fp_triple, termin_goals), (const_transfers, const_transfer_goals))), lthy) =
+      prepare_corec_ursive_cmd true opts (raw_fixes, raw_eq) lthy;
+
+    val (rho_transfer_goals', unprime_rho_transfer_and_folds) =
+      @{map 3} (fn (_, _, _, _, _, _, _, _, _, _, _, _, _) => fn (_, rho_def) =>
+          prime_rho_transfer_goal lthy fpT_name rho_def)
+        prepareds rho_datas rho_transfer_goals
+      |> split_list;
+  in
+    Proof.theorem NONE (fn [termin_thms, const_transfers', rho_transfers'] =>
+      let
+        val remove_domain_condition =
+          full_simplify (put_simpset HOL_basic_ss lthy
+            addsimps (@{thm True_implies_equals} :: termin_thms));
+      in
+        def_fun (@{apply 3} (map remove_domain_condition) inner_fp_triple)
+          (const_transfers @ const_transfers')
+          (map2 (fn f => f) unprime_rho_transfer_and_folds rho_transfers')
+      end)
+      (map (map (rpair [])) [termin_goals, const_transfer_goals, rho_transfer_goals']) lthy
+  end;
+
+fun friend_of_corec_cmd ((raw_fun_name, raw_fun_T_opt), raw_eq) lthy =
+  let
+    val Const (fun_name, default_fun_T0) =
+      Proof_Context.read_const {proper = true, strict = false} lthy raw_fun_name;
+    val fun_T =
+      (case raw_fun_T_opt of
+        SOME raw_T => Syntax.read_typ lthy raw_T
+      | NONE => singleton (freeze_types lthy []) default_fun_T0);
+
+    val fun_t = Const (fun_name, fun_T);
+    val fun_b = Binding.name (Long_Name.base_name fun_name);
+
+    val fake_lthy = lthy |> Proof_Context.add_const_constraint (fun_name, SOME fun_T)
+      handle TYPE (msg, _, _) => error msg;
+
+    val code_goal = Syntax.read_prop fake_lthy raw_eq;
+
+    val (arg_Ts, res_T as Type (fpT_name, _)) = strip_type fun_T;
+
+    val no_base = has_no_corec_info lthy fpT_name;
+    val lthy = lthy |> no_base ? setup_base fpT_name;
+
+    val lthy = lthy |> Variable.declare_typ fun_T;
+    val ((old_corec_info, fp_b, version, Y, Z, preT, k_T, ssig_T, dead_pre_bnf, dead_k_bnf,
+          sig_fp_sugar, ssig_fp_sugar, buffer), lthy) =
+      prepare_friend_corec fun_name fun_T lthy;
+    val friend_parse_info = friend_parse_info_of lthy arg_Ts res_T buffer;
+
+    val parsed_eq = parse_corec_equation lthy [] code_goal;
+
+    val (((rho, rho_def), (const_transfer_goals, rho_transfer_goal)), lthy) =
+      extract_rho_return_transfer_goals fun_b version dead_pre_bnf dead_k_bnf Y Z preT fun_T k_T
+        ssig_T ssig_fp_sugar friend_parse_info fun_t parsed_eq lthy;
+
+    fun register_friend_extra_and_note_thms code_goal code_thm const_transfers k_T friend_info
+        lthy =
+      let
+        val (corec_info, lthy) = corec_info_of res_T lthy;
+
+        val fun_free = Free (Binding.name_of fun_b, fun_T);
+
+        fun freeze_fun (t as Const (s, _)) = if s = fun_name then fun_free else t
+          | freeze_fun t = t;
+
+        val eq = Term.map_aterms freeze_fun code_goal;
+        val parsed_eq = parse_corec_equation lthy [fun_free] eq;
+
+        val corec_parse_info = corec_parse_info_of lthy arg_Ts res_T buffer;
+        val explored_eq = explore_corec_equation lthy false false fun_name fun_free corec_parse_info
+          res_T parsed_eq;
+
+        val ((_, corecUU_arg), _) = build_corecUU_arg_and_goals false fun_free explored_eq lthy;
+
+        val eq_corecUU = derive_eq_corecUU lthy corec_info fun_t corecUU_arg code_thm;
+        val (eq_algrho, algrho_eq) = derive_eq_algrho lthy corec_info friend_info fun_t k_T
+          code_goal const_transfers rho_def eq_corecUU;
+
+        val ((_, [{cong_intro_tab, coinduct, coinduct_attrs}]), lthy) = lthy
+          |> register_friend_extra fun_name eq_algrho algrho_eq
+          |> register_coinduct_dynamic_friend fpT_name fun_name
+          |> derive_and_update_coinduct_cong_intross [corec_info];
+        val cong_intros_pairs = Symtab.dest cong_intro_tab;
+
+        val unique = derive_unique lthy Morphism.identity code_goal corec_info res_T eq_corecUU;
+
+        val notes =
+          [(cong_intros_friendN, maps snd cong_intros_pairs, []),
+           (codeN, [code_thm], []),
+           (coinductN, [coinduct], coinduct_attrs),
+           (uniqueN, [unique], [])] @
+           map (fn (thmN, thms) => (thmN, thms, [])) cong_intros_pairs @
+          (if Config.get lthy bnf_internals then
+             [(eq_algrhoN, [eq_algrho], []),
+              (eq_corecUUN, [eq_corecUU], [])]
+           else
+             [])
+          |> map (fn (thmN, thms, attrs) =>
+            ((Binding.qualify true (Binding.name_of fun_b)
+                (Binding.qualify false friendN (Binding.name thmN)), attrs),
+             [(thms, [])]));
+      in
+        lthy
+        |> Local_Theory.notes notes |> snd
+      end;
+
+    val (rho_transfer_goal', unprime_rho_transfer_and_fold) =
+      prime_rho_transfer_goal lthy fpT_name rho_def rho_transfer_goal;
+  in
+    lthy
+    |> Proof.theorem NONE (fn [[code_thm], const_transfers, [rho_transfer']] =>
+        register_friend_corec fun_name fp_b version Y Z k_T dead_k_bnf sig_fp_sugar ssig_fp_sugar
+          fun_t rho (unprime_rho_transfer_and_fold rho_transfer') old_corec_info
+        #-> register_friend_extra_and_note_thms code_goal code_thm const_transfers k_T)
+      (map (map (rpair [])) [[code_goal], const_transfer_goals, [rho_transfer_goal']])
+    |> Proof.refine_singleton (Method.primitive_text (K I))
+  end;
+
+fun coinduction_upto_cmd (base_name, raw_fpT) lthy =
+  let
+    val fpT as Type (fpT_name, _) = Syntax.read_typ lthy raw_fpT;
+
+    val no_base = has_no_corec_info lthy fpT_name;
+
+    val (corec_info as {version, ...}, lthy) = lthy
+      |> corec_info_of fpT;
+    val lthy = lthy |> no_base ? setup_base fpT_name;
+
+    val ((changed, [{cong_intro_tab, coinduct, coinduct_attrs}]), lthy) = lthy
+      |> derive_and_update_coinduct_cong_intross [corec_info];
+    val lthy = lthy |> (changed orelse no_base) ? update_coinduct_cong_intross_dynamic fpT_name;
+    val cong_intros_pairs = Symtab.dest cong_intro_tab;
+
+    val notes =
+      [(cong_introsN, maps snd cong_intros_pairs, []),
+       (coinduct_uptoN, [coinduct], coinduct_attrs)] @
+      map (fn (thmN, thms) => (thmN, thms, [])) cong_intros_pairs
+      |> map (fn (thmN, thms, attrs) =>
+        (((Binding.qualify true base_name
+            (Binding.qualify false ("v" ^ string_of_int version) (Binding.name thmN))), attrs),
+         [(thms, [])]));
+  in
+    lthy |> Local_Theory.notes notes |> snd
+  end;
+
+fun consolidate lthy =
+  let
+    val corec_infoss = map (corec_infos_of lthy o fst) (all_codatatype_extras_of lthy);
+    val (changeds, lthy) = lthy
+      |> fold_map (apfst fst oo derive_and_update_coinduct_cong_intross) corec_infoss;
+  in
+    if exists I changeds then lthy else raise Same.SAME
+  end;
+
+fun consolidate_global thy =
+  SOME (Named_Target.theory_map consolidate thy)
+  handle Same.SAME => NONE;
+
+val _ = Outer_Syntax.local_theory @{command_keyword corec}
+  "define nonprimitive corecursive functions"
+  ((Scan.optional (@{keyword "("} |-- Parse.!!! (Parse.list1 corec_option_parser)
+      --| @{keyword ")"}) []) -- (Parse.fixes --| Parse.where_ -- Parse.prop)
+   >> uncurry corec_cmd);
+
+val _ = Outer_Syntax.local_theory_to_proof @{command_keyword corecursive}
+  "define nonprimitive corecursive functions"
+  ((Scan.optional (@{keyword "("} |-- Parse.!!! (Parse.list1 corec_option_parser)
+      --| @{keyword ")"}) []) -- (Parse.fixes --| Parse.where_ -- Parse.prop)
+   >> uncurry corecursive_cmd);
+
+val _ = Outer_Syntax.local_theory_to_proof @{command_keyword friend_of_corec}
+  "register a function as a legal context for nonprimitive corecursion"
+  (Parse.const -- Scan.option (Parse.$$$ "::" |-- Parse.typ) --| Parse.where_ -- Parse.prop
+   >> friend_of_corec_cmd);
+
+val _ = Outer_Syntax.local_theory @{command_keyword coinduction_upto}
+  "derive a coinduction up-to principle and a corresponding congruence closure"
+  (Parse.name --| Parse.$$$ ":" -- Parse.typ >> coinduction_upto_cmd);
+
+val _ = Theory.setup (Theory.at_begin consolidate_global);
+
+end;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec_sugar_tactics.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,217 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec_tactics.ML
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Copyright   2016
+
+Tactics for generalized corecursor sugar.
+*)
+
+signature BNF_GFP_GREC_SUGAR_TACTICS =
+sig
+  val rho_transfer_simps: thm list
+
+  val mk_case_dtor_tac: Proof.context -> term -> thm -> thm -> thm list -> thm -> thm list -> tactic
+  val mk_cong_intro_ctr_or_friend_tac: Proof.context -> thm -> thm list -> thm -> tactic
+  val mk_code_tac: Proof.context -> int -> term list -> term -> term -> thm -> thm -> thm list ->
+    thm list -> thm list -> thm list -> thm -> thm -> thm list -> thm list -> thm -> thm list ->
+    thm list -> thm list -> thm list -> thm list -> thm list -> thm -> tactic
+  val mk_eq_algrho_tac: Proof.context -> term list -> term -> term -> term -> term -> term -> thm ->
+    thm -> thm list -> thm list -> thm list -> thm list -> thm -> thm -> thm -> thm list ->
+    thm list -> thm list -> thm -> thm list -> thm list -> thm list -> thm -> thm -> thm -> thm ->
+    thm list -> thm list -> thm list -> thm list -> thm list -> tactic
+  val mk_eq_corecUU_tac: Proof.context -> int -> term list -> term -> term -> thm -> thm ->
+    thm list -> thm list -> thm list -> thm list -> thm -> thm -> thm list -> thm list ->
+    thm list -> thm list -> thm list -> thm list -> thm list -> thm -> thm -> tactic
+  val mk_last_disc_tac: Proof.context -> term -> thm -> thm list -> tactic
+  val mk_rho_transfer_tac: Proof.context -> bool -> thm -> thm list -> tactic
+  val mk_unique_tac: Proof.context -> int -> term list -> term -> term -> thm -> thm -> thm list ->
+    thm list -> thm list -> thm list -> thm -> thm -> thm list -> thm list -> thm list ->
+    thm list -> thm list -> thm list -> thm list -> thm -> thm -> tactic
+end;
+
+structure BNF_GFP_Grec_Sugar_Tactics : BNF_GFP_GREC_SUGAR_TACTICS =
+struct
+
+open Ctr_Sugar
+open BNF_Util
+open BNF_Tactics
+open BNF_FP_Def_Sugar_Tactics
+open BNF_GFP_Grec_Tactics
+open BNF_GFP_Grec_Sugar_Util
+
+fun apply_func f =
+  let
+    val arg_Ts = binder_fun_types (fastype_of f);
+    val args = map_index (fn (j, T) => Var (("a" ^ string_of_int j, 0), T)) arg_Ts;
+  in
+    list_comb (f, args)
+  end;
+
+fun instantiate_distrib thm ctxt t =
+  Drule.infer_instantiate' ctxt [SOME (Thm.incr_indexes_cterm 1 (Thm.cterm_of ctxt t))] thm;
+
+(* TODO (here and elsewhere): Use metaequality in goal instead and keep uninstianted version of
+   theorem? *)
+val mk_if_distrib_of = instantiate_distrib @{thm if_distrib};
+val mk_case_sum_distrib_of = instantiate_distrib @{thm sum.case_distrib};
+
+fun mk_case_dtor_tac ctxt u abs_inverse dtor_ctor ctr_defs exhaust cases =
+  let val exhaust' = Drule.infer_instantiate' ctxt [SOME (Thm.cterm_of ctxt u)] exhaust in
+    HEADGOAL (rtac ctxt exhaust') THEN
+    REPEAT_DETERM (HEADGOAL (etac ctxt ssubst THEN'
+      SELECT_GOAL (unfold_thms_tac ctxt cases THEN
+        unfold_thms_tac ctxt (abs_inverse :: dtor_ctor :: ctr_defs @
+        @{thms prod.case sum.case})) THEN'
+      rtac ctxt refl))
+  end;
+
+fun mk_cong_intro_ctr_or_friend_tac ctxt ctr_or_friend_def extra_simps cong_alg_intro =
+  HEADGOAL (REPEAT_DETERM_N 2 o subst_tac ctxt NONE [ctr_or_friend_def] THEN'
+    rtac ctxt cong_alg_intro) THEN
+  unfold_thms_tac ctxt (extra_simps @ sumprod_thms_rel @
+    @{thms vimage2p_def prod.rel_eq sum.rel_eq}) THEN
+  REPEAT_DETERM (HEADGOAL (rtac ctxt conjI ORELSE' assume_tac ctxt ORELSE' rtac ctxt refl));
+
+val shared_simps =
+  @{thms map_prod_simp map_sum.simps sum.case prod.case_eq_if split_beta' prod.sel
+      sum.disc(1)[THEN eq_True[THEN iffD2]] sum.disc(2)[THEN eq_False[THEN iffD2]] sum.sel
+      isl_map_sum map_sum_sel if_True if_False if_True_False Let_def[abs_def] o_def[abs_def] id_def
+      BNF_Composition.id_bnf_def};
+
+fun mk_code_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+    fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+    live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs corecUU all_sig_maps
+    ssig_map_thms all_algLam_alg_pointfuls all_algrho_eqs eval_simps inner_fp_simps fun_def =
+  let
+    val fun_def' =
+      if null inner_fp_simps andalso num_args > 0 then
+        fun_def RS meta_eq_to_obj_eq RS (mk_curry_uncurryN_balanced ctxt num_args RS iffD2) RS sym
+      else
+        fun_def;
+    val case_trivial' = unfold_thms ctxt (case_eq_ifs @ ctr_defs @ shared_simps) case_trivial;
+    val case_eq_ifs' = map (Drule.abs_def o (fn thm => thm RS eq_reflection)) case_eq_ifs;
+    val if_distribs = @{thm if_distrib_fun} :: map (mk_if_distrib_of ctxt)
+      (eval :: map apply_func (ssig_map :: fpsig_nesting_maps));
+
+    val unfold_tac = unfold_thms_tac ctxt (case_trivial' :: pre_map_def :: abs_inverse ::
+      fp_map_ident :: (if null inner_fp_simps then [] else [corecUU]) @ fpsig_nesting_map_ident0s @
+      fpsig_nesting_map_comps @ fpsig_nesting_map_thms @ live_nesting_map_ident0s @ ctr_defs @
+      case_eq_ifs' @ all_sig_maps @ ssig_map_thms @ all_algLam_alg_pointfuls @ all_algrho_eqs @
+      eval_simps @ if_distribs @ shared_simps);
+  in
+    HEADGOAL (subst_tac ctxt NONE [fun_def] THEN' subst_tac ctxt NONE [corecUU] THEN'
+      (if null inner_fp_simps then K all_tac else subst_tac ctxt NONE inner_fp_simps)) THEN
+    unfold_thms_tac ctxt [fun_def'] THEN
+    unfold_tac THEN HEADGOAL (CONVERSION Thm.eta_long_conversion) THEN unfold_tac THEN
+    HEADGOAL (rtac ctxt refl)
+  end;
+
+fun mk_eq_algrho_tac ctxt fpsig_nesting_maps abs rep ctor ssig_map eval pre_map_def abs_inverse
+    fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+    live_nesting_map_ident0s fp_map_ident dtor_ctor ctor_iff_dtor ctr_defs nullary_disc_defs
+    disc_sel_eq_cases case_dtor case_eq_ifs const_pointful_naturals fp_nesting_k_map_disc_sels'
+    rho_def dtor_algrho corecUU_unique eq_corecUU all_sig_maps ssig_map_thms
+    all_algLam_alg_pointfuls all_algrho_eqs eval_simps =
+  let
+    fun mk_abs_def thm = Drule.abs_def (thm RS eq_reflection);
+
+    val nullary_disc_defs' = nullary_disc_defs
+      |> map (fn thm => thm RS sym)
+      |> maps (fn thm => [thm, thm RS @{thm subst[OF eq_commute, of "%e. e = z" for z]}]);
+
+    val case_dtor' = unfold_thms ctxt shared_simps case_dtor;
+    val disc_sel_eq_cases' = map (mk_abs_def
+      o unfold_thms ctxt (case_dtor' :: ctr_defs @ shared_simps)) disc_sel_eq_cases;
+    val const_pointful_naturals' = map (unfold_thms ctxt shared_simps) const_pointful_naturals;
+    val const_pointful_naturals_sym' = map (fn thm => thm RS sym) const_pointful_naturals';
+    val case_eq_ifs' = map mk_abs_def (@{thm sum.case_eq_if} :: case_eq_ifs);
+
+    val distrib_consts =
+      abs :: rep :: ctor :: eval :: map apply_func (ssig_map :: fpsig_nesting_maps);
+    val if_distribs = @{thm if_distrib_fun} :: map (mk_if_distrib_of ctxt) distrib_consts;
+    val case_sum_distribs = map (mk_case_sum_distrib_of ctxt) distrib_consts;
+
+    val simp_ctxt = (ctxt
+        |> Context_Position.set_visible false
+        |> put_simpset (simpset_of (Proof_Context.init_global @{theory Main}))
+        |> Raw_Simplifier.add_cong @{thm if_cong})
+      addsimps pre_map_def :: abs_inverse :: fp_map_ident :: dtor_ctor :: rho_def ::
+        @{thm convol_def} :: fpsig_nesting_map_ident0s @ fpsig_nesting_map_comps @
+        fpsig_nesting_map_thms @ live_nesting_map_ident0s @ ctr_defs @ disc_sel_eq_cases' @
+        fp_nesting_k_map_disc_sels' @ case_eq_ifs' @ all_sig_maps @ ssig_map_thms @
+        all_algLam_alg_pointfuls @ all_algrho_eqs @ eval_simps @ if_distribs @ case_sum_distribs @
+        shared_simps;
+
+    fun mk_main_simp const_pointful_naturals_maybe_sym' =
+      simp_tac (simp_ctxt addsimps const_pointful_naturals_maybe_sym');
+  in
+    unfold_thms_tac ctxt [eq_corecUU] THEN
+    HEADGOAL (REPEAT_DETERM o rtac ctxt ext THEN'
+      rtac ctxt (corecUU_unique RS sym RS fun_cong) THEN'
+      subst_tac ctxt NONE [dtor_algrho RS (ctor_iff_dtor RS iffD2)] THEN' rtac ctxt ext) THEN
+    unfold_thms_tac ctxt (nullary_disc_defs' @ shared_simps) THEN
+    HEADGOAL (rtac ctxt meta_eq_to_obj_eq) THEN
+    REPEAT_DETERM_N (length const_pointful_naturals' + 1)
+      (ALLGOALS (mk_main_simp const_pointful_naturals_sym') THEN
+       ALLGOALS (mk_main_simp const_pointful_naturals'))
+  end;
+
+fun mk_eq_corecUU_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+    fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+    live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs all_sig_maps
+    ssig_map_thms all_algLam_alg_pointfuls all_algrho_eqs eval_simps corecUU_unique fun_code =
+  let
+    val case_trivial' = unfold_thms ctxt (case_eq_ifs @ ctr_defs @ shared_simps) case_trivial;
+    val case_eq_ifs' = map (Drule.abs_def o (fn thm => thm RS eq_reflection)) case_eq_ifs;
+    val if_distribs = @{thm if_distrib_fun} :: map (mk_if_distrib_of ctxt)
+      (eval :: map apply_func (ssig_map :: fpsig_nesting_maps));
+
+    val unfold_tac = unfold_thms_tac ctxt (case_trivial' :: pre_map_def :: abs_inverse ::
+      fp_map_ident :: fpsig_nesting_map_ident0s @ fpsig_nesting_map_comps @ fpsig_nesting_map_thms @
+      live_nesting_map_ident0s @ ctr_defs @ case_eq_ifs' @ all_sig_maps @ ssig_map_thms @
+      all_algLam_alg_pointfuls @ all_algrho_eqs @ eval_simps @ if_distribs @ shared_simps);
+  in
+    HEADGOAL (rtac ctxt (mk_curry_uncurryN_balanced ctxt num_args RS iffD1) THEN'
+      rtac ctxt corecUU_unique THEN' rtac ctxt ext) THEN
+    unfold_thms_tac ctxt @{thms prod.case_eq_if} THEN
+    HEADGOAL (rtac ctxt (fun_code RS trans)) THEN
+    unfold_tac THEN HEADGOAL (CONVERSION Thm.eta_long_conversion) THEN unfold_tac THEN
+    HEADGOAL (rtac ctxt refl)
+  end;
+
+fun mk_last_disc_tac ctxt u exhaust discs' =
+  let val exhaust' = Drule.infer_instantiate' ctxt [SOME (Thm.cterm_of ctxt u)] exhaust in
+    HEADGOAL (rtac ctxt exhaust') THEN
+    REPEAT_DETERM (HEADGOAL (etac ctxt ssubst THEN'
+      simp_tac (ss_only (distinct Thm.eq_thm discs' @ @{thms simp_thms}) ctxt)))
+  end;
+
+val rho_transfer_simps = @{thms BNF_Def.vimage2p_def[abs_def] BNF_Composition.id_bnf_def};
+
+fun mk_rho_transfer_tac ctxt unfold rel_def const_transfers =
+  (if unfold then unfold_thms_tac ctxt (rel_def :: rho_transfer_simps) else all_tac) THEN
+  HEADGOAL (transfer_prover_add_tac ctxt [] const_transfers);
+
+fun mk_unique_tac ctxt num_args fpsig_nesting_maps ssig_map eval pre_map_def abs_inverse
+    fpsig_nesting_map_ident0s fpsig_nesting_map_comps fpsig_nesting_map_thms
+    live_nesting_map_ident0s fp_map_ident case_trivial ctr_defs case_eq_ifs all_sig_maps
+    ssig_map_thms all_algLam_alg_pointfuls all_algrho_eqs eval_simps corecUU_unique eq_corecUU =
+  let
+    val case_trivial' = unfold_thms ctxt (case_eq_ifs @ ctr_defs @ shared_simps) case_trivial;
+    val case_eq_ifs' = map (Drule.abs_def o (fn thm => thm RS eq_reflection)) case_eq_ifs;
+    val if_distribs = @{thm if_distrib_fun} :: map (mk_if_distrib_of ctxt)
+      (eval :: map apply_func (ssig_map :: fpsig_nesting_maps));
+
+    val unfold_tac = unfold_thms_tac ctxt (case_trivial' :: pre_map_def :: abs_inverse ::
+      fp_map_ident :: fpsig_nesting_map_ident0s @ fpsig_nesting_map_comps @ fpsig_nesting_map_thms @
+      live_nesting_map_ident0s @ ctr_defs @ case_eq_ifs' @ all_sig_maps @ ssig_map_thms @
+      all_algLam_alg_pointfuls @ all_algrho_eqs @ eval_simps @ if_distribs @ shared_simps);
+  in
+    HEADGOAL (subst_tac ctxt NONE [eq_corecUU] THEN'
+      rtac ctxt (mk_curry_uncurryN_balanced ctxt num_args RS iffD1) THEN'
+      rtac ctxt corecUU_unique THEN' rtac ctxt ext THEN'
+      etac ctxt @{thm ssubst[of _ _ "\<lambda>x. f x = u" for f u]}) THEN
+    unfold_tac THEN HEADGOAL (CONVERSION Thm.eta_long_conversion) THEN unfold_tac THEN
+    HEADGOAL (rtac ctxt refl)
+  end;
+
+end;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec_sugar_util.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,481 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec_sugar_util.ML
+    Author:     Aymeric Bouzy, Ecole polytechnique
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Copyright   2015, 2016
+
+Library for generalized corecursor sugar.
+*)
+
+signature BNF_GFP_GREC_SUGAR_UTIL =
+sig
+  type s_parse_info =
+    {outer_buffer: BNF_GFP_Grec.buffer,
+     ctr_guards: term Symtab.table,
+     inner_buffer: BNF_GFP_Grec.buffer}
+
+  type rho_parse_info =
+    {pattern_ctrs: (term * term list) Symtab.table,
+     discs: term Symtab.table,
+     sels: term Symtab.table,
+     it: term,
+     mk_case: typ -> term}
+
+  exception UNNATURAL of unit
+
+  val generalize_types: int -> typ -> typ -> typ
+  val mk_curry_uncurryN_balanced: Proof.context -> int -> thm
+  val mk_const_transfer_goal: Proof.context -> string * typ -> term
+  val mk_abs_transfer: Proof.context -> string -> thm
+  val mk_rep_transfer: Proof.context -> string -> thm
+  val mk_pointful_natural_from_transfer: Proof.context -> thm -> thm
+
+  val corec_parse_info_of: Proof.context -> typ list -> typ -> BNF_GFP_Grec.buffer -> s_parse_info
+  val friend_parse_info_of: Proof.context -> typ list -> typ -> BNF_GFP_Grec.buffer ->
+    s_parse_info * rho_parse_info
+end;
+
+structure BNF_GFP_Grec_Sugar_Util : BNF_GFP_GREC_SUGAR_UTIL =
+struct
+
+open Ctr_Sugar
+open BNF_Util
+open BNF_Tactics
+open BNF_Def
+open BNF_Comp
+open BNF_FP_Util
+open BNF_FP_Def_Sugar
+open BNF_GFP_Grec
+open BNF_GFP_Grec_Tactics
+
+val mk_case_sumN_balanced = Balanced_Tree.make mk_case_sum;
+
+fun not_codatatype ctxt T =
+  error ("Not a codatatype: " ^ Syntax.string_of_typ ctxt T);
+
+fun generalize_types max_j T U =
+  let
+    val vars = Unsynchronized.ref [];
+
+    fun var_of T U =
+      (case AList.lookup (op =) (!vars) (T, U) of
+        SOME V => V
+      | NONE =>
+        let val V = TVar ((Name.aT, length (!vars) + max_j), @{sort type}) in
+          vars := ((T, U), V) :: !vars; V
+        end);
+
+    fun gen (T as Type (s, Ts)) (U as Type (s', Us)) =
+        if s = s' then Type (s, map2 gen Ts Us) else var_of T U
+      | gen T U = if T = U then T else var_of T U;
+  in
+    gen T U
+  end;
+
+fun mk_curry_uncurryN_balanced_raw ctxt n =
+  let
+    val ((As, B), names_ctxt) = ctxt
+      |> mk_TFrees (n + 1)
+      |>> split_last;
+
+    val tupled_As = mk_tupleT_balanced As;
+
+    val f_T = As ---> B;
+    val g_T = tupled_As --> B;
+
+    val (((f, g), xs), _) = names_ctxt
+      |> yield_singleton (mk_Frees "f") f_T
+      ||>> yield_singleton (mk_Frees "g") g_T
+      ||>> mk_Frees "x" As;
+
+    val tupled_xs = mk_tuple1_balanced As xs;
+
+    val uncurried_f = mk_tupled_fun f tupled_xs xs;
+    val curried_g = abs_curried_balanced As g;
+
+    val lhs = HOLogic.mk_eq (uncurried_f, g);
+    val rhs =  HOLogic.mk_eq (f, curried_g);
+    val goal = fold_rev Logic.all [f, g] (mk_Trueprop_eq (lhs, rhs));
+
+    fun mk_tac ctxt =
+      HEADGOAL (rtac ctxt iffI THEN' dtac ctxt sym THEN' hyp_subst_tac ctxt) THEN
+      unfold_thms_tac ctxt @{thms prod.case} THEN
+      HEADGOAL (rtac ctxt refl THEN' hyp_subst_tac ctxt THEN'
+        REPEAT_DETERM o subst_tac ctxt NONE @{thms unit_abs_eta_conv case_prod_eta} THEN'
+        rtac ctxt refl);
+  in
+    Goal.prove_sorry ctxt [] [] goal (fn {context = ctxt, ...} => mk_tac ctxt)
+    |> Thm.close_derivation
+  end;
+
+val num_curry_uncurryN_balanced_precomp = 8;
+val curry_uncurryN_balanced_precomp =
+  map (mk_curry_uncurryN_balanced_raw @{context}) (0 upto num_curry_uncurryN_balanced_precomp);
+
+fun mk_curry_uncurryN_balanced ctxt n =
+  if n <= num_curry_uncurryN_balanced_precomp then nth curry_uncurryN_balanced_precomp n
+  else mk_curry_uncurryN_balanced_raw ctxt n;
+
+fun mk_const_transfer_goal ctxt (s, var_T) =
+  let
+    val var_As = Term.add_tvarsT var_T [];
+
+    val ((As, Bs), names_ctxt) = ctxt
+      |> Variable.declare_typ var_T
+      |> mk_TFrees' (map snd var_As)
+      ||>> mk_TFrees' (map snd var_As);
+
+    val (Rs, _) = names_ctxt
+      |> mk_Frees "R" (map2 mk_pred2T As Bs);
+
+    val T = Term.typ_subst_TVars (map fst var_As ~~ As) var_T;
+    val U = Term.typ_subst_TVars (map fst var_As ~~ Bs) var_T;
+  in
+    mk_parametricity_goal ctxt Rs (Const (s, T)) (Const (s, U))
+    |> tap (fn goal => can type_of goal orelse
+      error ("Cannot transfer constant " ^ quote (Syntax.string_of_term ctxt (Const (s, T))) ^
+        " from type " ^ quote (Syntax.string_of_typ ctxt T) ^ " to " ^
+        quote (Syntax.string_of_typ ctxt U)))
+  end;
+
+fun mk_abs_transfer ctxt fpT_name =
+  let
+    val SOME {pre_bnf, absT_info = {absT, repT, abs, type_definition, ...}, ...} =
+      fp_sugar_of ctxt fpT_name;
+  in
+    if absT = repT then
+      raise Fail "no abs/rep"
+    else
+      let
+        val rel_def = rel_def_of_bnf pre_bnf;
+
+        val absT = T_of_bnf pre_bnf
+          |> singleton (freeze_types ctxt (map dest_TVar (lives_of_bnf pre_bnf)));
+
+        val goal = mk_const_transfer_goal ctxt (dest_Const (mk_abs absT abs))
+      in
+        Variable.add_free_names ctxt goal []
+        |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+          unfold_thms_tac ctxt [rel_def] THEN
+          HEADGOAL (rtac ctxt (@{thm Abs_transfer} OF [type_definition, type_definition]))))
+      end
+  end;
+
+fun mk_rep_transfer ctxt fpT_name =
+  let
+    val SOME {pre_bnf, absT_info = {absT, repT, rep, ...}, ...} = fp_sugar_of ctxt fpT_name;
+  in
+    if absT = repT then
+      raise Fail "no abs/rep"
+    else
+      let
+        val rel_def = rel_def_of_bnf pre_bnf;
+
+        val absT = T_of_bnf pre_bnf
+          |> singleton (freeze_types ctxt (map dest_TVar (lives_of_bnf pre_bnf)));
+
+        val goal = mk_const_transfer_goal ctxt (dest_Const (mk_rep absT rep))
+      in
+        Variable.add_free_names ctxt goal []
+        |> (fn vars => Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+          unfold_thms_tac ctxt [rel_def] THEN
+          HEADGOAL (rtac ctxt @{thm vimage2p_rel_fun})))
+      end
+  end;
+
+exception UNNATURAL of unit;
+
+fun mk_pointful_natural_from_transfer ctxt transfer =
+  let
+    val _ $ (_ $ Const (s, T0) $ Const (_, U0)) = Thm.prop_of transfer;
+    val [T, U] = freeze_types ctxt [] [T0, U0];
+    val var_T = generalize_types 0 T U;
+
+    val var_As = map TVar (rev (Term.add_tvarsT var_T []));
+
+    val ((As, Bs), names_ctxt) = ctxt
+      |> mk_TFrees' (map Type.sort_of_atyp var_As)
+      ||>> mk_TFrees' (map Type.sort_of_atyp var_As);
+
+    val TA = typ_subst_atomic (var_As ~~ As) var_T;
+
+    val ((xs, fs), _) = names_ctxt
+      |> mk_Frees "x" (binder_types TA)
+      ||>> mk_Frees "f" (map2 (curry (op -->)) As Bs);
+
+    val AB_fs = (As ~~ Bs) ~~ fs;
+
+    fun build_applied_map TU t =
+      if op = TU then
+        t
+      else
+        (case try (build_map ctxt [] (the o AList.lookup (op =) AB_fs)) TU of
+          SOME mapx => mapx $ t
+        | NONE => raise UNNATURAL ());
+
+    fun unextensionalize (f $ (x as Free _), rhs) = unextensionalize (f, lambda x rhs)
+      | unextensionalize tu = tu;
+
+    val TB = typ_subst_atomic (var_As ~~ Bs) var_T;
+
+    val (binder_TAs, body_TA) = strip_type TA;
+    val (binder_TBs, body_TB) = strip_type TB;
+
+    val n = length var_As;
+    val m = length binder_TAs;
+
+    val A_nesting_bnfs = nesting_bnfs ctxt [[body_TA :: binder_TAs]] As;
+    val A_nesting_map_ids = map map_id_of_bnf A_nesting_bnfs;
+    val A_nesting_rel_Grps = map rel_Grp_of_bnf A_nesting_bnfs;
+
+    val ta = Const (s, TA);
+    val tb = Const (s, TB);
+    val xfs = @{map 3} (curry build_applied_map) binder_TAs binder_TBs xs;
+
+    val goal = (list_comb (tb, xfs), build_applied_map (body_TA, body_TB) (list_comb (ta, xs)))
+      |> unextensionalize |> mk_Trueprop_eq;
+
+    val _ = if can type_of goal then () else raise UNNATURAL ();
+
+    val vars = map (fst o dest_Free) (xs @ fs);
+  in
+    Goal.prove_sorry ctxt vars [] goal (fn {context = ctxt, prems = _} =>
+      mk_natural_from_transfer_tac ctxt m (replicate n true) transfer A_nesting_map_ids
+        A_nesting_rel_Grps [])
+    |> Thm.close_derivation
+  end;
+
+type s_parse_info =
+  {outer_buffer: BNF_GFP_Grec.buffer,
+   ctr_guards: term Symtab.table,
+   inner_buffer: BNF_GFP_Grec.buffer};
+
+type rho_parse_info =
+  {pattern_ctrs: (term * term list) Symtab.table,
+   discs: term Symtab.table,
+   sels: term Symtab.table,
+   it: term,
+   mk_case: typ -> term};
+
+fun curry_friend (T, t) =
+  let
+    val prod_T = domain_type (fastype_of t);
+    val Ts = dest_tupleT_balanced (num_binder_types T) prod_T;
+    val xs = map_index (fn (i, T) => Free ("x" ^ string_of_int i, T)) Ts;
+    val body = mk_tuple_balanced xs;
+  in
+    (T, fold_rev Term.lambda xs (t $ body))
+  end;
+
+fun curry_friends ({Oper, VLeaf, CLeaf, ctr_wrapper, friends} : buffer) =
+  {Oper = Oper, VLeaf = VLeaf, CLeaf = CLeaf, ctr_wrapper = ctr_wrapper,
+   friends = Symtab.map (K curry_friend) friends};
+
+fun checked_gfp_sugar_of lthy (T as Type (T_name, _)) =
+    (case fp_sugar_of lthy T_name of
+      SOME (sugar as {fp = Greatest_FP, ...}) => sugar
+    | _ => not_codatatype lthy T)
+  | checked_gfp_sugar_of lthy T = not_codatatype lthy T;
+
+fun generic_spec_of friend ctxt arg_Ts res_T (raw_buffer0 as {VLeaf = VLeaf0, ...}) =
+  let
+    val thy = Proof_Context.theory_of ctxt;
+
+    val tupled_arg_T = mk_tupleT_balanced arg_Ts;
+
+    val {T = fpT, X, fp_res_index, fp_res = {ctors = ctors0, ...},
+         absT_info = {abs = abs0, rep = rep0, ...},
+         fp_ctr_sugar = {ctrXs_Tss, ctr_sugar = {ctrs = ctrs0, casex = case0, discs = discs0,
+           selss = selss0, sel_defs, ...}, ...}, ...} =
+      checked_gfp_sugar_of ctxt res_T;
+
+    val VLeaf0_T = fastype_of VLeaf0;
+    val Y = domain_type VLeaf0_T;
+
+    val raw_buffer = specialize_buffer_types raw_buffer0;
+
+    val As_rho = tvar_subst thy [fpT] [res_T];
+
+    val substAT = Term.typ_subst_TVars As_rho;
+    val substA = Term.subst_TVars As_rho;
+    val substYT = Tsubst Y tupled_arg_T;
+    val substY = substT Y tupled_arg_T;
+
+    val Ys_rho_inner = if friend then [] else [(Y, tupled_arg_T)];
+    val substYT_inner = substAT o Term.typ_subst_atomic Ys_rho_inner;
+    val substY_inner = substA o Term.subst_atomic_types Ys_rho_inner;
+
+    val mid_T = substYT_inner (range_type VLeaf0_T);
+
+    val substXT_mid = Tsubst X mid_T;
+
+    val XifyT = typ_subst_nonatomic [(res_T, X)];
+    val YifyT = typ_subst_nonatomic [(res_T, Y)];
+
+    val substXYT = Tsubst X Y;
+
+    val ctor0 = nth ctors0 fp_res_index;
+    val ctor = enforce_type ctxt range_type res_T ctor0;
+    val preT = YifyT (domain_type (fastype_of ctor));
+
+    val n = length ctrs0;
+    val ks = 1 upto n;
+
+    fun mk_ctr_guards () =
+      let
+        val ctr_Tss = map (map (substXT_mid o substAT)) ctrXs_Tss;
+        val preT = XifyT (domain_type (fastype_of ctor));
+        val mid_preT = substXT_mid preT;
+        val abs = enforce_type ctxt range_type mid_preT abs0;
+        val absT = range_type (fastype_of abs);
+
+        fun mk_ctr_guard k ctr_Ts (Const (s, _)) =
+          let
+            val xs = map_index (fn (i, T) => Free ("x" ^ string_of_int i, T)) ctr_Ts;
+            val body = mk_absumprod absT abs n k xs;
+          in
+            (s, fold_rev Term.lambda xs body)
+          end;
+      in
+        Symtab.make (@{map 3} mk_ctr_guard ks ctr_Tss ctrs0)
+      end;
+
+    val substYT_mid = substYT o Tsubst Y mid_T;
+
+    val outer_T = substYT_mid preT;
+
+    val substY_outer = substY o substT Y outer_T;
+
+    val outer_buffer = curry_friends (map_buffer substY_outer raw_buffer);
+    val ctr_guards = mk_ctr_guards ();
+    val inner_buffer = curry_friends (map_buffer substY_inner raw_buffer);
+
+    val s_parse_info =
+      {outer_buffer = outer_buffer, ctr_guards = ctr_guards, inner_buffer = inner_buffer};
+
+    fun mk_friend_spec () =
+      let
+        fun encapsulate_nested U T free =
+          betapply (build_map ctxt [] (fn (T, _) =>
+              if T = domain_type VLeaf0_T then Abs (Name.uu, T, VLeaf0 $ Bound 0)
+              else Abs (Name.uu, T, Bound 0)) (T, U),
+            free);
+
+        val preT = YifyT (domain_type (fastype_of ctor));
+        val YpreT = HOLogic.mk_prodT (Y, preT);
+
+        val rep = rep0 |> enforce_type ctxt domain_type (substXT_mid (XifyT preT));
+
+        fun mk_disc k =
+          ctrXs_Tss
+          |> map_index (fn (i, Ts) =>
+            Abs (Name.uu, mk_tupleT_balanced Ts,
+              if i + 1 = k then @{const HOL.True} else @{const HOL.False}))
+          |> mk_case_sumN_balanced
+          |> map_types substXYT
+          |> (fn tm => Library.foldl1 HOLogic.mk_comp [tm, rep, snd_const YpreT])
+          |> map_types substAT;
+
+        val all_discs = map mk_disc ks;
+
+        fun mk_pair (Const (disc_name, _)) disc = SOME (disc_name, disc)
+          | mk_pair _ _ = NONE;
+
+        val discs = @{map 2} mk_pair discs0 all_discs
+          |> map_filter I |> Symtab.make;
+
+        fun mk_sel sel_def =
+          let
+            val (sel_name, case_functions) =
+              sel_def
+              |> Object_Logic.rulify ctxt
+              |> Thm.concl_of
+              |> perhaps (try drop_all)
+              |> perhaps (try HOLogic.dest_Trueprop)
+              |> HOLogic.dest_eq
+              |>> fst o strip_comb
+              |>> fst o dest_Const
+              ||> fst o dest_comb
+              ||> snd o strip_comb
+              ||> map (map_types (XifyT o substAT));
+
+            fun encapsulate_case_function case_function =
+              let
+                fun encapsulate bound_Ts [] case_function =
+                    let val T = fastype_of1 (bound_Ts, case_function) in
+                      encapsulate_nested (substXT_mid T) (substXYT T) case_function
+                    end
+                  | encapsulate bound_Ts (T :: Ts) case_function =
+                    Abs (Name.uu, T,
+                      encapsulate (T :: bound_Ts) Ts
+                        (betapply (incr_boundvars 1 case_function, Bound 0)));
+              in
+                encapsulate [] (binder_types (fastype_of case_function)) case_function
+              end;
+          in
+            (sel_name, ctrXs_Tss
+              |> map (map_index (fn (i, T) => Free ("x" ^ string_of_int (i + 1), T)))
+              |> `(map mk_tuple_balanced)
+              |> uncurry (@{map 3} mk_tupled_fun (map encapsulate_case_function case_functions))
+              |> mk_case_sumN_balanced
+              |> map_types substXYT
+              |> (fn tm => Library.foldl1 HOLogic.mk_comp [tm, rep, snd_const YpreT])
+              |> map_types substAT)
+          end;
+
+        val sels = Symtab.make (map mk_sel sel_defs);
+
+        fun mk_disc_sels_pair disc sels =
+          if forall is_some sels then SOME (disc, map the sels) else NONE;
+
+        val pattern_ctrs = (ctrs0, selss0)
+          ||> map (map (try dest_Const #> Option.mapPartial (fst #> Symtab.lookup sels)))
+          ||> @{map 2} mk_disc_sels_pair all_discs
+          |>> map (dest_Const #> fst)
+          |> op ~~
+          |> map_filter (fn (s, opt) => if is_some opt then SOME (s, the opt) else NONE)
+          |> Symtab.make;
+
+        val it = HOLogic.mk_comp (VLeaf0, fst_const YpreT);
+
+        val mk_case =
+          let
+            val abs_fun_tms = case0
+              |> fastype_of
+              |> substAT
+              |> XifyT
+              |> binder_fun_types
+              |> map_index (fn (i, T) => Free ("f" ^ string_of_int (i + 1), T));
+            val arg_Uss = abs_fun_tms
+              |> map fastype_of
+              |> map binder_types;
+            val arg_Tss = arg_Uss
+              |> map (map substXYT);
+            val case0 =
+              arg_Tss
+              |> map (map_index (fn (i, T) => Free ("x" ^ string_of_int (i + 1), T)))
+              |> `(map mk_tuple_balanced)
+              ||> @{map 3} (@{map 3} encapsulate_nested) arg_Uss arg_Tss
+              |> uncurry (@{map 3} mk_tupled_fun abs_fun_tms)
+              |> mk_case_sumN_balanced
+              |> (fn tm => Library.foldl1 HOLogic.mk_comp [tm, rep, snd_const YpreT])
+              |> fold_rev lambda abs_fun_tms
+              |> map_types (substAT o substXT_mid);
+          in
+            fn U => case0
+              |> substT (body_type (fastype_of case0)) U
+              |> Syntax.check_term ctxt
+          end;
+      in
+        {pattern_ctrs = pattern_ctrs, discs = discs, sels = sels, it = it, mk_case = mk_case}
+      end;
+  in
+    (s_parse_info, mk_friend_spec)
+  end;
+
+fun corec_parse_info_of ctxt =
+  fst ooo generic_spec_of false ctxt;
+
+fun friend_parse_info_of ctxt =
+  apsnd (fn f => f ()) ooo generic_spec_of true ctxt;
+
+end;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec_tactics.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,420 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec_tactics.ML
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Author:     Dmitriy Traytel, ETH Zurich
+    Copyright   2015, 2016
+
+Tactics for generalized corecursor construction.
+*)
+
+signature BNF_GFP_GREC_TACTICS =
+sig
+  val transfer_prover_add_tac: Proof.context -> thm list -> thm list -> int -> tactic
+
+  val mk_algLam_algLam_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    tactic
+  val mk_algLam_algrho_tac: Proof.context -> thm -> thm -> tactic
+  val mk_algLam_base_tac: Proof.context -> term -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm list -> thm -> thm list -> thm list -> thm -> thm -> tactic
+  val mk_algLam_step_tac: Proof.context -> thm -> thm -> thm -> tactic
+  val mk_cong_locale_tac: Proof.context -> thm -> thm list -> thm -> thm -> thm list -> thm ->
+    thm -> tactic
+  val mk_corecU_pointfree_tac: Proof.context -> thm -> thm -> thm list -> thm -> thm list -> thm ->
+    thm list -> thm -> thm -> thm -> tactic
+  val mk_corecUU_pointfree_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm -> thm -> thm -> thm -> thm -> thm -> tactic
+  val mk_corecUU_unique_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm -> thm -> thm -> thm -> thm -> thm -> tactic
+  val mk_corecUU_Inl_tac: Proof.context -> term -> thm -> thm -> thm -> thm -> thm list -> thm ->
+    thm list -> thm -> thm -> thm -> thm -> tactic
+  val mk_dtor_algLam_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm list ->
+    thm -> thm -> thm list -> thm -> thm -> thm -> thm -> tactic
+  val mk_dtor_algrho_tac: Proof.context -> thm -> thm -> thm -> thm -> tactic
+  val mk_dtor_transfer_tac: Proof.context -> thm -> tactic
+  val mk_equivp_Retr_tac: Proof.context -> thm -> thm -> thm -> thm -> tactic
+  val mk_eval_core_embL_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm -> thm -> thm -> thm list -> thm list -> thm list -> thm -> tactic
+  val mk_eval_core_flat_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm list -> thm -> thm list -> thm -> thm -> thm -> thm list -> tactic
+  val mk_eval_core_k_as_ssig_tac: Proof.context -> thm -> thm -> thm -> thm list -> thm -> thm ->
+    thm -> thm list -> tactic
+  val mk_eval_embL_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> tactic
+  val mk_eval_flat_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    tactic
+  val mk_eval_sctr_tac: Proof.context -> thm -> thm -> thm -> thm -> tactic
+  val mk_eval_Oper_tac: Proof.context -> int -> thm -> thm -> thm -> thm -> thm -> thm list ->
+    thm -> thm -> tactic
+  val mk_eval_V_or_CLeaf_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm list -> thm ->
+    tactic
+  val mk_extdd_mor_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm -> thm -> thm -> tactic
+  val mk_extdd_o_VLeaf_tac: Proof.context -> thm -> thm -> thm -> thm list -> thm list -> thm ->
+    thm -> thm -> tactic
+  val mk_flat_embL_tac: Proof.context -> thm -> thm -> thm -> thm -> thm -> thm list -> thm list ->
+    thm list -> thm list -> tactic
+  val mk_flat_VLeaf_or_flat_tac: Proof.context -> thm -> thm -> thm list -> tactic
+  val mk_Lam_Inl_Inr_tac: Proof.context -> thm -> thm -> tactic
+  val mk_mor_cutSsig_flat_tac: Proof.context -> term -> thm -> thm -> thm -> thm -> thm -> thm ->
+    thm list -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> thm -> tactic
+  val mk_natural_from_transfer_tac: Proof.context -> int -> bool list -> thm -> thm list ->
+    thm list -> thm list -> tactic
+  val mk_natural_by_unfolding_tac: Proof.context -> thm list -> tactic
+  val mk_Retr_coinduct_tac: Proof.context -> thm -> thm -> tactic
+  val mk_sig_transfer_tac: Proof.context -> thm -> thm list -> thm -> tactic
+  val mk_transfer_by_transfer_prover_tac: Proof.context -> thm list -> thm list -> thm list ->
+    tactic
+end;
+
+structure BNF_GFP_Grec_Tactics : BNF_GFP_GREC_TACTICS =
+struct
+
+open BNF_Util
+open BNF_Tactics
+open BNF_FP_Util
+
+val o_assoc = @{thm o_assoc};
+val o_def = @{thm o_def};
+
+fun ss_only_silent thms ctxt =
+  ss_only thms (ctxt |> Context_Position.set_visible false);
+
+fun context_relator_eq_add rel_eqs ctxt =
+  fold (snd oo Thm.proof_attributes (map (Attrib.attribute ctxt) @{attributes [relator_eq]}))
+    rel_eqs ctxt;
+val context_transfer_rule_add = fold (snd oo Thm.proof_attributes [Transfer.transfer_add]);
+
+fun transfer_prover_add_tac ctxt rel_eqs transfers =
+  Transfer.transfer_prover_tac (ctxt
+    |> context_relator_eq_add rel_eqs
+    |> context_transfer_rule_add transfers);
+
+fun instantiate_natural_rule_with_id ctxt live =
+  Rule_Insts.of_rule ctxt ([], NONE :: replicate live (SOME @{const_name id})) [];
+
+fun instantiate_transfer_rule_with_Grp_UNIV ctxt alives thm =
+  let
+    val n = length alives;
+    val fs = map (prefix "f" o string_of_int) (1 upto n);
+    val ss = map2 (fn live => fn f => SOME (@{const_name BNF_Def.Grp} ^ " " ^ @{const_name top} ^
+        " " ^ (if live then f else @{const_name id}))) alives fs;
+    val bs = map_filter (fn (live, f) => if live then SOME (Binding.name f, NONE, NoSyn) else NONE)
+      (alives ~~ fs);
+  in
+    Rule_Insts.of_rule ctxt ([], ss) bs thm
+  end;
+
+fun mk_algLam_algLam_tac ctxt dead_pre_map_comp dtor_inject unsig sig_map Lam_def eval_embL
+    old_dtor_algLam dtor_algLam =
+  HEADGOAL (rtac ctxt ext THEN' rtac ctxt (dtor_inject RS iffD1)) THEN
+  unfold_thms_tac ctxt (dead_pre_map_comp :: unsig :: sig_map :: Lam_def :: eval_embL ::
+    old_dtor_algLam :: dtor_algLam :: @{thms o_apply id_o map_sum.simps sum.case}) THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_algLam_algrho_tac ctxt algLam_def algrho_def =
+  HEADGOAL (rtac ctxt ext) THEN unfold_thms_tac ctxt [algLam_def, algrho_def, o_apply] THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_algLam_base_tac ctxt dead_pre_map_dtor dead_pre_map_id dead_pre_map_comp ctor_dtor dtor_ctor
+    dtor_unfold_unique unsig Sig_pointful_natural ssig_maps Lam_def flat_simps eval_core_simps eval
+    algLam_def =
+  HEADGOAL (rtac ctxt (infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt dead_pre_map_dtor)]
+    (trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym]) OF [ext, ext])) THEN
+  ALLGOALS (asm_simp_tac (ss_only_silent (dead_pre_map_id :: ctor_dtor :: dtor_ctor :: unsig ::
+    Sig_pointful_natural :: Lam_def :: eval :: algLam_def ::
+    unfold_thms ctxt [o_def] dead_pre_map_comp :: ssig_maps @ flat_simps @ eval_core_simps @
+    @{thms o_apply id_apply id_def[symmetric] snd_conv convol_apply}) ctxt));
+
+fun mk_algLam_step_tac ctxt proto_sctr_def old_algLam_pointful algLam_algLam_pointful =
+  HEADGOAL (rtac ctxt ext) THEN
+  unfold_thms_tac ctxt [proto_sctr_def, old_algLam_pointful, algLam_algLam_pointful, o_apply] THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_cong_locale_tac ctxt dead_pre_rel_mono dead_pre_rel_maps equivp_Retr
+    ssig_rel_mono ssig_rel_maps eval eval_core_transfer =
+  HEADGOAL (resolve_tac ctxt (Locale.get_unfolds @{context}) THEN'
+    etac ctxt ssig_rel_mono THEN' etac ctxt equivp_Retr) THEN
+  unfold_thms_tac ctxt (eval :: dead_pre_rel_maps @ @{thms id_apply}) THEN
+  HEADGOAL (rtac ctxt (@{thm predicate2I} RS (dead_pre_rel_mono RS @{thm predicate2D})) THEN'
+    etac ctxt @{thm rel_funD} THEN' assume_tac ctxt THEN'
+    rtac ctxt (eval_core_transfer RS @{thm rel_funD})) THEN
+  unfold_thms_tac ctxt (ssig_rel_maps @ @{thms vimage2p_rel_prod vimage2p_id}) THEN
+  unfold_thms_tac ctxt @{thms vimage2p_def} THEN HEADGOAL (assume_tac ctxt);
+
+fun mk_corecU_pointfree_tac ctxt dead_pre_map_comp dtor_unfold ssig_maps dead_ssig_map_comp0
+    flat_simps flat_VLeaf eval_core_simps cutSsig_def mor_cutSsig_flat corecU_def =
+  unfold_thms_tac ctxt [corecU_def, dead_ssig_map_comp0, o_assoc] THEN
+  HEADGOAL (subst_tac ctxt NONE [ext RS mor_cutSsig_flat] THEN'
+    asm_simp_tac (ss_only_silent [dtor_unfold, o_apply] ctxt) THEN'
+    asm_simp_tac (ss_only_silent (dtor_unfold :: flat_VLeaf :: cutSsig_def :: ssig_maps @
+      flat_simps @ eval_core_simps @ unfold_thms ctxt [o_def] dead_pre_map_comp ::
+      @{thms o_def id_apply id_def[symmetric] snd_conv convol_apply}) ctxt));
+
+fun mk_corecUU_tail_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor ssig_map_comp
+    flat_pointful_natural eval_core_pointful_natural eval eval_flat sctr_pointful_natural
+    eval_sctr_pointful =
+  asm_simp_tac (ss_only_silent (dtor_ctor :: flat_pointful_natural :: eval :: eval_flat ::
+    map (unfold_thms ctxt [o_def]) [dead_pre_map_comp, ssig_map_comp] @
+    @{thms o_apply id_apply id_def[symmetric] convol_apply}) ctxt) THEN'
+  asm_simp_tac (ss_only_silent (eval_core_pointful_natural :: sctr_pointful_natural ::
+    eval_sctr_pointful :: map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, ssig_map_comp] @
+    @{thms id_apply id_def[symmetric] convol_apply map_prod_simp}) ctxt);
+
+fun mk_corecUU_pointfree_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor dtor_inject
+    ssig_map_comp flat_pointful_natural eval_core_pointful_natural eval eval_flat corecU_ctor
+    sctr_pointful_natural eval_sctr_pointful corecUU_def =
+  unfold_thms_tac ctxt [corecUU_def] THEN
+  HEADGOAL (rtac ctxt ext THEN' subst_tac ctxt NONE [corecU_ctor RS sym]) THEN
+  unfold_thms_tac ctxt [corecUU_def RS Drule.symmetric_thm] THEN
+  HEADGOAL (rtac ctxt (dtor_inject RS iffD1) THEN'
+    mk_corecUU_tail_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor ssig_map_comp
+      flat_pointful_natural eval_core_pointful_natural eval eval_flat sctr_pointful_natural
+      eval_sctr_pointful);
+
+fun mk_corecUU_unique_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor ssig_map_comp
+    flat_pointful_natural eval_core_pointful_natural eval eval_flat corecU_unique
+    sctr_pointful_natural eval_sctr_pointful corecUU_def prem =
+  unfold_thms_tac ctxt [corecUU_def] THEN
+  HEADGOAL (rtac ctxt corecU_unique THEN' rtac ctxt sym THEN' subst_tac ctxt NONE [prem] THEN'
+    rtac ctxt ext THEN'
+    mk_corecUU_tail_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_ctor ssig_map_comp
+      flat_pointful_natural eval_core_pointful_natural eval eval_flat sctr_pointful_natural
+      eval_sctr_pointful);
+
+fun mk_corecUU_Inl_tac ctxt inl_case' pre_map_comp dead_pre_map_ident dead_pre_map_comp0 ctor_dtor
+    ssig_maps ssig_map_id0 eval_core_simps eval_core_pointful_natural eval_VLeaf corecUU_pointfree
+    corecUU_unique =
+  HEADGOAL (rtac ctxt (infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt inl_case')]
+      (trans OF [corecUU_unique, corecUU_unique RS sym]) OF [ext, ext]) THEN'
+    subst_tac ctxt NONE [corecUU_pointfree] THEN'
+    asm_simp_tac (ss_only_silent (dead_pre_map_comp0 :: eval_core_pointful_natural :: ssig_maps @
+      @{thms o_apply sum.case convol_apply id_apply map_prod_simp}) ctxt) THEN'
+    asm_simp_tac (ss_only_silent (dead_pre_map_ident :: ctor_dtor :: ssig_map_id0 ::
+        eval_core_pointful_natural :: eval_VLeaf :: unfold_thms ctxt [o_def] pre_map_comp ::
+        ssig_maps @ eval_core_simps @ @{thms o_apply prod.map_id convol_apply snd_conv id_apply})
+      ctxt));
+
+fun mk_dtor_algLam_tac ctxt pre_map_comp dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp
+    sig_map_comp Oper_pointful_natural ssig_maps dead_ssig_map_comp0 Lam_pointful_natural
+    eval_core_simps eval eval_flat eval_VLeaf algLam_def =
+  unfold_thms_tac ctxt [dead_ssig_map_comp0, o_assoc] THEN
+  HEADGOAL (asm_simp_tac (ss_only_silent (sig_map_comp :: Oper_pointful_natural :: eval ::
+      eval_flat :: algLam_def :: unfold_thms ctxt [o_def] dead_pre_map_comp :: eval_core_simps @
+      @{thms o_apply id_apply id_def[symmetric]}) ctxt) THEN'
+    asm_simp_tac (ss_only_silent (Lam_pointful_natural :: eval_VLeaf ::
+      map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, sig_map_comp] @ ssig_maps @
+      eval_core_simps @
+      @{thms o_apply convol_apply snd_conv fst_conv id_apply map_prod_simp}) ctxt) THEN'
+    asm_simp_tac (ss_only_silent (dead_pre_map_id :: eval_VLeaf ::
+      unfold_thms ctxt [o_def] pre_map_comp ::
+      @{thms id_apply id_def[symmetric] convol_def}) ctxt));
+
+fun mk_dtor_algrho_tac ctxt eval k_as_ssig_natural_pointful eval_core_k_as_ssig algrho_def =
+  HEADGOAL (asm_simp_tac (ss_only_silent [eval, k_as_ssig_natural_pointful, algrho_def,
+    eval_core_k_as_ssig RS sym, o_apply] ctxt));
+
+fun mk_dtor_transfer_tac ctxt dtor_rel =
+  HEADGOAL (rtac ctxt refl ORELSE'
+    rtac ctxt @{thm rel_funI} THEN' rtac ctxt (dtor_rel RS iffD1) THEN' assume_tac ctxt);
+
+fun mk_equivp_Retr_tac ctxt dead_pre_rel_refl dead_pre_rel_flip dead_pre_rel_mono
+    dead_pre_rel_compp =
+  HEADGOAL (EVERY' [etac ctxt @{thm equivpE}, rtac ctxt @{thm equivpI},
+    rtac ctxt @{thm reflpI}, rtac ctxt dead_pre_rel_refl, etac ctxt @{thm reflpD},
+    SELECT_GOAL (unfold_thms_tac ctxt @{thms symp_iff}),
+      REPEAT_DETERM o rtac ctxt ext, rtac ctxt (dead_pre_rel_flip RS sym RS trans),
+      rtac ctxt ((@{thm conversep_iff} RS sym) RSN (2, trans)),
+      asm_simp_tac (ss_only_silent @{thms conversep_eq} ctxt),
+    SELECT_GOAL (unfold_thms_tac ctxt @{thms transp_relcompp}),
+      rtac ctxt @{thm predicate2I}, etac ctxt @{thm relcomppE},
+      etac ctxt (dead_pre_rel_mono RS @{thm rev_predicate2D[rotated -1]}),
+      SELECT_GOAL (unfold_thms_tac ctxt
+        (unfold_thms ctxt [@{thm eq_OO}] dead_pre_rel_compp :: @{thms relcompp_apply})),
+      REPEAT_DETERM o resolve_tac ctxt [exI, conjI], assume_tac ctxt, assume_tac ctxt]);
+
+fun mk_eval_core_k_as_ssig_tac ctxt pre_map_comp dead_pre_map_id sig_map_comp ssig_maps
+    Lam_natural_pointful Lam_Inr flat_VLeaf eval_core_simps =
+  HEADGOAL (asm_simp_tac (ss_only_silent (dead_pre_map_id :: flat_VLeaf :: (Lam_Inr RS sym) ::
+    o_apply :: id_apply :: @{thm id_def[symmetric]} ::
+    unfold_thms ctxt @{thms map_prod_def split_def} Lam_natural_pointful :: ssig_maps @
+    eval_core_simps @ map (unfold_thms ctxt [o_def]) [pre_map_comp, sig_map_comp]) ctxt));
+
+fun mk_eval_embL_tac ctxt dead_pre_map_comp0 dtor_unfold_unique embL_pointful_natural eval_core_embL
+    old_eval eval =
+  HEADGOAL (rtac ctxt (unfold_thms ctxt [o_apply]
+      (trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym] OF [ext, ext])
+    OF [Drule.asm_rl, old_eval RS sym])) THEN
+  unfold_thms_tac ctxt [dead_pre_map_comp0, embL_pointful_natural, eval_core_embL, eval,
+    o_apply] THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_eval_flat_tac ctxt dead_pre_map_comp0 ssig_map_id ssig_map_comp flat_pointful_natural
+    eval_core_pointful_natural eval_core_flat eval cond_eval_o_flat =
+  HEADGOAL (rtac ctxt (unfold_thms ctxt [o_apply] cond_eval_o_flat)) THEN
+  unfold_thms_tac ctxt [dead_pre_map_comp0, flat_pointful_natural, eval_core_flat, eval,
+    o_apply] THEN
+  HEADGOAL (rtac ctxt refl THEN'
+    asm_simp_tac (ss_only_silent (ssig_map_id :: eval_core_pointful_natural :: eval ::
+        map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, ssig_map_comp] @
+        @{thms id_apply id_def[symmetric] fst_conv map_prod_simp convol_apply})
+      ctxt));
+
+fun instantiate_map_comp_with_f_g ctxt =
+  Rule_Insts.of_rule ctxt ([], [NONE, SOME ("%x. f (g x)")])
+    [(Binding.name "f", NONE, NoSyn), (Binding.name "g", NONE, NoSyn)];
+
+fun mk_eval_core_embL_tac ctxt old_ssig_induct dead_pre_map_comp0 dead_pre_map_comp
+    Sig_pointful_natural unsig_thm old_sig_map_comp old_sig_map_cong old_Lam_pointful_natural
+    Lam_def flat_embL old_eval_core_simps eval_core_simps embL_simps embL_pointful_natural =
+  HEADGOAL (rtac ctxt old_ssig_induct) THEN
+  ALLGOALS (asm_simp_tac (ss_only_silent (Sig_pointful_natural :: unsig_thm :: Lam_def ::
+    (flat_embL RS sym) :: unfold_thms ctxt [o_def] dead_pre_map_comp :: embL_simps @
+    old_eval_core_simps @ eval_core_simps @
+    @{thms id_apply id_def[symmetric] o_apply map_sum.simps sum.case}) ctxt)) THEN
+  HEADGOAL (asm_simp_tac (Simplifier.add_cong old_sig_map_cong (ss_only_silent
+    (old_Lam_pointful_natural :: embL_pointful_natural ::
+     map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, instantiate_map_comp_with_f_g ctxt
+       dead_pre_map_comp0, old_sig_map_comp] @ @{thms map_prod_simp}) ctxt)));
+
+fun mk_eval_core_flat_tac ctxt ssig_induct dead_pre_map_id dead_pre_map_comp0 dead_pre_map_comp
+    fp_map_id sig_map_comp sig_map_cong ssig_maps ssig_map_comp flat_simps flat_natural flat_flat
+    Lam_natural_sym eval_core_simps =
+  HEADGOAL (rtac ctxt ssig_induct) THEN
+  ALLGOALS (full_simp_tac (ss_only_silent ((flat_flat RS sym) :: dead_pre_map_id ::
+    dead_pre_map_comp :: fp_map_id :: sig_map_comp :: ssig_map_comp :: ssig_maps @ flat_simps @
+    eval_core_simps @ @{thms o_def id_def[symmetric] convol_apply id_apply snd_conv}) ctxt)) THEN
+  HEADGOAL (asm_simp_tac (Simplifier.add_cong sig_map_cong (ss_only_silent
+      (map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, sig_map_comp] @
+       flat_natural :: Lam_natural_sym :: @{thms id_apply fst_conv map_prod_simp})
+    ctxt)));
+
+fun mk_eval_sctr_tac ctxt proto_sctr_pointful_natural eval_Oper algLam sctr_def =
+  HEADGOAL (rtac ctxt ext) THEN
+  unfold_thms_tac ctxt [proto_sctr_pointful_natural, eval_Oper, algLam RS sym, sctr_def,
+    o_apply] THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_eval_V_or_CLeaf_tac ctxt dead_pre_map_id dead_pre_map_comp fp_map_id dtor_unfold_unique
+    V_or_CLeaf_map eval_core_simps eval =
+  HEADGOAL (rtac ctxt (trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym] RS fun_cong
+    OF [ext, ext])) THEN
+  ALLGOALS (asm_simp_tac (ss_only_silent (dead_pre_map_id :: fp_map_id ::
+    unfold_thms ctxt @{thms o_def} dead_pre_map_comp :: V_or_CLeaf_map :: eval :: eval_core_simps @
+    @{thms o_apply id_def[symmetric] id_apply snd_conv convol_apply}) ctxt));
+
+fun mk_eval_Oper_tac ctxt live sig_map_ident sig_map_comp0 sig_map_comp Oper_natural_pointful
+    VLeaf_natural flat_simps eval_flat algLam_def =
+  let val VLeaf_natural' = instantiate_natural_rule_with_id ctxt live VLeaf_natural in
+    unfold_thms_tac ctxt [sig_map_comp, VLeaf_natural', algLam_def, o_apply] THEN
+    unfold_thms_tac ctxt (sig_map_comp0 :: Oper_natural_pointful :: (eval_flat RS sym) :: o_apply ::
+      flat_simps) THEN
+    unfold_thms_tac ctxt (@{thm id_apply} :: sig_map_ident :: unfold_thms ctxt [o_def] sig_map_comp ::
+      flat_simps) THEN
+    HEADGOAL (rtac ctxt refl)
+  end;
+
+fun mk_extdd_mor_tac ctxt dead_pre_map_comp0 dead_pre_map_comp VLeaf_map ssig_map_comp
+    flat_pointful_natural eval_core_pointful_natural eval eval_flat eval_VLeaf cutSsig_def prem =
+  HEADGOAL (rtac ctxt ext) THEN
+  unfold_thms_tac ctxt (ssig_map_comp :: unfold_thms ctxt [o_def] dead_pre_map_comp ::
+    flat_pointful_natural :: eval :: eval_flat :: cutSsig_def ::
+    @{thms o_apply convol_o id_o id_apply id_def[symmetric]}) THEN
+  unfold_thms_tac ctxt (unfold_thms ctxt [dead_pre_map_comp0] prem :: dead_pre_map_comp0 ::
+    ssig_map_comp :: eval_core_pointful_natural ::
+    @{thms o_def[symmetric] o_apply map_prod_o_convol}) THEN
+  unfold_thms_tac ctxt (VLeaf_map :: eval_VLeaf :: @{thms o_def id_apply id_def[symmetric]}) THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_extdd_o_VLeaf_tac ctxt dead_pre_map_comp0 dead_pre_map_comp dtor_inject ssig_maps
+    eval_core_simps eval eval_VLeaf prem =
+  HEADGOAL (rtac ctxt ext THEN' rtac ctxt (dtor_inject RS iffD1) THEN'
+    asm_simp_tac (ss_only_silent (dead_pre_map_comp0 :: ssig_maps @ eval_core_simps @ eval ::
+      eval_VLeaf :: (mk_pointful ctxt prem RS sym) :: unfold_thms ctxt [o_def] dead_pre_map_comp ::
+      @{thms o_apply convol_apply snd_conv id_apply}) ctxt));
+
+fun mk_flat_embL_tac ctxt old_ssig_induct fp_map_id Sig_pointful_natural old_sig_map_comp
+    old_sig_map_cong old_ssig_maps old_flat_simps flat_simps embL_simps =
+  HEADGOAL (rtac ctxt old_ssig_induct) THEN
+  ALLGOALS (asm_simp_tac (Simplifier.add_cong old_sig_map_cong (ss_only_silent
+    (fp_map_id :: Sig_pointful_natural :: unfold_thms ctxt [o_def] old_sig_map_comp ::
+     old_ssig_maps @ old_flat_simps @ flat_simps @ embL_simps @
+     @{thms id_apply id_def[symmetric] map_sum.simps}) ctxt)));
+
+fun mk_flat_VLeaf_or_flat_tac ctxt ssig_induct cong simps =
+  HEADGOAL (rtac ctxt ssig_induct) THEN
+  ALLGOALS (asm_simp_tac (Simplifier.add_cong cong (ss_only_silent simps ctxt)));
+
+fun mk_Lam_Inl_Inr_tac ctxt unsig Lam_def =
+  TRYALL Goal.conjunction_tac THEN ALLGOALS (rtac ctxt ext) THEN
+  unfold_thms_tac ctxt (o_apply :: Lam_def :: unsig :: @{thms sum.case}) THEN
+  ALLGOALS (rtac ctxt refl);
+
+fun mk_mor_cutSsig_flat_tac ctxt eval_core_o_map dead_pre_map_comp0 dead_pre_map_comp
+    dead_pre_map_cong dtor_unfold_unique dead_ssig_map_comp0 ssig_map_comp flat_simps
+    flat_pointful_natural eval_core_pointful_natural flat_flat flat_VLeaf eval_core_flat cutSsig_def
+    cutSsig_def_pointful_natural eval_thm prem =
+  HEADGOAL (rtac ctxt (infer_instantiate' ctxt [NONE, SOME (Thm.cterm_of ctxt eval_core_o_map)]
+    (trans OF [dtor_unfold_unique, dtor_unfold_unique RS sym]) OF [ext, ext]) THEN'
+  asm_simp_tac (ss_only_silent ((prem RS sym) :: dead_pre_map_comp0 :: ssig_map_comp ::
+    eval_core_pointful_natural :: eval_thm ::
+    @{thms o_apply map_prod_o_convol o_id convol_o id_o}) ctxt) THEN'
+  asm_simp_tac (ss_only_silent ((mk_pointful ctxt prem RS sym) :: dead_pre_map_comp0 ::
+    cutSsig_def_pointful_natural :: flat_simps @
+    @{thms o_apply convol_apply map_prod_simp id_apply}) ctxt) THEN'
+  rtac ctxt (dead_pre_map_cong OF [Drule.asm_rl, refl]) THEN'
+  asm_simp_tac (ss_only_silent (ssig_map_comp :: cutSsig_def :: flat_pointful_natural ::
+    eval_core_flat :: unfold_thms ctxt [o_def] dead_pre_map_comp :: (dead_ssig_map_comp0 RS sym) ::
+    (flat_flat RS sym) ::
+    @{thms o_apply convol_o fst_convol id_apply id_def[symmetric]}) ctxt) THEN'
+  asm_simp_tac (ss_only_silent (eval_core_pointful_natural :: flat_VLeaf ::
+    map (unfold_thms ctxt [o_def]) [dead_pre_map_comp0, ssig_map_comp] @
+    @{thms o_apply id_apply id_def[symmetric] map_prod_simp convol_def}) ctxt));
+
+fun mk_natural_from_transfer_tac ctxt m alives transfer map_ids rel_Grps subst_rel_Grps =
+  let
+    val unfold_eq = unfold_thms ctxt @{thms Grp_UNIV_id[symmetric]};
+    val (rel_Grps', subst_rel_Grps') =
+      apply2 (map (fn thm => unfold_eq (thm RS eq_reflection))) (rel_Grps, subst_rel_Grps);
+    val transfer' = instantiate_transfer_rule_with_Grp_UNIV ctxt alives (unfold_eq transfer)
+      |> unfold_thms ctxt rel_Grps';
+  in
+    HEADGOAL (Method.insert_tac ctxt [transfer'] THEN'
+      EVERY' (map (subst_asm_tac ctxt NONE o single) subst_rel_Grps')) THEN
+    unfold_thms_tac ctxt (map_ids @ @{thms Grp_def rel_fun_def}) THEN
+    HEADGOAL (REPEAT_DETERM_N m o rtac ctxt ext THEN'
+      asm_full_simp_tac (ss_only_silent @{thms simp_thms id_apply o_apply mem_Collect_eq
+        top_greatest UNIV_I subset_UNIV[unfolded UNIV_def]} ctxt)) THEN
+    ALLGOALS (REPEAT_DETERM o etac ctxt @{thm meta_allE} THEN' REPEAT_DETERM o etac ctxt allE THEN'
+      forward_tac ctxt [sym] THEN' assume_tac ctxt)
+  end;
+
+fun mk_natural_by_unfolding_tac ctxt maps =
+  HEADGOAL (rtac ctxt ext) THEN
+  unfold_thms_tac ctxt (@{thms o_def[abs_def] id_apply id_def[symmetric]} @ maps) THEN
+  HEADGOAL (rtac ctxt refl);
+
+fun mk_Retr_coinduct_tac ctxt dtor_rel_coinduct rel_eq =
+  HEADGOAL (EVERY' [rtac ctxt allI, rtac ctxt impI,
+    rtac ctxt (@{thm ord_le_eq_trans} OF [dtor_rel_coinduct, rel_eq]),
+    etac ctxt @{thm predicate2D}, assume_tac ctxt]);
+
+fun mk_sig_transfer_tac ctxt pre_rel_def rel_eqs0 transfer =
+  let
+    val rel_eqs = no_refl rel_eqs0;
+    val rel_eq_syms = map (fn thm => thm RS sym) rel_eqs;
+    val transfer' = unfold_thms ctxt rel_eq_syms transfer
+  in
+    HEADGOAL (rtac ctxt transfer') ORELSE
+    unfold_thms_tac ctxt (pre_rel_def :: rel_eq_syms @
+      @{thms BNF_Def.vimage2p_def BNF_Composition.id_bnf_def}) THEN
+    HEADGOAL (rtac ctxt transfer')
+  end;
+
+fun mk_transfer_by_transfer_prover_tac ctxt defs rel_eqs0 transfers =
+  let
+    val rel_eqs = no_refl rel_eqs0;
+    val rel_eq_syms = map (fn thm => thm RS sym) rel_eqs;
+  in
+    unfold_thms_tac ctxt (defs @ rel_eq_syms) THEN
+    HEADGOAL (transfer_prover_add_tac ctxt rel_eqs transfers)
+  end;
+
+end;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/BNF/bnf_gfp_grec_unique_sugar.ML	Tue Mar 22 12:39:37 2016 +0100
@@ -0,0 +1,73 @@
+(*  Title:      HOL/Tools/BNF/bnf_gfp_grec_unique_sugar.ML
+    Author:     Jasmin Blanchette, Inria, LORIA, MPII
+    Copyright   2016
+
+Proof method for proving uniqueness of corecursive equations ("corec_unique").
+*)
+
+signature BNF_GFP_GREC_UNIQUE_SUGAR =
+sig
+  val corec_unique_tac: Proof.context -> int -> tactic
+end;
+
+structure BNF_GFP_Grec_Unique_Sugar : BNF_GFP_GREC_UNIQUE_SUGAR =
+struct
+
+open BNF_Util
+open BNF_GFP_Grec
+open BNF_GFP_Grec_Sugar_Util
+open BNF_GFP_Grec_Sugar
+
+fun corec_unique_tac ctxt =
+  Subgoal.FOCUS (fn {context = ctxt, prems, concl, ...} =>
+    let
+      (* Workaround for odd name clash for goals with "x" in their context *)
+      val (_, ctxt) = ctxt
+        |> yield_singleton (mk_Frees "x") @{typ unit};
+
+      val code_thm = (if null prems then error "No premise" else hd prems)
+        |> Object_Logic.rulify ctxt;
+      val code_goal = Thm.prop_of code_thm;
+
+      val (fun_t, args) = strip_comb (fst (HOLogic.dest_eq (HOLogic.dest_Trueprop code_goal)))
+        handle TERM _ => error "Wrong format for first premise";
+
+      val _ = is_Free fun_t orelse
+        error ("Expected free variable as function in premise, found " ^
+          Syntax.string_of_term ctxt fun_t);
+      val _ =
+        (case filter_out is_Var args of
+          [] => ()
+        | arg :: _ =>
+          error ("Expected universal variable as argument to function in premise, found " ^
+            Syntax.string_of_term ctxt arg));
+
+      val fun_T = fastype_of fun_t;
+      val (arg_Ts, res_T) = strip_type fun_T;
+
+      val num_args_in_concl = length (snd (strip_comb (fst (HOLogic.dest_eq
+          (HOLogic.dest_Trueprop (Thm.term_of concl))))))
+        handle TERM _ => error "Wrong format for conclusion";
+
+      val (corec_info, corec_parse_info) =
+        (case maybe_corec_info_of ctxt res_T of
+          SOME (info as {buffer, ...}) => (info, corec_parse_info_of ctxt arg_Ts res_T buffer)
+        | NONE => error ("No corecursor for " ^ quote (Syntax.string_of_typ ctxt res_T) ^
+          " (use " ^ quote (#1 @{command_keyword coinduction_upto}) ^ " to derive it)"));
+
+      val parsed_eq = parse_corec_equation ctxt [fun_t] code_goal;
+      val explored_eq =
+        explore_corec_equation ctxt false false "" fun_t corec_parse_info res_T parsed_eq;
+
+      val ((_, corecUU_arg), _) = build_corecUU_arg_and_goals false fun_t explored_eq ctxt;
+      val eq_corecUU = derive_eq_corecUU ctxt corec_info fun_t corecUU_arg code_thm;
+
+      val unique' = derive_unique ctxt Morphism.identity code_goal corec_info res_T eq_corecUU
+        |> funpow num_args_in_concl (fn thm => thm RS fun_cong);
+    in
+      HEADGOAL ((K all_tac APPEND' rtac ctxt sym) THEN' rtac ctxt unique' THEN'
+        REPEAT_DETERM_N num_args_in_concl o rtac ctxt ext)
+    end) ctxt THEN'
+  etac ctxt thin_rl;
+
+end;