src/HOL/Tools/ATP/atp_problem_generate.ML
changeset 46320 0b8b73b49848
parent 46301 e2e52c7d25c9
child 46338 b02ff6b17599
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/ATP/atp_problem_generate.ML	Mon Jan 23 17:40:32 2012 +0100
@@ -0,0 +1,2557 @@
+(*  Title:      HOL/Tools/ATP/atp_problem_generate.ML
+    Author:     Fabian Immler, TU Muenchen
+    Author:     Makarius
+    Author:     Jasmin Blanchette, TU Muenchen
+
+Translation of HOL to FOL for Metis and Sledgehammer.
+*)
+
+signature ATP_PROBLEM_GENERATE =
+sig
+  type ('a, 'b) ho_term = ('a, 'b) ATP_Problem.ho_term
+  type connective = ATP_Problem.connective
+  type ('a, 'b, 'c) formula = ('a, 'b, 'c) ATP_Problem.formula
+  type atp_format = ATP_Problem.atp_format
+  type formula_kind = ATP_Problem.formula_kind
+  type 'a problem = 'a ATP_Problem.problem
+
+  datatype locality =
+    General | Helper | Induction | Intro | Elim | Simp | Local | Assum | Chained
+
+  datatype polymorphism = Polymorphic | Raw_Monomorphic | Mangled_Monomorphic
+  datatype strictness = Strict | Non_Strict
+  datatype granularity = All_Vars | Positively_Naked_Vars | Ghost_Type_Arg_Vars
+  datatype type_level =
+    All_Types |
+    Noninf_Nonmono_Types of strictness * granularity |
+    Fin_Nonmono_Types of granularity |
+    Const_Arg_Types |
+    No_Types
+  type type_enc
+
+  val type_tag_idempotence : bool Config.T
+  val type_tag_arguments : bool Config.T
+  val no_lamsN : string
+  val hide_lamsN : string
+  val lam_liftingN : string
+  val combinatorsN : string
+  val hybrid_lamsN : string
+  val keep_lamsN : string
+  val schematic_var_prefix : string
+  val fixed_var_prefix : string
+  val tvar_prefix : string
+  val tfree_prefix : string
+  val const_prefix : string
+  val type_const_prefix : string
+  val class_prefix : string
+  val lam_lifted_prefix : string
+  val lam_lifted_mono_prefix : string
+  val lam_lifted_poly_prefix : string
+  val skolem_const_prefix : string
+  val old_skolem_const_prefix : string
+  val new_skolem_const_prefix : string
+  val combinator_prefix : string
+  val type_decl_prefix : string
+  val sym_decl_prefix : string
+  val guards_sym_formula_prefix : string
+  val tags_sym_formula_prefix : string
+  val fact_prefix : string
+  val conjecture_prefix : string
+  val helper_prefix : string
+  val class_rel_clause_prefix : string
+  val arity_clause_prefix : string
+  val tfree_clause_prefix : string
+  val lam_fact_prefix : string
+  val typed_helper_suffix : string
+  val untyped_helper_suffix : string
+  val type_tag_idempotence_helper_name : string
+  val predicator_name : string
+  val app_op_name : string
+  val type_guard_name : string
+  val type_tag_name : string
+  val simple_type_prefix : string
+  val prefixed_predicator_name : string
+  val prefixed_app_op_name : string
+  val prefixed_type_tag_name : string
+  val ascii_of : string -> string
+  val unascii_of : string -> string
+  val unprefix_and_unascii : string -> string -> string option
+  val proxy_table : (string * (string * (thm * (string * string)))) list
+  val proxify_const : string -> (string * string) option
+  val invert_const : string -> string
+  val unproxify_const : string -> string
+  val new_skolem_var_name_from_const : string -> string
+  val atp_irrelevant_consts : string list
+  val atp_schematic_consts_of : term -> typ list Symtab.table
+  val is_type_enc_higher_order : type_enc -> bool
+  val polymorphism_of_type_enc : type_enc -> polymorphism
+  val level_of_type_enc : type_enc -> type_level
+  val is_type_enc_quasi_sound : type_enc -> bool
+  val is_type_enc_fairly_sound : type_enc -> bool
+  val type_enc_from_string : strictness -> string -> type_enc
+  val adjust_type_enc : atp_format -> type_enc -> type_enc
+  val mk_aconns :
+    connective -> ('a, 'b, 'c) formula list -> ('a, 'b, 'c) formula
+  val unmangled_const : string -> string * (string, 'b) ho_term list
+  val unmangled_const_name : string -> string
+  val helper_table : ((string * bool) * thm list) list
+  val trans_lams_from_string :
+    Proof.context -> type_enc -> string -> term list -> term list * term list
+  val factsN : string
+  val prepare_atp_problem :
+    Proof.context -> atp_format -> formula_kind -> formula_kind -> type_enc
+    -> bool -> string -> bool -> bool -> term list -> term
+    -> ((string * locality) * term) list
+    -> string problem * string Symtab.table * (string * locality) list vector
+       * (string * term) list * int Symtab.table
+  val atp_problem_weights : string problem -> (string * real) list
+end;
+
+structure ATP_Problem_Generate : ATP_PROBLEM_GENERATE =
+struct
+
+open ATP_Util
+open ATP_Problem
+
+type name = string * string
+
+val type_tag_idempotence =
+  Attrib.setup_config_bool @{binding atp_type_tag_idempotence} (K false)
+val type_tag_arguments =
+  Attrib.setup_config_bool @{binding atp_type_tag_arguments} (K false)
+
+val no_lamsN = "no_lams" (* used internally; undocumented *)
+val hide_lamsN = "hide_lams"
+val lam_liftingN = "lam_lifting"
+val combinatorsN = "combinators"
+val hybrid_lamsN = "hybrid_lams"
+val keep_lamsN = "keep_lams"
+
+(* It's still unclear whether all TFF1 implementations will support type
+   signatures such as "!>[A : $tType] : $o", with ghost type variables. *)
+val avoid_first_order_ghost_type_vars = false
+
+val bound_var_prefix = "B_"
+val all_bound_var_prefix = "BA_"
+val exist_bound_var_prefix = "BE_"
+val schematic_var_prefix = "V_"
+val fixed_var_prefix = "v_"
+val tvar_prefix = "T_"
+val tfree_prefix = "t_"
+val const_prefix = "c_"
+val type_const_prefix = "tc_"
+val simple_type_prefix = "s_"
+val class_prefix = "cl_"
+
+(* Freshness almost guaranteed! *)
+val atp_weak_prefix = "ATP:"
+
+val lam_lifted_prefix = atp_weak_prefix ^ "Lam"
+val lam_lifted_mono_prefix = lam_lifted_prefix ^ "m"
+val lam_lifted_poly_prefix = lam_lifted_prefix ^ "p"
+
+val skolem_const_prefix = "ATP" ^ Long_Name.separator ^ "Sko"
+val old_skolem_const_prefix = skolem_const_prefix ^ "o"
+val new_skolem_const_prefix = skolem_const_prefix ^ "n"
+
+val combinator_prefix = "COMB"
+
+val type_decl_prefix = "ty_"
+val sym_decl_prefix = "sy_"
+val guards_sym_formula_prefix = "gsy_"
+val tags_sym_formula_prefix = "tsy_"
+val fact_prefix = "fact_"
+val conjecture_prefix = "conj_"
+val helper_prefix = "help_"
+val class_rel_clause_prefix = "clar_"
+val arity_clause_prefix = "arity_"
+val tfree_clause_prefix = "tfree_"
+
+val lam_fact_prefix = "ATP.lambda_"
+val typed_helper_suffix = "_T"
+val untyped_helper_suffix = "_U"
+val type_tag_idempotence_helper_name = helper_prefix ^ "ti_idem"
+
+val predicator_name = "pp"
+val app_op_name = "aa"
+val type_guard_name = "gg"
+val type_tag_name = "tt"
+
+val prefixed_predicator_name = const_prefix ^ predicator_name
+val prefixed_app_op_name = const_prefix ^ app_op_name
+val prefixed_type_tag_name = const_prefix ^ type_tag_name
+
+(*Escaping of special characters.
+  Alphanumeric characters are left unchanged.
+  The character _ goes to __
+  Characters in the range ASCII space to / go to _A to _P, respectively.
+  Other characters go to _nnn where nnn is the decimal ASCII code.*)
+val upper_a_minus_space = Char.ord #"A" - Char.ord #" "
+
+fun stringN_of_int 0 _ = ""
+  | stringN_of_int k n =
+    stringN_of_int (k - 1) (n div 10) ^ string_of_int (n mod 10)
+
+fun ascii_of_char c =
+  if Char.isAlphaNum c then
+    String.str c
+  else if c = #"_" then
+    "__"
+  else if #" " <= c andalso c <= #"/" then
+    "_" ^ String.str (Char.chr (Char.ord c + upper_a_minus_space))
+  else
+    (* fixed width, in case more digits follow *)
+    "_" ^ stringN_of_int 3 (Char.ord c)
+
+val ascii_of = String.translate ascii_of_char
+
+(** Remove ASCII armoring from names in proof files **)
+
+(* We don't raise error exceptions because this code can run inside a worker
+   thread. Also, the errors are impossible. *)
+val unascii_of =
+  let
+    fun un rcs [] = String.implode(rev rcs)
+      | un rcs [#"_"] = un (#"_" :: rcs) [] (* ERROR *)
+        (* Three types of _ escapes: __, _A to _P, _nnn *)
+      | un rcs (#"_" :: #"_" :: cs) = un (#"_" :: rcs) cs
+      | un rcs (#"_" :: c :: cs) =
+        if #"A" <= c andalso c<= #"P" then
+          (* translation of #" " to #"/" *)
+          un (Char.chr (Char.ord c - upper_a_minus_space) :: rcs) cs
+        else
+          let val digits = List.take (c :: cs, 3) handle General.Subscript => [] in
+            case Int.fromString (String.implode digits) of
+              SOME n => un (Char.chr n :: rcs) (List.drop (cs, 2))
+            | NONE => un (c :: #"_" :: rcs) cs (* ERROR *)
+          end
+      | un rcs (c :: cs) = un (c :: rcs) cs
+  in un [] o String.explode end
+
+(* If string s has the prefix s1, return the result of deleting it,
+   un-ASCII'd. *)
+fun unprefix_and_unascii s1 s =
+  if String.isPrefix s1 s then
+    SOME (unascii_of (String.extract (s, size s1, NONE)))
+  else
+    NONE
+
+val proxy_table =
+  [("c_False", (@{const_name False}, (@{thm fFalse_def},
+       ("fFalse", @{const_name ATP.fFalse})))),
+   ("c_True", (@{const_name True}, (@{thm fTrue_def},
+       ("fTrue", @{const_name ATP.fTrue})))),
+   ("c_Not", (@{const_name Not}, (@{thm fNot_def},
+       ("fNot", @{const_name ATP.fNot})))),
+   ("c_conj", (@{const_name conj}, (@{thm fconj_def},
+       ("fconj", @{const_name ATP.fconj})))),
+   ("c_disj", (@{const_name disj}, (@{thm fdisj_def},
+       ("fdisj", @{const_name ATP.fdisj})))),
+   ("c_implies", (@{const_name implies}, (@{thm fimplies_def},
+       ("fimplies", @{const_name ATP.fimplies})))),
+   ("equal", (@{const_name HOL.eq}, (@{thm fequal_def},
+       ("fequal", @{const_name ATP.fequal})))),
+   ("c_All", (@{const_name All}, (@{thm fAll_def},
+       ("fAll", @{const_name ATP.fAll})))),
+   ("c_Ex", (@{const_name Ex}, (@{thm fEx_def},
+       ("fEx", @{const_name ATP.fEx}))))]
+
+val proxify_const = AList.lookup (op =) proxy_table #> Option.map (snd o snd)
+
+(* Readable names for the more common symbolic functions. Do not mess with the
+   table unless you know what you are doing. *)
+val const_trans_table =
+  [(@{type_name Product_Type.prod}, "prod"),
+   (@{type_name Sum_Type.sum}, "sum"),
+   (@{const_name False}, "False"),
+   (@{const_name True}, "True"),
+   (@{const_name Not}, "Not"),
+   (@{const_name conj}, "conj"),
+   (@{const_name disj}, "disj"),
+   (@{const_name implies}, "implies"),
+   (@{const_name HOL.eq}, "equal"),
+   (@{const_name All}, "All"),
+   (@{const_name Ex}, "Ex"),
+   (@{const_name If}, "If"),
+   (@{const_name Set.member}, "member"),
+   (@{const_name Meson.COMBI}, combinator_prefix ^ "I"),
+   (@{const_name Meson.COMBK}, combinator_prefix ^ "K"),
+   (@{const_name Meson.COMBB}, combinator_prefix ^ "B"),
+   (@{const_name Meson.COMBC}, combinator_prefix ^ "C"),
+   (@{const_name Meson.COMBS}, combinator_prefix ^ "S")]
+  |> Symtab.make
+  |> fold (Symtab.update o swap o snd o snd o snd) proxy_table
+
+(* Invert the table of translations between Isabelle and ATPs. *)
+val const_trans_table_inv =
+  const_trans_table |> Symtab.dest |> map swap |> Symtab.make
+val const_trans_table_unprox =
+  Symtab.empty
+  |> fold (fn (_, (isa, (_, (_, atp)))) => Symtab.update (atp, isa)) proxy_table
+
+val invert_const = perhaps (Symtab.lookup const_trans_table_inv)
+val unproxify_const = perhaps (Symtab.lookup const_trans_table_unprox)
+
+fun lookup_const c =
+  case Symtab.lookup const_trans_table c of
+    SOME c' => c'
+  | NONE => ascii_of c
+
+fun ascii_of_indexname (v, 0) = ascii_of v
+  | ascii_of_indexname (v, i) = ascii_of v ^ "_" ^ string_of_int i
+
+fun make_bound_var x = bound_var_prefix ^ ascii_of x
+fun make_all_bound_var x = all_bound_var_prefix ^ ascii_of x
+fun make_exist_bound_var x = exist_bound_var_prefix ^ ascii_of x
+fun make_schematic_var v = schematic_var_prefix ^ ascii_of_indexname v
+fun make_fixed_var x = fixed_var_prefix ^ ascii_of x
+
+fun make_schematic_type_var (x, i) =
+  tvar_prefix ^ (ascii_of_indexname (unprefix "'" x, i))
+fun make_fixed_type_var x = tfree_prefix ^ (ascii_of (unprefix "'" x))
+
+(* "HOL.eq" and choice are mapped to the ATP's equivalents *)
+local
+  val choice_const = (fst o dest_Const o HOLogic.choice_const) Term.dummyT
+  fun default c = const_prefix ^ lookup_const c
+in
+  fun make_fixed_const _ @{const_name HOL.eq} = tptp_old_equal
+    | make_fixed_const (SOME (THF (_, _, THF_With_Choice))) c =
+      if c = choice_const then tptp_choice else default c
+    | make_fixed_const _ c = default c
+end
+
+fun make_fixed_type_const c = type_const_prefix ^ lookup_const c
+
+fun make_type_class clas = class_prefix ^ ascii_of clas
+
+fun new_skolem_var_name_from_const s =
+  let val ss = s |> space_explode Long_Name.separator in
+    nth ss (length ss - 2)
+  end
+
+(* These are either simplified away by "Meson.presimplify" (most of the time) or
+   handled specially via "fFalse", "fTrue", ..., "fequal". *)
+val atp_irrelevant_consts =
+  [@{const_name False}, @{const_name True}, @{const_name Not},
+   @{const_name conj}, @{const_name disj}, @{const_name implies},
+   @{const_name HOL.eq}, @{const_name If}, @{const_name Let}]
+
+val atp_monomorph_bad_consts =
+  atp_irrelevant_consts @
+  (* These are ignored anyway by the relevance filter (unless they appear in
+     higher-order places) but not by the monomorphizer. *)
+  [@{const_name all}, @{const_name "==>"}, @{const_name "=="},
+   @{const_name Trueprop}, @{const_name All}, @{const_name Ex},
+   @{const_name Ex1}, @{const_name Ball}, @{const_name Bex}]
+
+fun add_schematic_const (x as (_, T)) =
+  Monomorph.typ_has_tvars T ? Symtab.insert_list (op =) x
+val add_schematic_consts_of =
+  Term.fold_aterms (fn Const (x as (s, _)) =>
+                       not (member (op =) atp_monomorph_bad_consts s)
+                       ? add_schematic_const x
+                      | _ => I)
+fun atp_schematic_consts_of t = add_schematic_consts_of t Symtab.empty
+
+(** Definitions and functions for FOL clauses and formulas for TPTP **)
+
+(** Isabelle arities **)
+
+type arity_atom = name * name * name list
+
+val type_class = the_single @{sort type}
+
+type arity_clause =
+  {name : string,
+   prem_atoms : arity_atom list,
+   concl_atom : arity_atom}
+
+fun add_prem_atom tvar =
+  fold (fn s => s <> type_class ? cons (`make_type_class s, `I tvar, []))
+
+(* Arity of type constructor "tcon :: (arg1, ..., argN) res" *)
+fun make_axiom_arity_clause (tcons, name, (cls, args)) =
+  let
+    val tvars = map (prefix tvar_prefix o string_of_int) (1 upto length args)
+    val tvars_srts = ListPair.zip (tvars, args)
+  in
+    {name = name,
+     prem_atoms = [] |> fold (uncurry add_prem_atom) tvars_srts,
+     concl_atom = (`make_type_class cls, `make_fixed_type_const tcons,
+                   tvars ~~ tvars)}
+  end
+
+fun arity_clause _ _ (_, []) = []
+  | arity_clause seen n (tcons, ("HOL.type", _) :: ars) =  (* ignore *)
+    arity_clause seen n (tcons, ars)
+  | arity_clause seen n (tcons, (ar as (class, _)) :: ars) =
+    if member (op =) seen class then
+      (* multiple arities for the same (tycon, class) pair *)
+      make_axiom_arity_clause (tcons,
+          lookup_const tcons ^ "___" ^ ascii_of class ^ "_" ^ string_of_int n,
+          ar) ::
+      arity_clause seen (n + 1) (tcons, ars)
+    else
+      make_axiom_arity_clause (tcons, lookup_const tcons ^ "___" ^
+                               ascii_of class, ar) ::
+      arity_clause (class :: seen) n (tcons, ars)
+
+fun multi_arity_clause [] = []
+  | multi_arity_clause ((tcons, ars) :: tc_arlists) =
+    arity_clause [] 1 (tcons, ars) @ multi_arity_clause tc_arlists
+
+(* Generate all pairs (tycon, class, sorts) such that tycon belongs to class in
+   theory thy provided its arguments have the corresponding sorts. *)
+fun type_class_pairs thy tycons classes =
+  let
+    val alg = Sign.classes_of thy
+    fun domain_sorts tycon = Sorts.mg_domain alg tycon o single
+    fun add_class tycon class =
+      cons (class, domain_sorts tycon class)
+      handle Sorts.CLASS_ERROR _ => I
+    fun try_classes tycon = (tycon, fold (add_class tycon) classes [])
+  in map try_classes tycons end
+
+(*Proving one (tycon, class) membership may require proving others, so iterate.*)
+fun iter_type_class_pairs _ _ [] = ([], [])
+  | iter_type_class_pairs thy tycons classes =
+      let
+        fun maybe_insert_class s =
+          (s <> type_class andalso not (member (op =) classes s))
+          ? insert (op =) s
+        val cpairs = type_class_pairs thy tycons classes
+        val newclasses =
+          [] |> fold (fold (fold (fold maybe_insert_class) o snd) o snd) cpairs
+        val (classes', cpairs') = iter_type_class_pairs thy tycons newclasses
+      in (classes' @ classes, union (op =) cpairs' cpairs) end
+
+fun make_arity_clauses thy tycons =
+  iter_type_class_pairs thy tycons ##> multi_arity_clause
+
+
+(** Isabelle class relations **)
+
+type class_rel_clause =
+  {name : string,
+   subclass : name,
+   superclass : name}
+
+(* Generate all pairs (sub, super) such that sub is a proper subclass of super
+   in theory "thy". *)
+fun class_pairs _ [] _ = []
+  | class_pairs thy subs supers =
+      let
+        val class_less = Sorts.class_less (Sign.classes_of thy)
+        fun add_super sub super = class_less (sub, super) ? cons (sub, super)
+        fun add_supers sub = fold (add_super sub) supers
+      in fold add_supers subs [] end
+
+fun make_class_rel_clause (sub, super) =
+  {name = sub ^ "_" ^ super, subclass = `make_type_class sub,
+   superclass = `make_type_class super}
+
+fun make_class_rel_clauses thy subs supers =
+  map make_class_rel_clause (class_pairs thy subs supers)
+
+(* intermediate terms *)
+datatype iterm =
+  IConst of name * typ * typ list |
+  IVar of name * typ |
+  IApp of iterm * iterm |
+  IAbs of (name * typ) * iterm
+
+fun ityp_of (IConst (_, T, _)) = T
+  | ityp_of (IVar (_, T)) = T
+  | ityp_of (IApp (t1, _)) = snd (dest_funT (ityp_of t1))
+  | ityp_of (IAbs ((_, T), tm)) = T --> ityp_of tm
+
+(*gets the head of a combinator application, along with the list of arguments*)
+fun strip_iterm_comb u =
+  let
+    fun stripc (IApp (t, u), ts) = stripc (t, u :: ts)
+      | stripc x = x
+  in stripc (u, []) end
+
+fun atomic_types_of T = fold_atyps (insert (op =)) T []
+
+val tvar_a_str = "'a"
+val tvar_a = TVar ((tvar_a_str, 0), HOLogic.typeS)
+val tvar_a_name = (make_schematic_type_var (tvar_a_str, 0), tvar_a_str)
+val itself_name = `make_fixed_type_const @{type_name itself}
+val TYPE_name = `(make_fixed_const NONE) @{const_name TYPE}
+val tvar_a_atype = AType (tvar_a_name, [])
+val a_itself_atype = AType (itself_name, [tvar_a_atype])
+
+fun new_skolem_const_name s num_T_args =
+  [new_skolem_const_prefix, s, string_of_int num_T_args]
+  |> space_implode Long_Name.separator
+
+fun robust_const_type thy s =
+  if s = app_op_name then
+    Logic.varifyT_global @{typ "('a => 'b) => 'a => 'b"}
+  else if String.isPrefix lam_lifted_prefix s then
+    Logic.varifyT_global @{typ "'a => 'b"}
+  else
+    (* Old Skolems throw a "TYPE" exception here, which will be caught. *)
+    s |> Sign.the_const_type thy
+
+(* This function only makes sense if "T" is as general as possible. *)
+fun robust_const_typargs thy (s, T) =
+  if s = app_op_name then
+    let val (T1, T2) = T |> domain_type |> dest_funT in [T1, T2] end
+  else if String.isPrefix old_skolem_const_prefix s then
+    [] |> Term.add_tvarsT T |> rev |> map TVar
+  else if String.isPrefix lam_lifted_prefix s then
+    if String.isPrefix lam_lifted_poly_prefix s then
+      let val (T1, T2) = T |> dest_funT in [T1, T2] end
+    else
+      []
+  else
+    (s, T) |> Sign.const_typargs thy
+
+(* Converts an Isabelle/HOL term (with combinators) into an intermediate term.
+   Also accumulates sort infomation. *)
+fun iterm_from_term thy format bs (P $ Q) =
+    let
+      val (P', P_atomics_Ts) = iterm_from_term thy format bs P
+      val (Q', Q_atomics_Ts) = iterm_from_term thy format bs Q
+    in (IApp (P', Q'), union (op =) P_atomics_Ts Q_atomics_Ts) end
+  | iterm_from_term thy format _ (Const (c, T)) =
+    (IConst (`(make_fixed_const (SOME format)) c, T,
+             robust_const_typargs thy (c, T)),
+     atomic_types_of T)
+  | iterm_from_term _ _ _ (Free (s, T)) =
+    (IConst (`make_fixed_var s, T, []), atomic_types_of T)
+  | iterm_from_term _ format _ (Var (v as (s, _), T)) =
+    (if String.isPrefix Meson_Clausify.new_skolem_var_prefix s then
+       let
+         val Ts = T |> strip_type |> swap |> op ::
+         val s' = new_skolem_const_name s (length Ts)
+       in IConst (`(make_fixed_const (SOME format)) s', T, Ts) end
+     else
+       IVar ((make_schematic_var v, s), T), atomic_types_of T)
+  | iterm_from_term _ _ bs (Bound j) =
+    nth bs j |> (fn (_, (name, T)) => (IConst (name, T, []), atomic_types_of T))
+  | iterm_from_term thy format bs (Abs (s, T, t)) =
+    let
+      fun vary s = s |> AList.defined (op =) bs s ? vary o Symbol.bump_string
+      val s = vary s
+      val name = `make_bound_var s
+      val (tm, atomic_Ts) = iterm_from_term thy format ((s, (name, T)) :: bs) t
+    in (IAbs ((name, T), tm), union (op =) atomic_Ts (atomic_types_of T)) end
+
+datatype locality =
+  General | Helper | Induction | Intro | Elim | Simp | Local | Assum | Chained
+
+datatype order = First_Order | Higher_Order
+datatype polymorphism = Polymorphic | Raw_Monomorphic | Mangled_Monomorphic
+datatype strictness = Strict | Non_Strict
+datatype granularity = All_Vars | Positively_Naked_Vars | Ghost_Type_Arg_Vars
+datatype type_level =
+  All_Types |
+  Noninf_Nonmono_Types of strictness * granularity |
+  Fin_Nonmono_Types of granularity |
+  Const_Arg_Types |
+  No_Types
+
+datatype type_enc =
+  Simple_Types of order * polymorphism * type_level |
+  Guards of polymorphism * type_level |
+  Tags of polymorphism * type_level
+
+fun is_type_enc_higher_order (Simple_Types (Higher_Order, _, _)) = true
+  | is_type_enc_higher_order _ = false
+
+fun polymorphism_of_type_enc (Simple_Types (_, poly, _)) = poly
+  | polymorphism_of_type_enc (Guards (poly, _)) = poly
+  | polymorphism_of_type_enc (Tags (poly, _)) = poly
+
+fun level_of_type_enc (Simple_Types (_, _, level)) = level
+  | level_of_type_enc (Guards (_, level)) = level
+  | level_of_type_enc (Tags (_, level)) = level
+
+fun granularity_of_type_level (Noninf_Nonmono_Types (_, grain)) = grain
+  | granularity_of_type_level (Fin_Nonmono_Types grain) = grain
+  | granularity_of_type_level _ = All_Vars
+
+fun is_type_level_quasi_sound All_Types = true
+  | is_type_level_quasi_sound (Noninf_Nonmono_Types _) = true
+  | is_type_level_quasi_sound _ = false
+val is_type_enc_quasi_sound = is_type_level_quasi_sound o level_of_type_enc
+
+fun is_type_level_fairly_sound (Fin_Nonmono_Types _) = true
+  | is_type_level_fairly_sound level = is_type_level_quasi_sound level
+val is_type_enc_fairly_sound = is_type_level_fairly_sound o level_of_type_enc
+
+fun is_type_level_monotonicity_based (Noninf_Nonmono_Types _) = true
+  | is_type_level_monotonicity_based (Fin_Nonmono_Types _) = true
+  | is_type_level_monotonicity_based _ = false
+
+(* "_query", "_bang", and "_at" are for the ASCII-challenged Metis and
+   Mirabelle. *)
+val queries = ["?", "_query"]
+val bangs = ["!", "_bang"]
+val ats = ["@", "_at"]
+
+fun try_unsuffixes ss s =
+  fold (fn s' => fn NONE => try (unsuffix s') s | some => some) ss NONE
+
+fun try_nonmono constr suffixes fallback s =
+  case try_unsuffixes suffixes s of
+    SOME s =>
+    (case try_unsuffixes suffixes s of
+       SOME s => (constr Positively_Naked_Vars, s)
+     | NONE =>
+       case try_unsuffixes ats s of
+         SOME s => (constr Ghost_Type_Arg_Vars, s)
+       | NONE => (constr All_Vars, s))
+  | NONE => fallback s
+
+fun type_enc_from_string strictness s =
+  (case try (unprefix "poly_") s of
+     SOME s => (SOME Polymorphic, s)
+   | NONE =>
+     case try (unprefix "raw_mono_") s of
+       SOME s => (SOME Raw_Monomorphic, s)
+     | NONE =>
+       case try (unprefix "mono_") s of
+         SOME s => (SOME Mangled_Monomorphic, s)
+       | NONE => (NONE, s))
+  ||> (pair All_Types
+       |> try_nonmono Fin_Nonmono_Types bangs
+       |> try_nonmono (curry Noninf_Nonmono_Types strictness) queries)
+  |> (fn (poly, (level, core)) =>
+         case (core, (poly, level)) of
+           ("simple", (SOME poly, _)) =>
+           (case (poly, level) of
+              (Polymorphic, All_Types) =>
+              Simple_Types (First_Order, Polymorphic, All_Types)
+            | (Mangled_Monomorphic, _) =>
+              if granularity_of_type_level level = All_Vars then
+                Simple_Types (First_Order, Mangled_Monomorphic, level)
+              else
+                raise Same.SAME
+            | _ => raise Same.SAME)
+         | ("simple_higher", (SOME poly, _)) =>
+           (case (poly, level) of
+              (Polymorphic, All_Types) =>
+              Simple_Types (Higher_Order, Polymorphic, All_Types)
+            | (_, Noninf_Nonmono_Types _) => raise Same.SAME
+            | (Mangled_Monomorphic, _) =>
+              if granularity_of_type_level level = All_Vars then
+                Simple_Types (Higher_Order, Mangled_Monomorphic, level)
+              else
+                raise Same.SAME
+            | _ => raise Same.SAME)
+         | ("guards", (SOME poly, _)) =>
+           if poly = Mangled_Monomorphic andalso
+              granularity_of_type_level level = Ghost_Type_Arg_Vars then
+             raise Same.SAME
+           else
+             Guards (poly, level)
+         | ("tags", (SOME poly, _)) =>
+           if granularity_of_type_level level = Ghost_Type_Arg_Vars then
+             raise Same.SAME
+           else
+             Tags (poly, level)
+         | ("args", (SOME poly, All_Types (* naja *))) =>
+           Guards (poly, Const_Arg_Types)
+         | ("erased", (NONE, All_Types (* naja *))) =>
+           Guards (Polymorphic, No_Types)
+         | _ => raise Same.SAME)
+  handle Same.SAME => error ("Unknown type encoding: " ^ quote s ^ ".")
+
+fun adjust_type_enc (THF (TPTP_Monomorphic, _, _))
+                    (Simple_Types (order, _, level)) =
+    Simple_Types (order, Mangled_Monomorphic, level)
+  | adjust_type_enc (THF _) type_enc = type_enc
+  | adjust_type_enc (TFF (TPTP_Monomorphic, _)) (Simple_Types (_, _, level)) =
+    Simple_Types (First_Order, Mangled_Monomorphic, level)
+  | adjust_type_enc (DFG DFG_Sorted) (Simple_Types (_, _, level)) =
+    Simple_Types (First_Order, Mangled_Monomorphic, level)
+  | adjust_type_enc (TFF _) (Simple_Types (_, poly, level)) =
+    Simple_Types (First_Order, poly, level)
+  | adjust_type_enc format (Simple_Types (_, poly, level)) =
+    adjust_type_enc format (Guards (poly, level))
+  | adjust_type_enc CNF_UEQ (type_enc as Guards stuff) =
+    (if is_type_enc_fairly_sound type_enc then Tags else Guards) stuff
+  | adjust_type_enc _ type_enc = type_enc
+
+fun constify_lifted (t $ u) = constify_lifted t $ constify_lifted u
+  | constify_lifted (Abs (s, T, t)) = Abs (s, T, constify_lifted t)
+  | constify_lifted (Free (x as (s, _))) =
+    (if String.isPrefix lam_lifted_prefix s then Const else Free) x
+  | constify_lifted t = t
+
+(* Requires bound variables not to clash with any schematic variables (as should
+   be the case right after lambda-lifting). *)
+fun open_form (Const (@{const_name All}, _) $ Abs (s, T, t)) =
+    let
+      val names = Name.make_context (map fst (Term.add_var_names t []))
+      val (s, _) = Name.variant s names
+    in open_form (subst_bound (Var ((s, 0), T), t)) end
+  | open_form t = t
+
+fun lift_lams_part_1 ctxt type_enc =
+  map close_form #> rpair ctxt
+  #-> Lambda_Lifting.lift_lambdas
+          (SOME ((if polymorphism_of_type_enc type_enc = Polymorphic then
+                    lam_lifted_poly_prefix
+                  else
+                    lam_lifted_mono_prefix) ^ "_a"))
+          Lambda_Lifting.is_quantifier
+  #> fst
+val lift_lams_part_2 = pairself (map (open_form o constify_lifted))
+val lift_lams = lift_lams_part_2 ooo lift_lams_part_1
+
+fun intentionalize_def (Const (@{const_name All}, _) $ Abs (_, _, t)) =
+    intentionalize_def t
+  | intentionalize_def (Const (@{const_name HOL.eq}, _) $ t $ u) =
+    let
+      fun lam T t = Abs (Name.uu, T, t)
+      val (head, args) = strip_comb t ||> rev
+      val head_T = fastype_of head
+      val n = length args
+      val arg_Ts = head_T |> binder_types |> take n |> rev
+      val u = u |> subst_atomic (args ~~ map Bound (0 upto n - 1))
+    in HOLogic.eq_const head_T $ head $ fold lam arg_Ts u end
+  | intentionalize_def t = t
+
+type translated_formula =
+  {name : string,
+   locality : locality,
+   kind : formula_kind,
+   iformula : (name, typ, iterm) formula,
+   atomic_types : typ list}
+
+fun update_iformula f ({name, locality, kind, iformula, atomic_types}
+                       : translated_formula) =
+  {name = name, locality = locality, kind = kind, iformula = f iformula,
+   atomic_types = atomic_types} : translated_formula
+
+fun fact_lift f ({iformula, ...} : translated_formula) = f iformula
+
+fun insert_type ctxt get_T x xs =
+  let val T = get_T x in
+    if exists (type_instance ctxt T o get_T) xs then xs
+    else x :: filter_out (type_generalization ctxt T o get_T) xs
+  end
+
+(* The Booleans indicate whether all type arguments should be kept. *)
+datatype type_arg_policy =
+  Explicit_Type_Args of bool (* infer_from_term_args *) |
+  Mangled_Type_Args |
+  No_Type_Args
+
+fun type_arg_policy monom_constrs type_enc s =
+  let val poly = polymorphism_of_type_enc type_enc in
+    if s = type_tag_name then
+      if poly = Mangled_Monomorphic then Mangled_Type_Args
+      else Explicit_Type_Args false
+    else case type_enc of
+      Simple_Types (_, Polymorphic, _) => Explicit_Type_Args false
+    | Tags (_, All_Types) => No_Type_Args
+    | _ =>
+      let val level = level_of_type_enc type_enc in
+        if level = No_Types orelse s = @{const_name HOL.eq} orelse
+           (s = app_op_name andalso level = Const_Arg_Types) then
+          No_Type_Args
+        else if poly = Mangled_Monomorphic then
+          Mangled_Type_Args
+        else if member (op =) monom_constrs s andalso
+                granularity_of_type_level level = Positively_Naked_Vars then
+          No_Type_Args
+        else
+          Explicit_Type_Args
+              (level = All_Types orelse
+               granularity_of_type_level level = Ghost_Type_Arg_Vars)
+      end
+  end
+
+(* Make atoms for sorted type variables. *)
+fun generic_add_sorts_on_type (_, []) = I
+  | generic_add_sorts_on_type ((x, i), s :: ss) =
+    generic_add_sorts_on_type ((x, i), ss)
+    #> (if s = the_single @{sort HOL.type} then
+          I
+        else if i = ~1 then
+          insert (op =) (`make_type_class s, `make_fixed_type_var x)
+        else
+          insert (op =) (`make_type_class s,
+                         (make_schematic_type_var (x, i), x)))
+fun add_sorts_on_tfree (TFree (s, S)) = generic_add_sorts_on_type ((s, ~1), S)
+  | add_sorts_on_tfree _ = I
+fun add_sorts_on_tvar (TVar z) = generic_add_sorts_on_type z
+  | add_sorts_on_tvar _ = I
+
+fun type_class_formula type_enc class arg =
+  AAtom (ATerm (class, arg ::
+      (case type_enc of
+         Simple_Types (First_Order, Polymorphic, _) =>
+         if avoid_first_order_ghost_type_vars then [ATerm (TYPE_name, [arg])]
+         else []
+       | _ => [])))
+fun formulas_for_types type_enc add_sorts_on_typ Ts =
+  [] |> level_of_type_enc type_enc <> No_Types ? fold add_sorts_on_typ Ts
+     |> map (fn (class, name) =>
+                type_class_formula type_enc class (ATerm (name, [])))
+
+fun mk_aconns c phis =
+  let val (phis', phi') = split_last phis in
+    fold_rev (mk_aconn c) phis' phi'
+  end
+fun mk_ahorn [] phi = phi
+  | mk_ahorn phis psi = AConn (AImplies, [mk_aconns AAnd phis, psi])
+fun mk_aquant _ [] phi = phi
+  | mk_aquant q xs (phi as AQuant (q', xs', phi')) =
+    if q = q' then AQuant (q, xs @ xs', phi') else AQuant (q, xs, phi)
+  | mk_aquant q xs phi = AQuant (q, xs, phi)
+
+fun close_universally add_term_vars phi =
+  let
+    fun add_formula_vars bounds (AQuant (_, xs, phi)) =
+        add_formula_vars (map fst xs @ bounds) phi
+      | add_formula_vars bounds (AConn (_, phis)) =
+        fold (add_formula_vars bounds) phis
+      | add_formula_vars bounds (AAtom tm) = add_term_vars bounds tm
+  in mk_aquant AForall (add_formula_vars [] phi []) phi end
+
+fun add_term_vars bounds (ATerm (name as (s, _), tms)) =
+    (if is_tptp_variable s andalso
+        not (String.isPrefix tvar_prefix s) andalso
+        not (member (op =) bounds name) then
+       insert (op =) (name, NONE)
+     else
+       I)
+    #> fold (add_term_vars bounds) tms
+  | add_term_vars bounds (AAbs ((name, _), tm)) =
+    add_term_vars (name :: bounds) tm
+fun close_formula_universally phi = close_universally add_term_vars phi
+
+fun add_iterm_vars bounds (IApp (tm1, tm2)) =
+    fold (add_iterm_vars bounds) [tm1, tm2]
+  | add_iterm_vars _ (IConst _) = I
+  | add_iterm_vars bounds (IVar (name, T)) =
+    not (member (op =) bounds name) ? insert (op =) (name, SOME T)
+  | add_iterm_vars bounds (IAbs (_, tm)) = add_iterm_vars bounds tm
+fun close_iformula_universally phi = close_universally add_iterm_vars phi
+
+val fused_infinite_type_name = @{type_name ind} (* any infinite type *)
+val fused_infinite_type = Type (fused_infinite_type_name, [])
+
+fun tvar_name (x as (s, _)) = (make_schematic_type_var x, s)
+
+fun ho_term_from_typ format type_enc =
+  let
+    fun term (Type (s, Ts)) =
+      ATerm (case (is_type_enc_higher_order type_enc, s) of
+               (true, @{type_name bool}) => `I tptp_bool_type
+             | (true, @{type_name fun}) => `I tptp_fun_type
+             | _ => if s = fused_infinite_type_name andalso
+                       is_format_typed format then
+                      `I tptp_individual_type
+                    else
+                      `make_fixed_type_const s,
+             map term Ts)
+    | term (TFree (s, _)) = ATerm (`make_fixed_type_var s, [])
+    | term (TVar (x, _)) = ATerm (tvar_name x, [])
+  in term end
+
+fun ho_term_for_type_arg format type_enc T =
+  if T = dummyT then NONE else SOME (ho_term_from_typ format type_enc T)
+
+(* This shouldn't clash with anything else. *)
+val mangled_type_sep = "\000"
+
+fun generic_mangled_type_name f (ATerm (name, [])) = f name
+  | generic_mangled_type_name f (ATerm (name, tys)) =
+    f name ^ "(" ^ space_implode "," (map (generic_mangled_type_name f) tys)
+    ^ ")"
+  | generic_mangled_type_name _ _ = raise Fail "unexpected type abstraction"
+
+fun mangled_type format type_enc =
+  generic_mangled_type_name fst o ho_term_from_typ format type_enc
+
+fun make_simple_type s =
+  if s = tptp_bool_type orelse s = tptp_fun_type orelse
+     s = tptp_individual_type then
+    s
+  else
+    simple_type_prefix ^ ascii_of s
+
+fun ho_type_from_ho_term type_enc pred_sym ary =
+  let
+    fun to_mangled_atype ty =
+      AType ((make_simple_type (generic_mangled_type_name fst ty),
+              generic_mangled_type_name snd ty), [])
+    fun to_poly_atype (ATerm (name, tys)) = AType (name, map to_poly_atype tys)
+      | to_poly_atype _ = raise Fail "unexpected type abstraction"
+    val to_atype =
+      if polymorphism_of_type_enc type_enc = Polymorphic then to_poly_atype
+      else to_mangled_atype
+    fun to_afun f1 f2 tys = AFun (f1 (hd tys), f2 (nth tys 1))
+    fun to_fo 0 ty = if pred_sym then bool_atype else to_atype ty
+      | to_fo ary (ATerm (_, tys)) = to_afun to_atype (to_fo (ary - 1)) tys
+      | to_fo _ _ = raise Fail "unexpected type abstraction"
+    fun to_ho (ty as ATerm ((s, _), tys)) =
+        if s = tptp_fun_type then to_afun to_ho to_ho tys else to_atype ty
+      | to_ho _ = raise Fail "unexpected type abstraction"
+  in if is_type_enc_higher_order type_enc then to_ho else to_fo ary end
+
+fun ho_type_from_typ format type_enc pred_sym ary =
+  ho_type_from_ho_term type_enc pred_sym ary
+  o ho_term_from_typ format type_enc
+
+fun mangled_const_name format type_enc T_args (s, s') =
+  let
+    val ty_args = T_args |> map_filter (ho_term_for_type_arg format type_enc)
+    fun type_suffix f g =
+      fold_rev (curry (op ^) o g o prefix mangled_type_sep
+                o generic_mangled_type_name f) ty_args ""
+  in (s ^ type_suffix fst ascii_of, s' ^ type_suffix snd I) end
+
+val parse_mangled_ident =
+  Scan.many1 (not o member (op =) ["(", ")", ","]) >> implode
+
+fun parse_mangled_type x =
+  (parse_mangled_ident
+   -- Scan.optional ($$ "(" |-- Scan.optional parse_mangled_types [] --| $$ ")")
+                    [] >> ATerm) x
+and parse_mangled_types x =
+  (parse_mangled_type ::: Scan.repeat ($$ "," |-- parse_mangled_type)) x
+
+fun unmangled_type s =
+  s |> suffix ")" |> raw_explode
+    |> Scan.finite Symbol.stopper
+           (Scan.error (!! (fn _ => raise Fail ("unrecognized mangled type " ^
+                                                quote s)) parse_mangled_type))
+    |> fst
+
+val unmangled_const_name = space_explode mangled_type_sep #> hd
+fun unmangled_const s =
+  let val ss = space_explode mangled_type_sep s in
+    (hd ss, map unmangled_type (tl ss))
+  end
+
+fun introduce_proxies_in_iterm type_enc =
+  let
+    fun tweak_ho_quant ho_quant T [IAbs _] = IConst (`I ho_quant, T, [])
+      | tweak_ho_quant ho_quant (T as Type (_, [p_T as Type (_, [x_T, _]), _]))
+                       _ =
+        (* Eta-expand "!!" and "??", to work around LEO-II 1.2.8 parser
+           limitation. This works in conjuction with special code in
+           "ATP_Problem" that uses the syntactic sugar "!" and "?" whenever
+           possible. *)
+        IAbs ((`I "P", p_T),
+              IApp (IConst (`I ho_quant, T, []),
+                    IAbs ((`I "X", x_T),
+                          IApp (IConst (`I "P", p_T, []),
+                                IConst (`I "X", x_T, [])))))
+      | tweak_ho_quant _ _ _ = raise Fail "unexpected type for quantifier"
+    fun intro top_level args (IApp (tm1, tm2)) =
+        IApp (intro top_level (tm2 :: args) tm1, intro false [] tm2)
+      | intro top_level args (IConst (name as (s, _), T, T_args)) =
+        (case proxify_const s of
+           SOME proxy_base =>
+           if top_level orelse is_type_enc_higher_order type_enc then
+             case (top_level, s) of
+               (_, "c_False") => IConst (`I tptp_false, T, [])
+             | (_, "c_True") => IConst (`I tptp_true, T, [])
+             | (false, "c_Not") => IConst (`I tptp_not, T, [])
+             | (false, "c_conj") => IConst (`I tptp_and, T, [])
+             | (false, "c_disj") => IConst (`I tptp_or, T, [])
+             | (false, "c_implies") => IConst (`I tptp_implies, T, [])
+             | (false, "c_All") => tweak_ho_quant tptp_ho_forall T args
+             | (false, "c_Ex") => tweak_ho_quant tptp_ho_exists T args
+             | (false, s) =>
+               if is_tptp_equal s andalso length args = 2 then
+                 IConst (`I tptp_equal, T, [])
+               else
+                 (* Use a proxy even for partially applied THF0 equality,
+                    because the LEO-II and Satallax parsers complain about not
+                    being able to infer the type of "=". *)
+                 IConst (proxy_base |>> prefix const_prefix, T, T_args)
+             | _ => IConst (name, T, [])
+           else
+             IConst (proxy_base |>> prefix const_prefix, T, T_args)
+          | NONE => if s = tptp_choice then tweak_ho_quant tptp_choice T args
+                    else IConst (name, T, T_args))
+      | intro _ _ (IAbs (bound, tm)) = IAbs (bound, intro false [] tm)
+      | intro _ _ tm = tm
+  in intro true [] end
+
+fun mangle_type_args_in_iterm format type_enc =
+  if polymorphism_of_type_enc type_enc = Mangled_Monomorphic then
+    let
+      fun mangle (IApp (tm1, tm2)) = IApp (mangle tm1, mangle tm2)
+        | mangle (tm as IConst (_, _, [])) = tm
+        | mangle (tm as IConst (name as (s, _), T, T_args)) =
+          (case unprefix_and_unascii const_prefix s of
+             NONE => tm
+           | SOME s'' =>
+             case type_arg_policy [] type_enc (invert_const s'') of
+               Mangled_Type_Args =>
+               IConst (mangled_const_name format type_enc T_args name, T, [])
+             | _ => tm)
+        | mangle (IAbs (bound, tm)) = IAbs (bound, mangle tm)
+        | mangle tm = tm
+    in mangle end
+  else
+    I
+
+fun chop_fun 0 T = ([], T)
+  | chop_fun n (Type (@{type_name fun}, [dom_T, ran_T])) =
+    chop_fun (n - 1) ran_T |>> cons dom_T
+  | chop_fun _ T = ([], T)
+
+fun filter_const_type_args _ _ _ [] = []
+  | filter_const_type_args thy s ary T_args =
+    let
+      val U = robust_const_type thy s
+      val arg_U_vars = fold Term.add_tvarsT (U |> chop_fun ary |> fst) []
+      val U_args = (s, U) |> robust_const_typargs thy
+    in
+      U_args ~~ T_args
+      |> map (fn (U, T) =>
+                 if member (op =) arg_U_vars (dest_TVar U) then dummyT else T)
+    end
+    handle TYPE _ => T_args
+
+fun filter_type_args_in_iterm thy monom_constrs type_enc =
+  let
+    fun filt ary (IApp (tm1, tm2)) = IApp (filt (ary + 1) tm1, filt 0 tm2)
+      | filt _ (tm as IConst (_, _, [])) = tm
+      | filt ary (IConst (name as (s, _), T, T_args)) =
+        (case unprefix_and_unascii const_prefix s of
+           NONE =>
+           (name,
+            if level_of_type_enc type_enc = No_Types orelse s = tptp_choice then
+              []
+            else
+              T_args)
+         | SOME s'' =>
+           let
+             val s'' = invert_const s''
+             fun filter_T_args false = T_args
+               | filter_T_args true = filter_const_type_args thy s'' ary T_args
+           in
+             case type_arg_policy monom_constrs type_enc s'' of
+               Explicit_Type_Args infer_from_term_args =>
+               (name, filter_T_args infer_from_term_args)
+             | No_Type_Args => (name, [])
+             | Mangled_Type_Args => raise Fail "unexpected (un)mangled symbol"
+           end)
+        |> (fn (name, T_args) => IConst (name, T, T_args))
+      | filt _ (IAbs (bound, tm)) = IAbs (bound, filt 0 tm)
+      | filt _ tm = tm
+  in filt 0 end
+
+fun iformula_from_prop ctxt format type_enc eq_as_iff =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    fun do_term bs t atomic_Ts =
+      iterm_from_term thy format bs (Envir.eta_contract t)
+      |>> (introduce_proxies_in_iterm type_enc
+           #> mangle_type_args_in_iterm format type_enc
+           #> AAtom)
+      ||> union (op =) atomic_Ts
+    fun do_quant bs q pos s T t' =
+      let
+        val s = singleton (Name.variant_list (map fst bs)) s
+        val universal = Option.map (q = AExists ? not) pos
+        val name =
+          s |> `(case universal of
+                   SOME true => make_all_bound_var
+                 | SOME false => make_exist_bound_var
+                 | NONE => make_bound_var)
+      in
+        do_formula ((s, (name, T)) :: bs) pos t'
+        #>> mk_aquant q [(name, SOME T)]
+        ##> union (op =) (atomic_types_of T)
+      end
+    and do_conn bs c pos1 t1 pos2 t2 =
+      do_formula bs pos1 t1 ##>> do_formula bs pos2 t2 #>> uncurry (mk_aconn c)
+    and do_formula bs pos t =
+      case t of
+        @{const Trueprop} $ t1 => do_formula bs pos t1
+      | @{const Not} $ t1 => do_formula bs (Option.map not pos) t1 #>> mk_anot
+      | Const (@{const_name All}, _) $ Abs (s, T, t') =>
+        do_quant bs AForall pos s T t'
+      | (t0 as Const (@{const_name All}, _)) $ t1 =>
+        do_formula bs pos (t0 $ eta_expand (map (snd o snd) bs) t1 1)
+      | Const (@{const_name Ex}, _) $ Abs (s, T, t') =>
+        do_quant bs AExists pos s T t'
+      | (t0 as Const (@{const_name Ex}, _)) $ t1 =>
+        do_formula bs pos (t0 $ eta_expand (map (snd o snd) bs) t1 1)
+      | @{const HOL.conj} $ t1 $ t2 => do_conn bs AAnd pos t1 pos t2
+      | @{const HOL.disj} $ t1 $ t2 => do_conn bs AOr pos t1 pos t2
+      | @{const HOL.implies} $ t1 $ t2 =>
+        do_conn bs AImplies (Option.map not pos) t1 pos t2
+      | Const (@{const_name HOL.eq}, Type (_, [@{typ bool}, _])) $ t1 $ t2 =>
+        if eq_as_iff then do_conn bs AIff NONE t1 NONE t2 else do_term bs t
+      | _ => do_term bs t
+  in do_formula [] end
+
+fun presimplify_term ctxt t =
+  t |> exists_Const (member (op =) Meson.presimplified_consts o fst) t
+       ? (Skip_Proof.make_thm (Proof_Context.theory_of ctxt)
+          #> Meson.presimplify
+          #> prop_of)
+
+fun concealed_bound_name j = atp_weak_prefix ^ string_of_int j
+fun conceal_bounds Ts t =
+  subst_bounds (map (Free o apfst concealed_bound_name)
+                    (0 upto length Ts - 1 ~~ Ts), t)
+fun reveal_bounds Ts =
+  subst_atomic (map (fn (j, T) => (Free (concealed_bound_name j, T), Bound j))
+                    (0 upto length Ts - 1 ~~ Ts))
+
+fun is_fun_equality (@{const_name HOL.eq},
+                     Type (_, [Type (@{type_name fun}, _), _])) = true
+  | is_fun_equality _ = false
+
+fun extensionalize_term ctxt t =
+  if exists_Const is_fun_equality t then
+    let val thy = Proof_Context.theory_of ctxt in
+      t |> cterm_of thy |> Meson.extensionalize_conv ctxt
+        |> prop_of |> Logic.dest_equals |> snd
+    end
+  else
+    t
+
+fun simple_translate_lambdas do_lambdas ctxt t =
+  let val thy = Proof_Context.theory_of ctxt in
+    if Meson.is_fol_term thy t then
+      t
+    else
+      let
+        fun trans Ts t =
+          case t of
+            @{const Not} $ t1 => @{const Not} $ trans Ts t1
+          | (t0 as Const (@{const_name All}, _)) $ Abs (s, T, t') =>
+            t0 $ Abs (s, T, trans (T :: Ts) t')
+          | (t0 as Const (@{const_name All}, _)) $ t1 =>
+            trans Ts (t0 $ eta_expand Ts t1 1)
+          | (t0 as Const (@{const_name Ex}, _)) $ Abs (s, T, t') =>
+            t0 $ Abs (s, T, trans (T :: Ts) t')
+          | (t0 as Const (@{const_name Ex}, _)) $ t1 =>
+            trans Ts (t0 $ eta_expand Ts t1 1)
+          | (t0 as @{const HOL.conj}) $ t1 $ t2 =>
+            t0 $ trans Ts t1 $ trans Ts t2
+          | (t0 as @{const HOL.disj}) $ t1 $ t2 =>
+            t0 $ trans Ts t1 $ trans Ts t2
+          | (t0 as @{const HOL.implies}) $ t1 $ t2 =>
+            t0 $ trans Ts t1 $ trans Ts t2
+          | (t0 as Const (@{const_name HOL.eq}, Type (_, [@{typ bool}, _])))
+              $ t1 $ t2 =>
+            t0 $ trans Ts t1 $ trans Ts t2
+          | _ =>
+            if not (exists_subterm (fn Abs _ => true | _ => false) t) then t
+            else t |> Envir.eta_contract |> do_lambdas ctxt Ts
+        val (t, ctxt') = Variable.import_terms true [t] ctxt |>> the_single
+      in t |> trans [] |> singleton (Variable.export_terms ctxt' ctxt) end
+  end
+
+fun do_cheaply_conceal_lambdas Ts (t1 $ t2) =
+    do_cheaply_conceal_lambdas Ts t1
+    $ do_cheaply_conceal_lambdas Ts t2
+  | do_cheaply_conceal_lambdas Ts (Abs (_, T, t)) =
+    Const (lam_lifted_poly_prefix ^ serial_string (),
+           T --> fastype_of1 (T :: Ts, t))
+  | do_cheaply_conceal_lambdas _ t = t
+
+fun do_introduce_combinators ctxt Ts t =
+  let val thy = Proof_Context.theory_of ctxt in
+    t |> conceal_bounds Ts
+      |> cterm_of thy
+      |> Meson_Clausify.introduce_combinators_in_cterm
+      |> prop_of |> Logic.dest_equals |> snd
+      |> reveal_bounds Ts
+  end
+  (* A type variable of sort "{}" will make abstraction fail. *)
+  handle THM _ => t |> do_cheaply_conceal_lambdas Ts
+val introduce_combinators = simple_translate_lambdas do_introduce_combinators
+
+fun preprocess_abstractions_in_terms trans_lams facts =
+  let
+    val (facts, lambda_ts) =
+      facts |> map (snd o snd) |> trans_lams
+            |>> map2 (fn (name, (kind, _)) => fn t => (name, (kind, t))) facts
+    val lam_facts =
+      map2 (fn t => fn j =>
+               ((lam_fact_prefix ^ Int.toString j, Helper), (Axiom, t)))
+           lambda_ts (1 upto length lambda_ts)
+  in (facts, lam_facts) end
+
+(* Metis's use of "resolve_tac" freezes the schematic variables. We simulate the
+   same in Sledgehammer to prevent the discovery of unreplayable proofs. *)
+fun freeze_term t =
+  let
+    fun freeze (t $ u) = freeze t $ freeze u
+      | freeze (Abs (s, T, t)) = Abs (s, T, freeze t)
+      | freeze (Var ((s, i), T)) =
+        Free (atp_weak_prefix ^ s ^ "_" ^ string_of_int i, T)
+      | freeze t = t
+  in t |> exists_subterm is_Var t ? freeze end
+
+fun presimp_prop ctxt role t =
+  (let
+     val thy = Proof_Context.theory_of ctxt
+     val t = t |> Envir.beta_eta_contract
+               |> transform_elim_prop
+               |> Object_Logic.atomize_term thy
+     val need_trueprop = (fastype_of t = @{typ bool})
+   in
+     t |> need_trueprop ? HOLogic.mk_Trueprop
+       |> extensionalize_term ctxt
+       |> presimplify_term ctxt
+       |> HOLogic.dest_Trueprop
+   end
+   handle TERM _ => if role = Conjecture then @{term False} else @{term True})
+  |> pair role
+
+fun make_formula ctxt format type_enc eq_as_iff name loc kind t =
+  let
+    val (iformula, atomic_Ts) =
+      iformula_from_prop ctxt format type_enc eq_as_iff
+                         (SOME (kind <> Conjecture)) t []
+      |>> close_iformula_universally
+  in
+    {name = name, locality = loc, kind = kind, iformula = iformula,
+     atomic_types = atomic_Ts}
+  end
+
+fun make_fact ctxt format type_enc eq_as_iff ((name, loc), t) =
+  case t |> make_formula ctxt format type_enc (eq_as_iff andalso format <> CNF)
+                         name loc Axiom of
+    formula as {iformula = AAtom (IConst ((s, _), _, _)), ...} =>
+    if s = tptp_true then NONE else SOME formula
+  | formula => SOME formula
+
+fun s_not_trueprop (@{const Trueprop} $ t) = @{const Trueprop} $ s_not t
+  | s_not_trueprop t =
+    if fastype_of t = @{typ bool} then s_not t else @{prop False} (* too meta *)
+
+fun make_conjecture ctxt format type_enc =
+  map (fn ((name, loc), (kind, t)) =>
+          t |> kind = Conjecture ? s_not_trueprop
+            |> make_formula ctxt format type_enc (format <> CNF) name loc kind)
+
+(** Finite and infinite type inference **)
+
+fun tvar_footprint thy s ary =
+  (case unprefix_and_unascii const_prefix s of
+     SOME s =>
+     s |> invert_const |> robust_const_type thy |> chop_fun ary |> fst
+       |> map (fn T => Term.add_tvarsT T [] |> map fst)
+   | NONE => [])
+  handle TYPE _ => []
+
+fun ghost_type_args thy s ary =
+  if is_tptp_equal s then
+    0 upto ary - 1
+  else
+    let
+      val footprint = tvar_footprint thy s ary
+      val eq = (s = @{const_name HOL.eq})
+      fun ghosts _ [] = []
+        | ghosts seen ((i, tvars) :: args) =
+          ghosts (union (op =) seen tvars) args
+          |> (eq orelse exists (fn tvar => not (member (op =) seen tvar)) tvars)
+             ? cons i
+    in
+      if forall null footprint then
+        []
+      else
+        0 upto length footprint - 1 ~~ footprint
+        |> sort (rev_order o list_ord Term_Ord.indexname_ord o pairself snd)
+        |> ghosts []
+    end
+
+type monotonicity_info =
+  {maybe_finite_Ts : typ list,
+   surely_finite_Ts : typ list,
+   maybe_infinite_Ts : typ list,
+   surely_infinite_Ts : typ list,
+   maybe_nonmono_Ts : typ list}
+
+(* These types witness that the type classes they belong to allow infinite
+   models and hence that any types with these type classes is monotonic. *)
+val known_infinite_types =
+  [@{typ nat}, HOLogic.intT, HOLogic.realT, @{typ "nat => bool"}]
+
+fun is_type_kind_of_surely_infinite ctxt strictness cached_Ts T =
+  strictness <> Strict andalso is_type_surely_infinite ctxt true cached_Ts T
+
+(* Finite types such as "unit", "bool", "bool * bool", and "bool => bool" are
+   dangerous because their "exhaust" properties can easily lead to unsound ATP
+   proofs. On the other hand, all HOL infinite types can be given the same
+   models in first-order logic (via Löwenheim-Skolem). *)
+
+fun should_encode_type _ (_ : monotonicity_info) All_Types _ = true
+  | should_encode_type ctxt {maybe_finite_Ts, surely_infinite_Ts,
+                             maybe_nonmono_Ts, ...}
+                       (Noninf_Nonmono_Types (strictness, grain)) T =
+    grain = Ghost_Type_Arg_Vars orelse
+    (exists (type_intersect ctxt T) maybe_nonmono_Ts andalso
+     not (exists (type_instance ctxt T) surely_infinite_Ts orelse
+          (not (member (type_equiv ctxt) maybe_finite_Ts T) andalso
+           is_type_kind_of_surely_infinite ctxt strictness surely_infinite_Ts
+                                           T)))
+  | should_encode_type ctxt {surely_finite_Ts, maybe_infinite_Ts,
+                             maybe_nonmono_Ts, ...}
+                       (Fin_Nonmono_Types grain) T =
+    grain = Ghost_Type_Arg_Vars orelse
+    (exists (type_intersect ctxt T) maybe_nonmono_Ts andalso
+     (exists (type_generalization ctxt T) surely_finite_Ts orelse
+      (not (member (type_equiv ctxt) maybe_infinite_Ts T) andalso
+       is_type_surely_finite ctxt T)))
+  | should_encode_type _ _ _ _ = false
+
+fun should_guard_type ctxt mono (Guards (_, level)) should_guard_var T =
+    should_guard_var () andalso should_encode_type ctxt mono level T
+  | should_guard_type _ _ _ _ _ = false
+
+fun is_maybe_universal_var (IConst ((s, _), _, _)) =
+    String.isPrefix bound_var_prefix s orelse
+    String.isPrefix all_bound_var_prefix s
+  | is_maybe_universal_var (IVar _) = true
+  | is_maybe_universal_var _ = false
+
+datatype site =
+  Top_Level of bool option |
+  Eq_Arg of bool option |
+  Elsewhere
+
+fun should_tag_with_type _ _ _ (Top_Level _) _ _ = false
+  | should_tag_with_type ctxt mono (Tags (_, level)) site u T =
+    if granularity_of_type_level level = All_Vars then
+      should_encode_type ctxt mono level T
+    else
+      (case (site, is_maybe_universal_var u) of
+         (Eq_Arg _, true) => should_encode_type ctxt mono level T
+       | _ => false)
+  | should_tag_with_type _ _ _ _ _ _ = false
+
+fun fused_type ctxt mono level =
+  let
+    val should_encode = should_encode_type ctxt mono level
+    fun fuse 0 T = if should_encode T then T else fused_infinite_type
+      | fuse ary (Type (@{type_name fun}, [T1, T2])) =
+        fuse 0 T1 --> fuse (ary - 1) T2
+      | fuse _ _ = raise Fail "expected function type"
+  in fuse end
+
+(** predicators and application operators **)
+
+type sym_info =
+  {pred_sym : bool, min_ary : int, max_ary : int, types : typ list,
+   in_conj : bool}
+
+fun default_sym_tab_entries type_enc =
+  (make_fixed_const NONE @{const_name undefined},
+       {pred_sym = false, min_ary = 0, max_ary = 0, types = [],
+        in_conj = false}) ::
+  ([tptp_false, tptp_true]
+   |> map (rpair {pred_sym = true, min_ary = 0, max_ary = 0, types = [],
+                  in_conj = false})) @
+  ([tptp_equal, tptp_old_equal]
+   |> map (rpair {pred_sym = true, min_ary = 2, max_ary = 2, types = [],
+                  in_conj = false}))
+  |> not (is_type_enc_higher_order type_enc)
+     ? cons (prefixed_predicator_name,
+             {pred_sym = true, min_ary = 1, max_ary = 1, types = [],
+              in_conj = false})
+
+fun sym_table_for_facts ctxt type_enc explicit_apply conjs facts =
+  let
+    fun consider_var_ary const_T var_T max_ary =
+      let
+        fun iter ary T =
+          if ary = max_ary orelse type_instance ctxt var_T T orelse
+             type_instance ctxt T var_T then
+            ary
+          else
+            iter (ary + 1) (range_type T)
+      in iter 0 const_T end
+    fun add_universal_var T (accum as ((bool_vars, fun_var_Ts), sym_tab)) =
+      if explicit_apply = NONE andalso
+         (can dest_funT T orelse T = @{typ bool}) then
+        let
+          val bool_vars' = bool_vars orelse body_type T = @{typ bool}
+          fun repair_min_ary {pred_sym, min_ary, max_ary, types, in_conj} =
+            {pred_sym = pred_sym andalso not bool_vars',
+             min_ary = fold (fn T' => consider_var_ary T' T) types min_ary,
+             max_ary = max_ary, types = types, in_conj = in_conj}
+          val fun_var_Ts' =
+            fun_var_Ts |> can dest_funT T ? insert_type ctxt I T
+        in
+          if bool_vars' = bool_vars andalso
+             pointer_eq (fun_var_Ts', fun_var_Ts) then
+            accum
+          else
+            ((bool_vars', fun_var_Ts'), Symtab.map (K repair_min_ary) sym_tab)
+        end
+      else
+        accum
+    fun add_fact_syms conj_fact =
+      let
+        fun add_iterm_syms top_level tm
+                           (accum as ((bool_vars, fun_var_Ts), sym_tab)) =
+          let val (head, args) = strip_iterm_comb tm in
+            (case head of
+               IConst ((s, _), T, _) =>
+               if String.isPrefix bound_var_prefix s orelse
+                  String.isPrefix all_bound_var_prefix s then
+                 add_universal_var T accum
+               else if String.isPrefix exist_bound_var_prefix s then
+                 accum
+               else
+                 let val ary = length args in
+                   ((bool_vars, fun_var_Ts),
+                    case Symtab.lookup sym_tab s of
+                      SOME {pred_sym, min_ary, max_ary, types, in_conj} =>
+                      let
+                        val pred_sym =
+                          pred_sym andalso top_level andalso not bool_vars
+                        val types' = types |> insert_type ctxt I T
+                        val in_conj = in_conj orelse conj_fact
+                        val min_ary =
+                          if is_some explicit_apply orelse
+                             pointer_eq (types', types) then
+                            min_ary
+                          else
+                            fold (consider_var_ary T) fun_var_Ts min_ary
+                      in
+                        Symtab.update (s, {pred_sym = pred_sym,
+                                           min_ary = Int.min (ary, min_ary),
+                                           max_ary = Int.max (ary, max_ary),
+                                           types = types', in_conj = in_conj})
+                                      sym_tab
+                      end
+                    | NONE =>
+                      let
+                        val pred_sym = top_level andalso not bool_vars
+                        val min_ary =
+                          case explicit_apply of
+                            SOME true => 0
+                          | SOME false => ary
+                          | NONE => fold (consider_var_ary T) fun_var_Ts ary
+                      in
+                        Symtab.update_new (s,
+                            {pred_sym = pred_sym, min_ary = min_ary,
+                             max_ary = ary, types = [T], in_conj = conj_fact})
+                            sym_tab
+                      end)
+                 end
+             | IVar (_, T) => add_universal_var T accum
+             | IAbs ((_, T), tm) =>
+               accum |> add_universal_var T |> add_iterm_syms false tm
+             | _ => accum)
+            |> fold (add_iterm_syms false) args
+          end
+      in K (add_iterm_syms true) |> formula_fold NONE |> fact_lift end
+  in
+    ((false, []), Symtab.empty)
+    |> fold (add_fact_syms true) conjs
+    |> fold (add_fact_syms false) facts
+    |> snd
+    |> fold Symtab.update (default_sym_tab_entries type_enc)
+  end
+
+fun min_ary_of sym_tab s =
+  case Symtab.lookup sym_tab s of
+    SOME ({min_ary, ...} : sym_info) => min_ary
+  | NONE =>
+    case unprefix_and_unascii const_prefix s of
+      SOME s =>
+      let val s = s |> unmangled_const_name |> invert_const in
+        if s = predicator_name then 1
+        else if s = app_op_name then 2
+        else if s = type_guard_name then 1
+        else 0
+      end
+    | NONE => 0
+
+(* True if the constant ever appears outside of the top-level position in
+   literals, or if it appears with different arities (e.g., because of different
+   type instantiations). If false, the constant always receives all of its
+   arguments and is used as a predicate. *)
+fun is_pred_sym sym_tab s =
+  case Symtab.lookup sym_tab s of
+    SOME ({pred_sym, min_ary, max_ary, ...} : sym_info) =>
+    pred_sym andalso min_ary = max_ary
+  | NONE => false
+
+val app_op = `(make_fixed_const NONE) app_op_name
+val predicator_combconst =
+  IConst (`(make_fixed_const NONE) predicator_name, @{typ "bool => bool"}, [])
+
+fun list_app head args = fold (curry (IApp o swap)) args head
+fun predicator tm = IApp (predicator_combconst, tm)
+
+fun firstorderize_fact thy monom_constrs format type_enc sym_tab =
+  let
+    fun do_app arg head =
+      let
+        val head_T = ityp_of head
+        val (arg_T, res_T) = dest_funT head_T
+        val app =
+          IConst (app_op, head_T --> head_T, [arg_T, res_T])
+          |> mangle_type_args_in_iterm format type_enc
+      in list_app app [head, arg] end
+    fun list_app_ops head args = fold do_app args head
+    fun introduce_app_ops tm =
+      case strip_iterm_comb tm of
+        (head as IConst ((s, _), _, _), args) =>
+        args |> map introduce_app_ops
+             |> chop (min_ary_of sym_tab s)
+             |>> list_app head
+             |-> list_app_ops
+      | (head, args) => list_app_ops head (map introduce_app_ops args)
+    fun introduce_predicators tm =
+      case strip_iterm_comb tm of
+        (IConst ((s, _), _, _), _) =>
+        if is_pred_sym sym_tab s then tm else predicator tm
+      | _ => predicator tm
+    val do_iterm =
+      not (is_type_enc_higher_order type_enc)
+      ? (introduce_app_ops #> introduce_predicators)
+      #> filter_type_args_in_iterm thy monom_constrs type_enc
+  in update_iformula (formula_map do_iterm) end
+
+(** Helper facts **)
+
+val not_ffalse = @{lemma "~ fFalse" by (unfold fFalse_def) fast}
+val ftrue = @{lemma "fTrue" by (unfold fTrue_def) fast}
+
+(* The Boolean indicates that a fairly sound type encoding is needed. *)
+val helper_table =
+  [(("COMBI", false), @{thms Meson.COMBI_def}),
+   (("COMBK", false), @{thms Meson.COMBK_def}),
+   (("COMBB", false), @{thms Meson.COMBB_def}),
+   (("COMBC", false), @{thms Meson.COMBC_def}),
+   (("COMBS", false), @{thms Meson.COMBS_def}),
+   ((predicator_name, false), [not_ffalse, ftrue]),
+   (("fFalse", false), [not_ffalse]),
+   (("fFalse", true), @{thms True_or_False}),
+   (("fTrue", false), [ftrue]),
+   (("fTrue", true), @{thms True_or_False}),
+   (("fNot", false),
+    @{thms fNot_def [THEN Meson.iff_to_disjD, THEN conjunct1]
+           fNot_def [THEN Meson.iff_to_disjD, THEN conjunct2]}),
+   (("fconj", false),
+    @{lemma "~ P | ~ Q | fconj P Q" "~ fconj P Q | P" "~ fconj P Q | Q"
+        by (unfold fconj_def) fast+}),
+   (("fdisj", false),
+    @{lemma "~ P | fdisj P Q" "~ Q | fdisj P Q" "~ fdisj P Q | P | Q"
+        by (unfold fdisj_def) fast+}),
+   (("fimplies", false),
+    @{lemma "P | fimplies P Q" "~ Q | fimplies P Q" "~ fimplies P Q | ~ P | Q"
+        by (unfold fimplies_def) fast+}),
+   (("fequal", true),
+    (* This is a lie: Higher-order equality doesn't need a sound type encoding.
+       However, this is done so for backward compatibility: Including the
+       equality helpers by default in Metis breaks a few existing proofs. *)
+    @{thms fequal_def [THEN Meson.iff_to_disjD, THEN conjunct1]
+           fequal_def [THEN Meson.iff_to_disjD, THEN conjunct2]}),
+   (* Partial characterization of "fAll" and "fEx". A complete characterization
+      would require the axiom of choice for replay with Metis. *)
+   (("fAll", false), [@{lemma "~ fAll P | P x" by (auto simp: fAll_def)}]),
+   (("fEx", false), [@{lemma "~ P x | fEx P" by (auto simp: fEx_def)}]),
+   (("If", true), @{thms if_True if_False True_or_False})]
+  |> map (apsnd (map zero_var_indexes))
+
+fun atype_of_type_vars (Simple_Types (_, Polymorphic, _)) = SOME atype_of_types
+  | atype_of_type_vars _ = NONE
+
+fun bound_tvars type_enc sorts Ts =
+  (sorts ? mk_ahorn (formulas_for_types type_enc add_sorts_on_tvar Ts))
+  #> mk_aquant AForall
+        (map_filter (fn TVar (x as (s, _), _) =>
+                        SOME ((make_schematic_type_var x, s),
+                              atype_of_type_vars type_enc)
+                      | _ => NONE) Ts)
+
+fun eq_formula type_enc atomic_Ts pred_sym tm1 tm2 =
+  (if pred_sym then AConn (AIff, [AAtom tm1, AAtom tm2])
+   else AAtom (ATerm (`I tptp_equal, [tm1, tm2])))
+  |> close_formula_universally
+  |> bound_tvars type_enc true atomic_Ts
+
+val type_tag = `(make_fixed_const NONE) type_tag_name
+
+fun type_tag_idempotence_fact format type_enc =
+  let
+    fun var s = ATerm (`I s, [])
+    fun tag tm = ATerm (type_tag, [var "A", tm])
+    val tagged_var = tag (var "X")
+  in
+    Formula (type_tag_idempotence_helper_name, Axiom,
+             eq_formula type_enc [] false (tag tagged_var) tagged_var,
+             isabelle_info format simpN, NONE)
+  end
+
+fun should_specialize_helper type_enc t =
+  polymorphism_of_type_enc type_enc <> Polymorphic andalso
+  level_of_type_enc type_enc <> No_Types andalso
+  not (null (Term.hidden_polymorphism t))
+
+fun helper_facts_for_sym ctxt format type_enc (s, {types, ...} : sym_info) =
+  case unprefix_and_unascii const_prefix s of
+    SOME mangled_s =>
+    let
+      val thy = Proof_Context.theory_of ctxt
+      val unmangled_s = mangled_s |> unmangled_const_name
+      fun dub needs_fairly_sound j k =
+        (unmangled_s ^ "_" ^ string_of_int j ^ "_" ^ string_of_int k ^
+         (if mangled_s = unmangled_s then "" else "_" ^ ascii_of mangled_s) ^
+         (if needs_fairly_sound then typed_helper_suffix
+          else untyped_helper_suffix),
+         Helper)
+      fun dub_and_inst needs_fairly_sound (th, j) =
+        let val t = prop_of th in
+          if should_specialize_helper type_enc t then
+            map (fn T => specialize_type thy (invert_const unmangled_s, T) t)
+                types
+          else
+            [t]
+        end
+        |> map (fn (k, t) => (dub needs_fairly_sound j k, t)) o tag_list 1
+      val make_facts = map_filter (make_fact ctxt format type_enc false)
+      val fairly_sound = is_type_enc_fairly_sound type_enc
+    in
+      helper_table
+      |> maps (fn ((helper_s, needs_fairly_sound), ths) =>
+                  if helper_s <> unmangled_s orelse
+                     (needs_fairly_sound andalso not fairly_sound) then
+                    []
+                  else
+                    ths ~~ (1 upto length ths)
+                    |> maps (dub_and_inst needs_fairly_sound)
+                    |> make_facts)
+    end
+  | NONE => []
+fun helper_facts_for_sym_table ctxt format type_enc sym_tab =
+  Symtab.fold_rev (append o helper_facts_for_sym ctxt format type_enc) sym_tab
+                  []
+
+(***************************************************************)
+(* Type Classes Present in the Axiom or Conjecture Clauses     *)
+(***************************************************************)
+
+fun set_insert (x, s) = Symtab.update (x, ()) s
+
+fun add_classes (sorts, cset) = List.foldl set_insert cset (flat sorts)
+
+(* Remove this trivial type class (FIXME: similar code elsewhere) *)
+fun delete_type cset = Symtab.delete_safe (the_single @{sort HOL.type}) cset
+
+fun classes_of_terms get_Ts =
+  map (map snd o get_Ts)
+  #> List.foldl add_classes Symtab.empty
+  #> delete_type #> Symtab.keys
+
+val tfree_classes_of_terms = classes_of_terms Misc_Legacy.term_tfrees
+val tvar_classes_of_terms = classes_of_terms Misc_Legacy.term_tvars
+
+fun fold_type_constrs f (Type (s, Ts)) x =
+    fold (fold_type_constrs f) Ts (f (s, x))
+  | fold_type_constrs _ _ x = x
+
+(* Type constructors used to instantiate overloaded constants are the only ones
+   needed. *)
+fun add_type_constrs_in_term thy =
+  let
+    fun add (Const (@{const_name Meson.skolem}, _) $ _) = I
+      | add (t $ u) = add t #> add u
+      | add (Const x) =
+        x |> robust_const_typargs thy |> fold (fold_type_constrs set_insert)
+      | add (Abs (_, _, u)) = add u
+      | add _ = I
+  in add end
+
+fun type_constrs_of_terms thy ts =
+  Symtab.keys (fold (add_type_constrs_in_term thy) ts Symtab.empty)
+
+fun extract_lambda_def (Const (@{const_name HOL.eq}, _) $ t $ u) =
+    let val (head, args) = strip_comb t in
+      (head |> dest_Const |> fst,
+       fold_rev (fn t as Var ((s, _), T) =>
+                    (fn u => Abs (s, T, abstract_over (t, u)))
+                  | _ => raise Fail "expected Var") args u)
+    end
+  | extract_lambda_def _ = raise Fail "malformed lifted lambda"
+
+fun trans_lams_from_string ctxt type_enc lam_trans =
+  if lam_trans = no_lamsN then
+    rpair []
+  else if lam_trans = hide_lamsN then
+    lift_lams ctxt type_enc ##> K []
+  else if lam_trans = lam_liftingN then
+    lift_lams ctxt type_enc
+  else if lam_trans = combinatorsN then
+    map (introduce_combinators ctxt) #> rpair []
+  else if lam_trans = hybrid_lamsN then
+    lift_lams_part_1 ctxt type_enc
+    ##> maps (fn t => [t, introduce_combinators ctxt (intentionalize_def t)])
+    #> lift_lams_part_2
+  else if lam_trans = keep_lamsN then
+    map (Envir.eta_contract) #> rpair []
+  else
+    error ("Unknown lambda translation scheme: " ^ quote lam_trans ^ ".")
+
+fun translate_formulas ctxt format prem_kind type_enc lam_trans presimp hyp_ts
+                       concl_t facts =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val trans_lams = trans_lams_from_string ctxt type_enc lam_trans
+    val fact_ts = facts |> map snd
+    (* Remove existing facts from the conjecture, as this can dramatically
+       boost an ATP's performance (for some reason). *)
+    val hyp_ts =
+      hyp_ts
+      |> map (fn t => if member (op aconv) fact_ts t then @{prop True} else t)
+    val facts = facts |> map (apsnd (pair Axiom))
+    val conjs =
+      map (pair prem_kind) hyp_ts @ [(Conjecture, s_not_trueprop concl_t)]
+      |> map (apsnd freeze_term)
+      |> map2 (pair o rpair Local o string_of_int) (0 upto length hyp_ts)
+    val ((conjs, facts), lam_facts) =
+      (conjs, facts)
+      |> presimp ? pairself (map (apsnd (uncurry (presimp_prop ctxt))))
+      |> (if lam_trans = no_lamsN then
+            rpair []
+          else
+            op @
+            #> preprocess_abstractions_in_terms trans_lams
+            #>> chop (length conjs))
+    val conjs = conjs |> make_conjecture ctxt format type_enc
+    val (fact_names, facts) =
+      facts
+      |> map_filter (fn (name, (_, t)) =>
+                        make_fact ctxt format type_enc true (name, t)
+                        |> Option.map (pair name))
+      |> ListPair.unzip
+    val lifted = lam_facts |> map (extract_lambda_def o snd o snd)
+    val lam_facts =
+      lam_facts |> map_filter (make_fact ctxt format type_enc true o apsnd snd)
+    val all_ts = concl_t :: hyp_ts @ fact_ts
+    val subs = tfree_classes_of_terms all_ts
+    val supers = tvar_classes_of_terms all_ts
+    val tycons = type_constrs_of_terms thy all_ts
+    val (supers, arity_clauses) =
+      if level_of_type_enc type_enc = No_Types then ([], [])
+      else make_arity_clauses thy tycons supers
+    val class_rel_clauses = make_class_rel_clauses thy subs supers
+  in
+    (fact_names |> map single, union (op =) subs supers, conjs,
+     facts @ lam_facts, class_rel_clauses, arity_clauses, lifted)
+  end
+
+val type_guard = `(make_fixed_const NONE) type_guard_name
+
+fun type_guard_iterm format type_enc T tm =
+  IApp (IConst (type_guard, T --> @{typ bool}, [T])
+        |> mangle_type_args_in_iterm format type_enc, tm)
+
+fun is_var_positively_naked_in_term _ (SOME false) _ accum = accum
+  | is_var_positively_naked_in_term name _ (ATerm ((s, _), tms)) accum =
+    accum orelse (is_tptp_equal s andalso member (op =) tms (ATerm (name, [])))
+  | is_var_positively_naked_in_term _ _ _ _ = true
+
+fun is_var_ghost_type_arg_in_term thy polym_constrs name pos tm accum =
+  is_var_positively_naked_in_term name pos tm accum orelse
+  let
+    val var = ATerm (name, [])
+    fun is_nasty_in_term (ATerm (_, [])) = false
+      | is_nasty_in_term (ATerm ((s, _), tms)) =
+        let
+          val ary = length tms
+          val polym_constr = member (op =) polym_constrs s
+          val ghosts = ghost_type_args thy s ary
+        in
+          exists (fn (j, tm) =>
+                     if polym_constr then
+                       member (op =) ghosts j andalso
+                       (tm = var orelse is_nasty_in_term tm)
+                     else
+                       tm = var andalso member (op =) ghosts j)
+                 (0 upto ary - 1 ~~ tms)
+          orelse (not polym_constr andalso exists is_nasty_in_term tms)
+        end
+      | is_nasty_in_term _ = true
+  in is_nasty_in_term tm end
+
+fun should_guard_var_in_formula thy polym_constrs level pos phi (SOME true)
+                                name =
+    (case granularity_of_type_level level of
+       All_Vars => true
+     | Positively_Naked_Vars =>
+       formula_fold pos (is_var_positively_naked_in_term name) phi false
+     | Ghost_Type_Arg_Vars =>
+       formula_fold pos (is_var_ghost_type_arg_in_term thy polym_constrs name)
+                    phi false)
+  | should_guard_var_in_formula _ _ _ _ _ _ _ = true
+
+fun always_guard_var_in_formula _ _ _ _ _ _ _ = true
+
+fun should_generate_tag_bound_decl _ _ _ (SOME true) _ = false
+  | should_generate_tag_bound_decl ctxt mono (Tags (_, level)) _ T =
+    granularity_of_type_level level <> All_Vars andalso
+    should_encode_type ctxt mono level T
+  | should_generate_tag_bound_decl _ _ _ _ _ = false
+
+fun mk_aterm format type_enc name T_args args =
+  ATerm (name, map_filter (ho_term_for_type_arg format type_enc) T_args @ args)
+
+fun tag_with_type ctxt format mono type_enc pos T tm =
+  IConst (type_tag, T --> T, [T])
+  |> mangle_type_args_in_iterm format type_enc
+  |> ho_term_from_iterm ctxt format mono type_enc pos
+  |> (fn ATerm (s, tms) => ATerm (s, tms @ [tm])
+       | _ => raise Fail "unexpected lambda-abstraction")
+and ho_term_from_iterm ctxt format mono type_enc =
+  let
+    fun term site u =
+      let
+        val (head, args) = strip_iterm_comb u
+        val pos =
+          case site of
+            Top_Level pos => pos
+          | Eq_Arg pos => pos
+          | _ => NONE
+        val t =
+          case head of
+            IConst (name as (s, _), _, T_args) =>
+            let
+              val arg_site = if is_tptp_equal s then Eq_Arg pos else Elsewhere
+            in
+              map (term arg_site) args |> mk_aterm format type_enc name T_args
+            end
+          | IVar (name, _) =>
+            map (term Elsewhere) args |> mk_aterm format type_enc name []
+          | IAbs ((name, T), tm) =>
+            AAbs ((name, ho_type_from_typ format type_enc true 0 T),
+                  term Elsewhere tm)
+          | IApp _ => raise Fail "impossible \"IApp\""
+        val T = ityp_of u
+      in
+        if should_tag_with_type ctxt mono type_enc site u T then
+          tag_with_type ctxt format mono type_enc pos T t
+        else
+          t
+      end
+  in term o Top_Level end
+and formula_from_iformula ctxt polym_constrs format mono type_enc
+                          should_guard_var =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val level = level_of_type_enc type_enc
+    val do_term = ho_term_from_iterm ctxt format mono type_enc
+    val do_bound_type =
+      case type_enc of
+        Simple_Types _ => fused_type ctxt mono level 0
+        #> ho_type_from_typ format type_enc false 0 #> SOME
+      | _ => K NONE
+    fun do_out_of_bound_type pos phi universal (name, T) =
+      if should_guard_type ctxt mono type_enc
+             (fn () => should_guard_var thy polym_constrs level pos phi
+                                        universal name) T then
+        IVar (name, T)
+        |> type_guard_iterm format type_enc T
+        |> do_term pos |> AAtom |> SOME
+      else if should_generate_tag_bound_decl ctxt mono type_enc universal T then
+        let
+          val var = ATerm (name, [])
+          val tagged_var = tag_with_type ctxt format mono type_enc pos T var
+        in SOME (AAtom (ATerm (`I tptp_equal, [tagged_var, var]))) end
+      else
+        NONE
+    fun do_formula pos (AQuant (q, xs, phi)) =
+        let
+          val phi = phi |> do_formula pos
+          val universal = Option.map (q = AExists ? not) pos
+        in
+          AQuant (q, xs |> map (apsnd (fn NONE => NONE
+                                        | SOME T => do_bound_type T)),
+                  (if q = AForall then mk_ahorn else fold_rev (mk_aconn AAnd))
+                      (map_filter
+                           (fn (_, NONE) => NONE
+                             | (s, SOME T) =>
+                               do_out_of_bound_type pos phi universal (s, T))
+                           xs)
+                      phi)
+        end
+      | do_formula pos (AConn conn) = aconn_map pos do_formula conn
+      | do_formula pos (AAtom tm) = AAtom (do_term pos tm)
+  in do_formula end
+
+(* Each fact is given a unique fact number to avoid name clashes (e.g., because
+   of monomorphization). The TPTP explicitly forbids name clashes, and some of
+   the remote provers might care. *)
+fun formula_line_for_fact ctxt polym_constrs format prefix encode freshen pos
+        mono type_enc (j, {name, locality, kind, iformula, atomic_types}) =
+  (prefix ^ (if freshen then string_of_int j ^ "_" else "") ^ encode name, kind,
+   iformula
+   |> formula_from_iformula ctxt polym_constrs format mono type_enc
+          should_guard_var_in_formula (if pos then SOME true else NONE)
+   |> close_formula_universally
+   |> bound_tvars type_enc true atomic_types,
+   NONE,
+   case locality of
+     Intro => isabelle_info format introN
+   | Elim => isabelle_info format elimN
+   | Simp => isabelle_info format simpN
+   | _ => NONE)
+  |> Formula
+
+fun formula_line_for_class_rel_clause format type_enc
+        ({name, subclass, superclass, ...} : class_rel_clause) =
+  let val ty_arg = ATerm (tvar_a_name, []) in
+    Formula (class_rel_clause_prefix ^ ascii_of name, Axiom,
+             AConn (AImplies,
+                    [type_class_formula type_enc subclass ty_arg,
+                     type_class_formula type_enc superclass ty_arg])
+             |> mk_aquant AForall
+                          [(tvar_a_name, atype_of_type_vars type_enc)],
+             isabelle_info format introN, NONE)
+  end
+
+fun formula_from_arity_atom type_enc (class, t, args) =
+  ATerm (t, map (fn arg => ATerm (arg, [])) args)
+  |> type_class_formula type_enc class
+
+fun formula_line_for_arity_clause format type_enc
+        ({name, prem_atoms, concl_atom} : arity_clause) =
+  Formula (arity_clause_prefix ^ name, Axiom,
+           mk_ahorn (map (formula_from_arity_atom type_enc) prem_atoms)
+                    (formula_from_arity_atom type_enc concl_atom)
+           |> mk_aquant AForall
+                  (map (rpair (atype_of_type_vars type_enc)) (#3 concl_atom)),
+           isabelle_info format introN, NONE)
+
+fun formula_line_for_conjecture ctxt polym_constrs format mono type_enc
+        ({name, kind, iformula, atomic_types, ...} : translated_formula) =
+  Formula (conjecture_prefix ^ name, kind,
+           iformula
+           |> formula_from_iformula ctxt polym_constrs format mono type_enc
+                  should_guard_var_in_formula (SOME false)
+           |> close_formula_universally
+           |> bound_tvars type_enc true atomic_types, NONE, NONE)
+
+fun formula_line_for_free_type j phi =
+  Formula (tfree_clause_prefix ^ string_of_int j, Hypothesis, phi, NONE, NONE)
+fun formula_lines_for_free_types type_enc (facts : translated_formula list) =
+  let
+    val phis =
+      fold (union (op =)) (map #atomic_types facts) []
+      |> formulas_for_types type_enc add_sorts_on_tfree
+  in map2 formula_line_for_free_type (0 upto length phis - 1) phis end
+
+(** Symbol declarations **)
+
+fun decl_line_for_class order s =
+  let val name as (s, _) = `make_type_class s in
+    Decl (sym_decl_prefix ^ s, name,
+          if order = First_Order then
+            ATyAbs ([tvar_a_name],
+                    if avoid_first_order_ghost_type_vars then
+                      AFun (a_itself_atype, bool_atype)
+                    else
+                      bool_atype)
+          else
+            AFun (atype_of_types, bool_atype))
+  end
+
+fun decl_lines_for_classes type_enc classes =
+  case type_enc of
+    Simple_Types (order, Polymorphic, _) =>
+    map (decl_line_for_class order) classes
+  | _ => []
+
+fun sym_decl_table_for_facts ctxt format type_enc sym_tab (conjs, facts) =
+  let
+    fun add_iterm_syms tm =
+      let val (head, args) = strip_iterm_comb tm in
+        (case head of
+           IConst ((s, s'), T, T_args) =>
+           let
+             val (pred_sym, in_conj) =
+               case Symtab.lookup sym_tab s of
+                 SOME ({pred_sym, in_conj, ...} : sym_info) =>
+                 (pred_sym, in_conj)
+               | NONE => (false, false)
+             val decl_sym =
+               (case type_enc of
+                  Guards _ => not pred_sym
+                | _ => true) andalso
+               is_tptp_user_symbol s
+           in
+             if decl_sym then
+               Symtab.map_default (s, [])
+                   (insert_type ctxt #3 (s', T_args, T, pred_sym, length args,
+                                         in_conj))
+             else
+               I
+           end
+         | IAbs (_, tm) => add_iterm_syms tm
+         | _ => I)
+        #> fold add_iterm_syms args
+      end
+    val add_fact_syms = K add_iterm_syms |> formula_fold NONE |> fact_lift
+    fun add_formula_var_types (AQuant (_, xs, phi)) =
+        fold (fn (_, SOME T) => insert_type ctxt I T | _ => I) xs
+        #> add_formula_var_types phi
+      | add_formula_var_types (AConn (_, phis)) =
+        fold add_formula_var_types phis
+      | add_formula_var_types _ = I
+    fun var_types () =
+      if polymorphism_of_type_enc type_enc = Polymorphic then [tvar_a]
+      else fold (fact_lift add_formula_var_types) (conjs @ facts) []
+    fun add_undefined_const T =
+      let
+        val (s, s') =
+          `(make_fixed_const NONE) @{const_name undefined}
+          |> (case type_arg_policy [] type_enc @{const_name undefined} of
+                Mangled_Type_Args => mangled_const_name format type_enc [T]
+              | _ => I)
+      in
+        Symtab.map_default (s, [])
+                           (insert_type ctxt #3 (s', [T], T, false, 0, false))
+      end
+    fun add_TYPE_const () =
+      let val (s, s') = TYPE_name in
+        Symtab.map_default (s, [])
+            (insert_type ctxt #3
+                         (s', [tvar_a], @{typ "'a itself"}, false, 0, false))
+      end
+  in
+    Symtab.empty
+    |> is_type_enc_fairly_sound type_enc
+       ? (fold (fold add_fact_syms) [conjs, facts]
+          #> (case type_enc of
+                Simple_Types (First_Order, Polymorphic, _) =>
+                if avoid_first_order_ghost_type_vars then add_TYPE_const ()
+                else I
+              | Simple_Types _ => I
+              | _ => fold add_undefined_const (var_types ())))
+  end
+
+(* We add "bool" in case the helper "True_or_False" is included later. *)
+fun default_mono level =
+  {maybe_finite_Ts = [@{typ bool}],
+   surely_finite_Ts = [@{typ bool}],
+   maybe_infinite_Ts = known_infinite_types,
+   surely_infinite_Ts =
+     case level of
+       Noninf_Nonmono_Types (Strict, _) => []
+     | _ => known_infinite_types,
+   maybe_nonmono_Ts = [@{typ bool}]}
+
+(* This inference is described in section 2.3 of Claessen et al.'s "Sorting it
+   out with monotonicity" paper presented at CADE 2011. *)
+fun add_iterm_mononotonicity_info _ _ (SOME false) _ mono = mono
+  | add_iterm_mononotonicity_info ctxt level _
+        (IApp (IApp (IConst ((s, _), Type (_, [T, _]), _), tm1), tm2))
+        (mono as {maybe_finite_Ts, surely_finite_Ts, maybe_infinite_Ts,
+                  surely_infinite_Ts, maybe_nonmono_Ts}) =
+    if is_tptp_equal s andalso exists is_maybe_universal_var [tm1, tm2] then
+      case level of
+        Noninf_Nonmono_Types (strictness, _) =>
+        if exists (type_instance ctxt T) surely_infinite_Ts orelse
+           member (type_equiv ctxt) maybe_finite_Ts T then
+          mono
+        else if is_type_kind_of_surely_infinite ctxt strictness
+                                                surely_infinite_Ts T then
+          {maybe_finite_Ts = maybe_finite_Ts,
+           surely_finite_Ts = surely_finite_Ts,
+           maybe_infinite_Ts = maybe_infinite_Ts,
+           surely_infinite_Ts = surely_infinite_Ts |> insert_type ctxt I T,
+           maybe_nonmono_Ts = maybe_nonmono_Ts}
+        else
+          {maybe_finite_Ts = maybe_finite_Ts |> insert (type_equiv ctxt) T,
+           surely_finite_Ts = surely_finite_Ts,
+           maybe_infinite_Ts = maybe_infinite_Ts,
+           surely_infinite_Ts = surely_infinite_Ts,
+           maybe_nonmono_Ts = maybe_nonmono_Ts |> insert_type ctxt I T}
+      | Fin_Nonmono_Types _ =>
+        if exists (type_instance ctxt T) surely_finite_Ts orelse
+           member (type_equiv ctxt) maybe_infinite_Ts T then
+          mono
+        else if is_type_surely_finite ctxt T then
+          {maybe_finite_Ts = maybe_finite_Ts,
+           surely_finite_Ts = surely_finite_Ts |> insert_type ctxt I T,
+           maybe_infinite_Ts = maybe_infinite_Ts,
+           surely_infinite_Ts = surely_infinite_Ts,
+           maybe_nonmono_Ts = maybe_nonmono_Ts |> insert_type ctxt I T}
+        else
+          {maybe_finite_Ts = maybe_finite_Ts,
+           surely_finite_Ts = surely_finite_Ts,
+           maybe_infinite_Ts = maybe_infinite_Ts |> insert (type_equiv ctxt) T,
+           surely_infinite_Ts = surely_infinite_Ts,
+           maybe_nonmono_Ts = maybe_nonmono_Ts}
+      | _ => mono
+    else
+      mono
+  | add_iterm_mononotonicity_info _ _ _ _ mono = mono
+fun add_fact_mononotonicity_info ctxt level
+        ({kind, iformula, ...} : translated_formula) =
+  formula_fold (SOME (kind <> Conjecture))
+               (add_iterm_mononotonicity_info ctxt level) iformula
+fun mononotonicity_info_for_facts ctxt type_enc facts =
+  let val level = level_of_type_enc type_enc in
+    default_mono level
+    |> is_type_level_monotonicity_based level
+       ? fold (add_fact_mononotonicity_info ctxt level) facts
+  end
+
+fun add_iformula_monotonic_types ctxt mono type_enc =
+  let
+    val level = level_of_type_enc type_enc
+    val should_encode = should_encode_type ctxt mono level
+    fun add_type T = not (should_encode T) ? insert_type ctxt I T
+    fun add_args (IApp (tm1, tm2)) = add_args tm1 #> add_term tm2
+      | add_args _ = I
+    and add_term tm = add_type (ityp_of tm) #> add_args tm
+  in formula_fold NONE (K add_term) end
+fun add_fact_monotonic_types ctxt mono type_enc =
+  add_iformula_monotonic_types ctxt mono type_enc |> fact_lift
+fun monotonic_types_for_facts ctxt mono type_enc facts =
+  let val level = level_of_type_enc type_enc in
+    [] |> (polymorphism_of_type_enc type_enc = Polymorphic andalso
+           is_type_level_monotonicity_based level andalso
+           granularity_of_type_level level <> Ghost_Type_Arg_Vars)
+          ? fold (add_fact_monotonic_types ctxt mono type_enc) facts
+  end
+
+fun formula_line_for_guards_mono_type ctxt format mono type_enc T =
+  Formula (guards_sym_formula_prefix ^
+           ascii_of (mangled_type format type_enc T),
+           Axiom,
+           IConst (`make_bound_var "X", T, [])
+           |> type_guard_iterm format type_enc T
+           |> AAtom
+           |> formula_from_iformula ctxt [] format mono type_enc
+                                    always_guard_var_in_formula (SOME true)
+           |> close_formula_universally
+           |> bound_tvars type_enc true (atomic_types_of T),
+           isabelle_info format introN, NONE)
+
+fun formula_line_for_tags_mono_type ctxt format mono type_enc T =
+  let val x_var = ATerm (`make_bound_var "X", []) in
+    Formula (tags_sym_formula_prefix ^
+             ascii_of (mangled_type format type_enc T),
+             Axiom,
+             eq_formula type_enc (atomic_types_of T) false
+                  (tag_with_type ctxt format mono type_enc NONE T x_var) x_var,
+             isabelle_info format simpN, NONE)
+  end
+
+fun problem_lines_for_mono_types ctxt format mono type_enc Ts =
+  case type_enc of
+    Simple_Types _ => []
+  | Guards _ =>
+    map (formula_line_for_guards_mono_type ctxt format mono type_enc) Ts
+  | Tags _ => map (formula_line_for_tags_mono_type ctxt format mono type_enc) Ts
+
+fun decl_line_for_sym ctxt format mono type_enc s
+                      (s', T_args, T, pred_sym, ary, _) =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val (T, T_args) =
+      if null T_args then
+        (T, [])
+      else case unprefix_and_unascii const_prefix s of
+        SOME s' =>
+        let
+          val s' = s' |> invert_const
+          val T = s' |> robust_const_type thy
+        in (T, robust_const_typargs thy (s', T)) end
+      | NONE => raise Fail "unexpected type arguments"
+  in
+    Decl (sym_decl_prefix ^ s, (s, s'),
+          T |> fused_type ctxt mono (level_of_type_enc type_enc) ary
+            |> ho_type_from_typ format type_enc pred_sym ary
+            |> not (null T_args)
+               ? curry ATyAbs (map (tvar_name o fst o dest_TVar) T_args))
+  end
+
+fun formula_line_for_guards_sym_decl ctxt format conj_sym_kind mono type_enc n s
+                                     j (s', T_args, T, _, ary, in_conj) =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val (kind, maybe_negate) =
+      if in_conj then (conj_sym_kind, conj_sym_kind = Conjecture ? mk_anot)
+      else (Axiom, I)
+    val (arg_Ts, res_T) = chop_fun ary T
+    val bound_names = 1 upto ary |> map (`I o make_bound_var o string_of_int)
+    val bounds =
+      bound_names ~~ arg_Ts |> map (fn (name, T) => IConst (name, T, []))
+    val bound_Ts =
+      if exists (curry (op =) dummyT) T_args then
+        case level_of_type_enc type_enc of
+          All_Types => map SOME arg_Ts
+        | level =>
+          if granularity_of_type_level level = Ghost_Type_Arg_Vars then
+            let val ghosts = ghost_type_args thy s ary in
+              map2 (fn j => if member (op =) ghosts j then SOME else K NONE)
+                   (0 upto ary - 1) arg_Ts
+            end
+          else
+            replicate ary NONE
+      else
+        replicate ary NONE
+  in
+    Formula (guards_sym_formula_prefix ^ s ^
+             (if n > 1 then "_" ^ string_of_int j else ""), kind,
+             IConst ((s, s'), T, T_args)
+             |> fold (curry (IApp o swap)) bounds
+             |> type_guard_iterm format type_enc res_T
+             |> AAtom |> mk_aquant AForall (bound_names ~~ bound_Ts)
+             |> formula_from_iformula ctxt [] format mono type_enc
+                                      always_guard_var_in_formula (SOME true)
+             |> close_formula_universally
+             |> bound_tvars type_enc (n > 1) (atomic_types_of T)
+             |> maybe_negate,
+             isabelle_info format introN, NONE)
+  end
+
+fun formula_lines_for_tags_sym_decl ctxt format conj_sym_kind mono type_enc n s
+        (j, (s', T_args, T, pred_sym, ary, in_conj)) =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val level = level_of_type_enc type_enc
+    val grain = granularity_of_type_level level
+    val ident_base =
+      tags_sym_formula_prefix ^ s ^
+      (if n > 1 then "_" ^ string_of_int j else "")
+    val (kind, maybe_negate) =
+      if in_conj then (conj_sym_kind, conj_sym_kind = Conjecture ? mk_anot)
+      else (Axiom, I)
+    val (arg_Ts, res_T) = chop_fun ary T
+    val bound_names = 1 upto ary |> map (`I o make_bound_var o string_of_int)
+    val bounds = bound_names |> map (fn name => ATerm (name, []))
+    val cst = mk_aterm format type_enc (s, s') T_args
+    val eq = maybe_negate oo eq_formula type_enc (atomic_types_of T) pred_sym
+    val should_encode = should_encode_type ctxt mono level
+    val tag_with = tag_with_type ctxt format mono type_enc NONE
+    val add_formula_for_res =
+      if should_encode res_T then
+        let
+          val tagged_bounds =
+            if grain = Ghost_Type_Arg_Vars then
+              let val ghosts = ghost_type_args thy s ary in
+                map2 (fn (j, arg_T) => member (op =) ghosts j ? tag_with arg_T)
+                     (0 upto ary - 1 ~~ arg_Ts) bounds
+              end
+            else
+              bounds
+        in
+          cons (Formula (ident_base ^ "_res", kind,
+                         eq (tag_with res_T (cst bounds)) (cst tagged_bounds),
+                         isabelle_info format simpN, NONE))
+        end
+      else
+        I
+    fun add_formula_for_arg k =
+      let val arg_T = nth arg_Ts k in
+        if should_encode arg_T then
+          case chop k bounds of
+            (bounds1, bound :: bounds2) =>
+            cons (Formula (ident_base ^ "_arg" ^ string_of_int (k + 1), kind,
+                           eq (cst (bounds1 @ tag_with arg_T bound :: bounds2))
+                              (cst bounds),
+                           isabelle_info format simpN, NONE))
+          | _ => raise Fail "expected nonempty tail"
+        else
+          I
+      end
+  in
+    [] |> not pred_sym ? add_formula_for_res
+       |> (Config.get ctxt type_tag_arguments andalso
+           grain = Positively_Naked_Vars)
+          ? fold add_formula_for_arg (ary - 1 downto 0)
+  end
+
+fun result_type_of_decl (_, _, T, _, ary, _) = chop_fun ary T |> snd
+
+fun rationalize_decls ctxt (decls as decl :: (decls' as _ :: _)) =
+    let
+      val T = result_type_of_decl decl
+              |> map_type_tvar (fn (z, _) => TVar (z, HOLogic.typeS))
+    in
+      if forall (type_generalization ctxt T o result_type_of_decl) decls' then
+        [decl]
+      else
+        decls
+    end
+  | rationalize_decls _ decls = decls
+
+fun problem_lines_for_sym_decls ctxt format conj_sym_kind mono type_enc
+                                (s, decls) =
+  case type_enc of
+    Simple_Types _ => [decl_line_for_sym ctxt format mono type_enc s (hd decls)]
+  | Guards (_, level) =>
+    let
+      val decls = decls |> rationalize_decls ctxt
+      val n = length decls
+      val decls =
+        decls |> filter (should_encode_type ctxt mono level
+                         o result_type_of_decl)
+    in
+      (0 upto length decls - 1, decls)
+      |-> map2 (formula_line_for_guards_sym_decl ctxt format conj_sym_kind mono
+                                                 type_enc n s)
+    end
+  | Tags (_, level) =>
+    if granularity_of_type_level level = All_Vars then
+      []
+    else
+      let val n = length decls in
+        (0 upto n - 1 ~~ decls)
+        |> maps (formula_lines_for_tags_sym_decl ctxt format conj_sym_kind mono
+                                                 type_enc n s)
+      end
+
+fun problem_lines_for_sym_decl_table ctxt format conj_sym_kind mono type_enc
+                                     mono_Ts sym_decl_tab =
+  let
+    val syms = sym_decl_tab |> Symtab.dest |> sort_wrt fst
+    val mono_lines =
+      problem_lines_for_mono_types ctxt format mono type_enc mono_Ts
+    val decl_lines =
+      fold_rev (append o problem_lines_for_sym_decls ctxt format conj_sym_kind
+                             mono type_enc)
+               syms []
+  in mono_lines @ decl_lines end
+
+fun needs_type_tag_idempotence ctxt (Tags (poly, level)) =
+    Config.get ctxt type_tag_idempotence andalso
+    is_type_level_monotonicity_based level andalso
+    poly <> Mangled_Monomorphic
+  | needs_type_tag_idempotence _ _ = false
+
+val implicit_declsN = "Should-be-implicit typings"
+val explicit_declsN = "Explicit typings"
+val factsN = "Relevant facts"
+val class_relsN = "Class relationships"
+val aritiesN = "Arities"
+val helpersN = "Helper facts"
+val conjsN = "Conjectures"
+val free_typesN = "Type variables"
+
+(* TFF allows implicit declarations of types, function symbols, and predicate
+   symbols (with "$i" as the type of individuals), but some provers (e.g.,
+   SNARK) require explicit declarations. The situation is similar for THF. *)
+
+fun default_type type_enc pred_sym s =
+  let
+    val ind =
+      case type_enc of
+        Simple_Types _ =>
+        if String.isPrefix type_const_prefix s then atype_of_types
+        else individual_atype
+      | _ => individual_atype
+    fun typ 0 = if pred_sym then bool_atype else ind
+      | typ ary = AFun (ind, typ (ary - 1))
+  in typ end
+
+fun nary_type_constr_type n =
+  funpow n (curry AFun atype_of_types) atype_of_types
+
+fun undeclared_syms_in_problem type_enc problem =
+  let
+    val declared = declared_syms_in_problem problem
+    fun do_sym name ty =
+      if member (op =) declared name then I else AList.default (op =) (name, ty)
+    fun do_type (AType (name as (s, _), tys)) =
+        is_tptp_user_symbol s
+        ? do_sym name (fn () => nary_type_constr_type (length tys))
+        #> fold do_type tys
+      | do_type (AFun (ty1, ty2)) = do_type ty1 #> do_type ty2
+      | do_type (ATyAbs (_, ty)) = do_type ty
+    fun do_term pred_sym (ATerm (name as (s, _), tms)) =
+        is_tptp_user_symbol s
+        ? do_sym name (fn _ => default_type type_enc pred_sym s (length tms))
+        #> fold (do_term false) tms
+      | do_term _ (AAbs ((_, ty), tm)) = do_type ty #> do_term false tm
+    fun do_formula (AQuant (_, xs, phi)) =
+        fold do_type (map_filter snd xs) #> do_formula phi
+      | do_formula (AConn (_, phis)) = fold do_formula phis
+      | do_formula (AAtom tm) = do_term true tm
+    fun do_problem_line (Decl (_, _, ty)) = do_type ty
+      | do_problem_line (Formula (_, _, phi, _, _)) = do_formula phi
+  in
+    fold (fold do_problem_line o snd) problem []
+    |> filter_out (is_built_in_tptp_symbol o fst o fst)
+  end
+
+fun declare_undeclared_syms_in_atp_problem type_enc problem =
+  let
+    val decls =
+      problem
+      |> undeclared_syms_in_problem type_enc
+      |> sort_wrt (fst o fst)
+      |> map (fn (x as (s, _), ty) => Decl (type_decl_prefix ^ s, x, ty ()))
+  in (implicit_declsN, decls) :: problem end
+
+fun exists_subdtype P =
+  let
+    fun ex U = P U orelse
+      (case U of Datatype.DtType (_, Us) => exists ex Us | _ => false)
+  in ex end
+
+fun is_poly_constr (_, Us) =
+  exists (exists_subdtype (fn Datatype.DtTFree _ => true | _ => false)) Us
+
+fun all_constrs_of_polymorphic_datatypes thy =
+  Symtab.fold (snd
+               #> #descr
+               #> maps (snd #> #3)
+               #> (fn cs => exists is_poly_constr cs ? append cs))
+              (Datatype.get_all thy) []
+  |> List.partition is_poly_constr
+  |> pairself (map fst)
+
+(* Forcing explicit applications is expensive for polymorphic encodings, because
+   it takes only one existential variable ranging over "'a => 'b" to ruin
+   everything. Hence we do it only if there are few facts (is normally the case
+   for "metis" and the minimizer. *)
+val explicit_apply_threshold = 50
+
+fun prepare_atp_problem ctxt format conj_sym_kind prem_kind type_enc exporter
+                        lam_trans readable_names preproc hyp_ts concl_t facts =
+  let
+    val thy = Proof_Context.theory_of ctxt
+    val type_enc = type_enc |> adjust_type_enc format
+    val explicit_apply =
+      if polymorphism_of_type_enc type_enc <> Polymorphic orelse
+         length facts <= explicit_apply_threshold then
+        NONE
+      else
+        SOME false
+    val lam_trans =
+      if lam_trans = keep_lamsN andalso
+         not (is_type_enc_higher_order type_enc) then
+        error ("Lambda translation scheme incompatible with first-order \
+               \encoding.")
+      else
+        lam_trans
+    val (fact_names, classes, conjs, facts, class_rel_clauses, arity_clauses,
+         lifted) =
+      translate_formulas ctxt format prem_kind type_enc lam_trans preproc hyp_ts
+                         concl_t facts
+    val sym_tab = sym_table_for_facts ctxt type_enc explicit_apply conjs facts
+    val mono = conjs @ facts |> mononotonicity_info_for_facts ctxt type_enc
+    val (polym_constrs, monom_constrs) =
+      all_constrs_of_polymorphic_datatypes thy
+      |>> map (make_fixed_const (SOME format))
+    val firstorderize =
+      firstorderize_fact thy monom_constrs format type_enc sym_tab
+    val (conjs, facts) = (conjs, facts) |> pairself (map firstorderize)
+    val sym_tab = sym_table_for_facts ctxt type_enc (SOME false) conjs facts
+    val helpers =
+      sym_tab |> helper_facts_for_sym_table ctxt format type_enc
+              |> map firstorderize
+    val mono_Ts =
+      helpers @ conjs @ facts |> monotonic_types_for_facts ctxt mono type_enc
+    val class_decl_lines = decl_lines_for_classes type_enc classes
+    val sym_decl_lines =
+      (conjs, helpers @ facts)
+      |> sym_decl_table_for_facts ctxt format type_enc sym_tab
+      |> problem_lines_for_sym_decl_table ctxt format conj_sym_kind mono
+                                               type_enc mono_Ts
+    val helper_lines =
+      0 upto length helpers - 1 ~~ helpers
+      |> map (formula_line_for_fact ctxt polym_constrs format helper_prefix I
+                                    false true mono type_enc)
+      |> (if needs_type_tag_idempotence ctxt type_enc then
+            cons (type_tag_idempotence_fact format type_enc)
+          else
+            I)
+    (* Reordering these might confuse the proof reconstruction code or the SPASS
+       FLOTTER hack. *)
+    val problem =
+      [(explicit_declsN, class_decl_lines @ sym_decl_lines),
+       (factsN,
+        map (formula_line_for_fact ctxt polym_constrs format fact_prefix
+                 ascii_of (not exporter) (not exporter) mono type_enc)
+            (0 upto length facts - 1 ~~ facts)),
+       (class_relsN,
+        map (formula_line_for_class_rel_clause format type_enc)
+            class_rel_clauses),
+       (aritiesN,
+        map (formula_line_for_arity_clause format type_enc) arity_clauses),
+       (helpersN, helper_lines),
+       (conjsN,
+        map (formula_line_for_conjecture ctxt polym_constrs format mono
+                                         type_enc) conjs),
+       (free_typesN, formula_lines_for_free_types type_enc (facts @ conjs))]
+    val problem =
+      problem
+      |> (case format of
+            CNF => ensure_cnf_problem
+          | CNF_UEQ => filter_cnf_ueq_problem
+          | FOF => I
+          | TFF (_, TPTP_Implicit) => I
+          | THF (_, TPTP_Implicit, _) => I
+          | _ => declare_undeclared_syms_in_atp_problem type_enc)
+    val (problem, pool) = problem |> nice_atp_problem readable_names format
+    fun add_sym_ary (s, {min_ary, ...} : sym_info) =
+      min_ary > 0 ? Symtab.insert (op =) (s, min_ary)
+  in
+    (problem,
+     case pool of SOME the_pool => snd the_pool | NONE => Symtab.empty,
+     fact_names |> Vector.fromList,
+     lifted,
+     Symtab.empty |> Symtab.fold add_sym_ary sym_tab)
+  end
+
+(* FUDGE *)
+val conj_weight = 0.0
+val hyp_weight = 0.1
+val fact_min_weight = 0.2
+val fact_max_weight = 1.0
+val type_info_default_weight = 0.8
+
+fun add_term_weights weight (ATerm (s, tms)) =
+    is_tptp_user_symbol s ? Symtab.default (s, weight)
+    #> fold (add_term_weights weight) tms
+  | add_term_weights weight (AAbs (_, tm)) = add_term_weights weight tm
+fun add_problem_line_weights weight (Formula (_, _, phi, _, _)) =
+    formula_fold NONE (K (add_term_weights weight)) phi
+  | add_problem_line_weights _ _ = I
+
+fun add_conjectures_weights [] = I
+  | add_conjectures_weights conjs =
+    let val (hyps, conj) = split_last conjs in
+      add_problem_line_weights conj_weight conj
+      #> fold (add_problem_line_weights hyp_weight) hyps
+    end
+
+fun add_facts_weights facts =
+  let
+    val num_facts = length facts
+    fun weight_of j =
+      fact_min_weight + (fact_max_weight - fact_min_weight) * Real.fromInt j
+                        / Real.fromInt num_facts
+  in
+    map weight_of (0 upto num_facts - 1) ~~ facts
+    |> fold (uncurry add_problem_line_weights)
+  end
+
+(* Weights are from 0.0 (most important) to 1.0 (least important). *)
+fun atp_problem_weights problem =
+  let val get = these o AList.lookup (op =) problem in
+    Symtab.empty
+    |> add_conjectures_weights (get free_typesN @ get conjsN)
+    |> add_facts_weights (get factsN)
+    |> fold (fold (add_problem_line_weights type_info_default_weight) o get)
+            [explicit_declsN, class_relsN, aritiesN]
+    |> Symtab.dest
+    |> sort (prod_ord Real.compare string_ord o pairself swap)
+  end
+
+end;