src/HOL/Tools/inductive_package.ML
author berghofe
Wed Jul 15 18:26:15 1998 +0200 (1998-07-15)
changeset 5149 10f0be29c0d1
parent 5120 f7f5442c934a
child 5179 819f90f278db
permissions -rw-r--r--
Fixed bug in transform_rule.
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(*  Title:      HOL/Tools/inductive_package.ML
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    ID:         $Id$
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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                Stefan Berghofer,   TU Muenchen
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    Copyright   1994  University of Cambridge
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                1998  TU Muenchen     
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(Co)Inductive Definition module for HOL
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Features:
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* least or greatest fixedpoints
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* user-specified product and sum constructions
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* mutually recursive definitions
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* definitions involving arbitrary monotone operators
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* automatically proves introduction and elimination rules
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The recursive sets must *already* be declared as constants in parent theory!
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  Introduction rules have the form
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  [| ti:M(Sj), ..., P(x), ... |] ==> t: Sk |]
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  where M is some monotone operator (usually the identity)
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  P(x) is any side condition on the free variables
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  ti, t are any terms
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  Sj, Sk are two of the sets being defined in mutual recursion
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Sums are used only for mutual recursion;
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Products are used only to derive "streamlined" induction rules for relations
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*)
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signature INDUCTIVE_PACKAGE =
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sig
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  val add_inductive_i : bool -> bool -> bstring -> bool -> bool -> bool -> term list ->
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    term list -> thm list -> thm list -> theory -> theory *
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      {defs:thm list, elims:thm list, raw_induct:thm, induct:thm,
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       intrs:thm list,
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       mk_cases:thm list -> string -> thm, mono:thm,
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       unfold:thm}
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  val add_inductive : bool -> bool -> string list -> string list
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    -> thm list -> thm list -> theory -> theory *
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      {defs:thm list, elims:thm list, raw_induct:thm, induct:thm,
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       intrs:thm list,
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       mk_cases:thm list -> string -> thm, mono:thm,
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       unfold:thm}
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end;
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structure InductivePackage : INDUCTIVE_PACKAGE =
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struct
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(*For proving monotonicity of recursion operator*)
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val basic_monos = [subset_refl, imp_refl, disj_mono, conj_mono, 
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                   ex_mono, Collect_mono, in_mono, vimage_mono];
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val Const _ $ (vimage_f $ _) $ _ = HOLogic.dest_Trueprop (concl_of vimageD);
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(*Delete needless equality assumptions*)
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val refl_thin = prove_goal HOL.thy "!!P. [| a=a;  P |] ==> P"
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     (fn _ => [assume_tac 1]);
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(*For simplifying the elimination rule*)
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val elim_rls = [asm_rl, FalseE, refl_thin, conjE, exE, Pair_inject];
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val vimage_name = Sign.intern_const (sign_of Vimage.thy) "op -``";
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val mono_name = Sign.intern_const (sign_of Ord.thy) "mono";
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(* make injections needed in mutually recursive definitions *)
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fun mk_inj cs sumT c x =
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  let
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    fun mk_inj' T n i =
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      if n = 1 then x else
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      let val n2 = n div 2;
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          val Type (_, [T1, T2]) = T
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      in
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        if i <= n2 then
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          Const ("Inl", T1 --> T) $ (mk_inj' T1 n2 i)
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        else
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          Const ("Inr", T2 --> T) $ (mk_inj' T2 (n - n2) (i - n2))
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      end
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  in mk_inj' sumT (length cs) (1 + find_index_eq c cs)
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  end;
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(* make "vimage" terms for selecting out components of mutually rec.def. *)
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fun mk_vimage cs sumT t c = if length cs < 2 then t else
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  let
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    val cT = HOLogic.dest_setT (fastype_of c);
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    val vimageT = [cT --> sumT, HOLogic.mk_setT sumT] ---> HOLogic.mk_setT cT
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  in
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    Const (vimage_name, vimageT) $
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      Abs ("y", cT, mk_inj cs sumT c (Bound 0)) $ t
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  end;
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(**************************** well-formedness checks **************************)
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fun err_in_rule sign t msg = error ("Ill-formed introduction rule\n" ^
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  (Sign.string_of_term sign t) ^ "\n" ^ msg);
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fun err_in_prem sign t p msg = error ("Ill-formed premise\n" ^
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  (Sign.string_of_term sign p) ^ "\nin introduction rule\n" ^
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  (Sign.string_of_term sign t) ^ "\n" ^ msg);
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val msg1 = "Conclusion of introduction rule must have form\
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          \ ' t : S_i '";
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val msg2 = "Premises mentioning recursive sets must have form\
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          \ ' t : M S_i '";
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val msg3 = "Recursion term on left of member symbol";
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fun check_rule sign cs r =
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  let
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    fun check_prem prem = if exists (Logic.occs o (rpair prem)) cs then
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         (case prem of
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           (Const ("op :", _) $ t $ u) =>
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             if exists (Logic.occs o (rpair t)) cs then
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               err_in_prem sign r prem msg3 else ()
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         | _ => err_in_prem sign r prem msg2)
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        else ()
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  in (case (HOLogic.dest_Trueprop o Logic.strip_imp_concl) r of
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        (Const ("op :", _) $ _ $ u) =>
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          if u mem cs then map (check_prem o HOLogic.dest_Trueprop)
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            (Logic.strip_imp_prems r)
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          else err_in_rule sign r msg1
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      | _ => err_in_rule sign r msg1)
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  end;
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fun try' f msg sign t = (f t) handle _ => error (msg ^ Sign.string_of_term sign t);
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(*********************** properties of (co)inductive sets *********************)
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(***************************** elimination rules ******************************)
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fun mk_elims cs cTs params intr_ts =
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  let
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    val used = foldr add_term_names (intr_ts, []);
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    val [aname, pname] = variantlist (["a", "P"], used);
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    val P = HOLogic.mk_Trueprop (Free (pname, HOLogic.boolT));
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    fun dest_intr r =
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      let val Const ("op :", _) $ t $ u =
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        HOLogic.dest_Trueprop (Logic.strip_imp_concl r)
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      in (u, t, Logic.strip_imp_prems r) end;
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    val intrs = map dest_intr intr_ts;
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    fun mk_elim (c, T) =
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      let
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        val a = Free (aname, T);
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        fun mk_elim_prem (_, t, ts) =
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          list_all_free (map dest_Free ((foldr add_term_frees (t::ts, [])) \\ params),
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            Logic.list_implies (HOLogic.mk_Trueprop (HOLogic.mk_eq (a, t)) :: ts, P));
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      in
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        Logic.list_implies (HOLogic.mk_Trueprop (HOLogic.mk_mem (a, c)) ::
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          map mk_elim_prem (filter (equal c o #1) intrs), P)
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      end
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  in
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    map mk_elim (cs ~~ cTs)
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  end;
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(***************** premises and conclusions of induction rules ****************)
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fun mk_indrule cs cTs params intr_ts =
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  let
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    val used = foldr add_term_names (intr_ts, []);
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    (* predicates for induction rule *)
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    val preds = map Free (variantlist (if length cs < 2 then ["P"] else
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      map (fn i => "P" ^ string_of_int i) (1 upto length cs), used) ~~
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        map (fn T => T --> HOLogic.boolT) cTs);
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    (* transform an introduction rule into a premise for induction rule *)
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    fun mk_ind_prem r =
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      let
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        val frees = map dest_Free ((add_term_frees (r, [])) \\ params);
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        fun subst (prem as (Const ("op :", T) $ t $ u), prems) =
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              let val n = find_index_eq u cs in
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                if n >= 0 then prem :: (nth_elem (n, preds)) $ t :: prems else
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                  (subst_free (map (fn (c, P) => (c, HOLogic.mk_binop "op Int"
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                    (c, HOLogic.Collect_const (HOLogic.dest_setT
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                      (fastype_of c)) $ P))) (cs ~~ preds)) prem)::prems
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              end
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          | subst (prem, prems) = prem::prems;
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        val Const ("op :", _) $ t $ u =
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          HOLogic.dest_Trueprop (Logic.strip_imp_concl r)
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      in list_all_free (frees,
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           Logic.list_implies (map HOLogic.mk_Trueprop (foldr subst
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             (map HOLogic.dest_Trueprop (Logic.strip_imp_prems r), [])),
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               HOLogic.mk_Trueprop (nth_elem (find_index_eq u cs, preds) $ t)))
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      end;
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    val ind_prems = map mk_ind_prem intr_ts;
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    (* make conclusions for induction rules *)
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    fun mk_ind_concl ((c, P), (ts, x)) =
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      let val T = HOLogic.dest_setT (fastype_of c);
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          val Ts = HOLogic.prodT_factors T;
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          val (frees, x') = foldr (fn (T', (fs, s)) =>
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            ((Free (s, T'))::fs, bump_string s)) (Ts, ([], x));
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          val tuple = HOLogic.mk_tuple T frees;
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      in ((HOLogic.mk_binop "op -->"
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        (HOLogic.mk_mem (tuple, c), P $ tuple))::ts, x')
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      end;
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    val mutual_ind_concl = HOLogic.mk_Trueprop (foldr1 (app HOLogic.conj)
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        (fst (foldr mk_ind_concl (cs ~~ preds, ([], "xa")))))
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  in (preds, ind_prems, mutual_ind_concl)
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  end;
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(********************** proofs for (co)inductive sets *************************)
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(**************************** prove monotonicity ******************************)
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fun prove_mono setT fp_fun monos thy =
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  let
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    val _ = writeln "  Proving monotonicity...";
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    val mono = prove_goalw_cterm [] (cterm_of (sign_of thy) (HOLogic.mk_Trueprop
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      (Const (mono_name, (setT --> setT) --> HOLogic.boolT) $ fp_fun)))
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        (fn _ => [rtac monoI 1, REPEAT (ares_tac (basic_monos @ monos) 1)])
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  in mono end;
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(************************* prove introduction rules ***************************)
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fun prove_intrs coind mono fp_def intr_ts con_defs rec_sets_defs thy =
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  let
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    val _ = writeln "  Proving the introduction rules...";
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    val unfold = standard (mono RS (fp_def RS
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      (if coind then def_gfp_Tarski else def_lfp_Tarski)));
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    fun select_disj 1 1 = []
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      | select_disj _ 1 = [rtac disjI1]
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      | select_disj n i = (rtac disjI2)::(select_disj (n - 1) (i - 1));
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    val intrs = map (fn (i, intr) => prove_goalw_cterm rec_sets_defs
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      (cterm_of (sign_of thy) intr) (fn prems =>
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       [(*insert prems and underlying sets*)
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       cut_facts_tac prems 1,
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       stac unfold 1,
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       REPEAT (resolve_tac [vimageI2, CollectI] 1),
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       (*Now 1-2 subgoals: the disjunction, perhaps equality.*)
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       EVERY1 (select_disj (length intr_ts) i),
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       (*Not ares_tac, since refl must be tried before any equality assumptions;
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         backtracking may occur if the premises have extra variables!*)
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       DEPTH_SOLVE_1 (resolve_tac [refl,exI,conjI] 1 APPEND assume_tac 1),
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       (*Now solve the equations like Inl 0 = Inl ?b2*)
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       rewrite_goals_tac con_defs,
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       REPEAT (rtac refl 1)])) (1 upto (length intr_ts) ~~ intr_ts)
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  in (intrs, unfold) end;
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(*************************** prove elimination rules **************************)
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fun prove_elims cs cTs params intr_ts unfold rec_sets_defs thy =
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  let
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    val _ = writeln "  Proving the elimination rules...";
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    val rules1 = [CollectE, disjE, make_elim vimageD];
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    val rules2 = [exE, conjE, Inl_neq_Inr, Inr_neq_Inl] @
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      map make_elim [Inl_inject, Inr_inject];
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    val elims = map (fn t => prove_goalw_cterm rec_sets_defs
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      (cterm_of (sign_of thy) t) (fn prems =>
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        [cut_facts_tac [hd prems] 1,
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         dtac (unfold RS subst) 1,
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         REPEAT (FIRSTGOAL (eresolve_tac rules1)),
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         REPEAT (FIRSTGOAL (eresolve_tac rules2)),
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         EVERY (map (fn prem =>
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           DEPTH_SOLVE_1 (ares_tac [prem, conjI] 1)) (tl prems))]))
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      (mk_elims cs cTs params intr_ts)
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  in elims end;
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(** derivation of simplified elimination rules **)
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(*Applies freeness of the given constructors, which *must* be unfolded by
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  the given defs.  Cannot simply use the local con_defs because con_defs=[] 
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  for inference systems.
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 *)
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fun con_elim_tac simps =
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  let val elim_tac = REPEAT o (eresolve_tac elim_rls)
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  in ALLGOALS(EVERY'[elim_tac,
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                 asm_full_simp_tac (simpset_of Nat.thy addsimps simps),
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                 elim_tac,
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                 REPEAT o bound_hyp_subst_tac])
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     THEN prune_params_tac
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  end;
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(*String s should have the form t:Si where Si is an inductive set*)
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fun mk_cases elims simps s =
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  let val prem = assume (read_cterm (sign_of_thm (hd elims)) (s, propT));
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      val elims' = map (try (fn r =>
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        rule_by_tactic (con_elim_tac simps) (prem RS r) |> standard)) elims
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  in case find_first is_some elims' of
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       Some (Some r) => r
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     | None => error ("mk_cases: string '" ^ s ^ "' not of form 't : S_i'")
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  end;
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(**************************** prove induction rule ****************************)
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fun prove_indrule cs cTs sumT rec_const params intr_ts mono
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    fp_def rec_sets_defs thy =
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  let
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    val _ = writeln "  Proving the induction rule...";
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    val sign = sign_of thy;
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    val (preds, ind_prems, mutual_ind_concl) = mk_indrule cs cTs params intr_ts;
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    (* make predicate for instantiation of abstract induction rule *)
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    fun mk_ind_pred _ [P] = P
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      | mk_ind_pred T Ps =
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   322
         let val n = (length Ps) div 2;
berghofe@5094
   323
             val Type (_, [T1, T2]) = T
berghofe@5094
   324
         in Const ("sum_case",
berghofe@5094
   325
           [T1 --> HOLogic.boolT, T2 --> HOLogic.boolT, T] ---> HOLogic.boolT) $
berghofe@5094
   326
             mk_ind_pred T1 (take (n, Ps)) $ mk_ind_pred T2 (drop (n, Ps))
berghofe@5094
   327
         end;
berghofe@5094
   328
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   329
    val ind_pred = mk_ind_pred sumT preds;
berghofe@5094
   330
berghofe@5094
   331
    val ind_concl = HOLogic.mk_Trueprop
berghofe@5094
   332
      (HOLogic.all_const sumT $ Abs ("x", sumT, HOLogic.mk_binop "op -->"
berghofe@5094
   333
        (HOLogic.mk_mem (Bound 0, rec_const), ind_pred $ Bound 0)));
berghofe@5094
   334
berghofe@5094
   335
    (* simplification rules for vimage and Collect *)
berghofe@5094
   336
berghofe@5094
   337
    val vimage_simps = if length cs < 2 then [] else
berghofe@5094
   338
      map (fn c => prove_goalw_cterm [] (cterm_of sign
berghofe@5094
   339
        (HOLogic.mk_Trueprop (HOLogic.mk_eq
berghofe@5094
   340
          (mk_vimage cs sumT (HOLogic.Collect_const sumT $ ind_pred) c,
berghofe@5094
   341
           HOLogic.Collect_const (HOLogic.dest_setT (fastype_of c)) $
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   342
             nth_elem (find_index_eq c cs, preds)))))
berghofe@5094
   343
        (fn _ => [rtac vimage_Collect 1, rewrite_goals_tac
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   344
           (map mk_meta_eq [sum_case_Inl, sum_case_Inr]),
berghofe@5094
   345
          rtac refl 1])) cs;
berghofe@5094
   346
berghofe@5094
   347
    val induct = prove_goalw_cterm [] (cterm_of sign
berghofe@5094
   348
      (Logic.list_implies (ind_prems, ind_concl))) (fn prems =>
berghofe@5094
   349
        [rtac (impI RS allI) 1,
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   350
         DETERM (etac (mono RS (fp_def RS def_induct)) 1),
berghofe@5094
   351
         rewrite_goals_tac (map mk_meta_eq (vimage_Int::vimage_simps)),
berghofe@5094
   352
         fold_goals_tac rec_sets_defs,
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   353
         (*This CollectE and disjE separates out the introduction rules*)
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   354
         REPEAT (FIRSTGOAL (eresolve_tac [CollectE, disjE])),
berghofe@5094
   355
         (*Now break down the individual cases.  No disjE here in case
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   356
           some premise involves disjunction.*)
berghofe@5094
   357
         REPEAT (FIRSTGOAL (eresolve_tac [IntE, CollectE, exE, conjE] 
berghofe@5094
   358
                     ORELSE' hyp_subst_tac)),
berghofe@5094
   359
         rewrite_goals_tac (map mk_meta_eq [sum_case_Inl, sum_case_Inr]),
berghofe@5094
   360
         EVERY (map (fn prem =>
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   361
           DEPTH_SOLVE_1 (ares_tac [prem, conjI, refl] 1)) prems)]);
berghofe@5094
   362
berghofe@5094
   363
    val lemma = prove_goalw_cterm rec_sets_defs (cterm_of sign
berghofe@5094
   364
      (Logic.mk_implies (ind_concl, mutual_ind_concl))) (fn prems =>
berghofe@5094
   365
        [cut_facts_tac prems 1,
berghofe@5094
   366
         REPEAT (EVERY
berghofe@5094
   367
           [REPEAT (resolve_tac [conjI, impI] 1),
berghofe@5094
   368
            TRY (dtac vimageD 1), etac allE 1, dtac mp 1, atac 1,
berghofe@5094
   369
            rewrite_goals_tac (map mk_meta_eq [sum_case_Inl, sum_case_Inr]),
berghofe@5094
   370
            atac 1])])
berghofe@5094
   371
berghofe@5094
   372
  in standard (split_rule (induct RS lemma))
berghofe@5094
   373
  end;
berghofe@5094
   374
berghofe@5094
   375
(*************** definitional introduction of (co)inductive sets **************)
berghofe@5094
   376
berghofe@5094
   377
fun add_ind_def verbose declare_consts alt_name coind no_elim no_ind cs
berghofe@5094
   378
    intr_ts monos con_defs thy params paramTs cTs cnames =
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   379
  let
berghofe@5094
   380
    val _ = if verbose then writeln ("Proofs for " ^
berghofe@5094
   381
      (if coind then "co" else "") ^ "inductive set(s) " ^ commas cnames) else ();
berghofe@5094
   382
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   383
    val sumT = fold_bal (fn (T, U) => Type ("+", [T, U])) cTs;
berghofe@5094
   384
    val setT = HOLogic.mk_setT sumT;
berghofe@5094
   385
berghofe@5094
   386
    val fp_name = if coind then Sign.intern_const (sign_of Gfp.thy) "gfp"
berghofe@5094
   387
      else Sign.intern_const (sign_of Lfp.thy) "lfp";
berghofe@5094
   388
berghofe@5149
   389
    val used = foldr add_term_names (intr_ts, []);
berghofe@5149
   390
    val [sname, xname] = variantlist (["S", "x"], used);
berghofe@5149
   391
berghofe@5094
   392
    (* transform an introduction rule into a conjunction  *)
berghofe@5094
   393
    (*   [| t : ... S_i ... ; ... |] ==> u : S_j          *)
berghofe@5094
   394
    (* is transformed into                                *)
berghofe@5094
   395
    (*   x = Inj_j u & t : ... Inj_i -`` S ... & ...      *)
berghofe@5094
   396
berghofe@5094
   397
    fun transform_rule r =
berghofe@5094
   398
      let
berghofe@5094
   399
        val frees = map dest_Free ((add_term_frees (r, [])) \\ params);
berghofe@5149
   400
        val subst = subst_free
berghofe@5149
   401
          (cs ~~ (map (mk_vimage cs sumT (Free (sname, setT))) cs));
berghofe@5094
   402
        val Const ("op :", _) $ t $ u =
berghofe@5094
   403
          HOLogic.dest_Trueprop (Logic.strip_imp_concl r)
berghofe@5094
   404
berghofe@5094
   405
      in foldr (fn ((x, T), P) => HOLogic.mk_exists (x, T, P))
berghofe@5094
   406
        (frees, foldr1 (app HOLogic.conj)
berghofe@5149
   407
          (((HOLogic.eq_const sumT) $ Free (xname, sumT) $ (mk_inj cs sumT u t))::
berghofe@5094
   408
            (map (subst o HOLogic.dest_Trueprop)
berghofe@5094
   409
              (Logic.strip_imp_prems r))))
berghofe@5094
   410
      end
berghofe@5094
   411
berghofe@5094
   412
    (* make a disjunction of all introduction rules *)
berghofe@5094
   413
berghofe@5149
   414
    val fp_fun = absfree (sname, setT, (HOLogic.Collect_const sumT) $
berghofe@5149
   415
      absfree (xname, sumT, foldr1 (app HOLogic.disj) (map transform_rule intr_ts)));
berghofe@5094
   416
berghofe@5094
   417
    (* add definiton of recursive sets to theory *)
berghofe@5094
   418
berghofe@5094
   419
    val rec_name = if alt_name = "" then space_implode "_" cnames else alt_name;
berghofe@5094
   420
    val full_rec_name = Sign.full_name (sign_of thy) rec_name;
berghofe@5094
   421
berghofe@5094
   422
    val rec_const = list_comb
berghofe@5094
   423
      (Const (full_rec_name, paramTs ---> setT), params);
berghofe@5094
   424
berghofe@5094
   425
    val fp_def_term = Logic.mk_equals (rec_const,
berghofe@5094
   426
      Const (fp_name, (setT --> setT) --> setT) $ fp_fun)
berghofe@5094
   427
berghofe@5094
   428
    val def_terms = fp_def_term :: (if length cs < 2 then [] else
berghofe@5094
   429
      map (fn c => Logic.mk_equals (c, mk_vimage cs sumT rec_const c)) cs);
berghofe@5094
   430
berghofe@5094
   431
    val thy' = thy |>
berghofe@5094
   432
      (if declare_consts then
berghofe@5094
   433
        Theory.add_consts_i (map (fn (c, n) =>
berghofe@5094
   434
          (n, paramTs ---> fastype_of c, NoSyn)) (cs ~~ cnames))
berghofe@5094
   435
       else I) |>
berghofe@5094
   436
      (if length cs < 2 then I else
berghofe@5094
   437
       Theory.add_consts_i [(rec_name, paramTs ---> setT, NoSyn)]) |>
berghofe@5094
   438
      Theory.add_path rec_name |>
berghofe@5094
   439
      PureThy.add_defss_i [(("defs", def_terms), [])];
berghofe@5094
   440
berghofe@5094
   441
    (* get definitions from theory *)
berghofe@5094
   442
berghofe@5094
   443
    val fp_def::rec_sets_defs = get_thms thy' "defs";
berghofe@5094
   444
berghofe@5094
   445
    (* prove and store theorems *)
berghofe@5094
   446
berghofe@5094
   447
    val mono = prove_mono setT fp_fun monos thy';
berghofe@5094
   448
    val (intrs, unfold) = prove_intrs coind mono fp_def intr_ts con_defs
berghofe@5094
   449
      rec_sets_defs thy';
berghofe@5094
   450
    val elims = if no_elim then [] else
berghofe@5094
   451
      prove_elims cs cTs params intr_ts unfold rec_sets_defs thy';
berghofe@5094
   452
    val raw_induct = if no_ind then TrueI else
berghofe@5094
   453
      if coind then standard (rule_by_tactic
berghofe@5094
   454
        (rewrite_tac [mk_meta_eq vimage_Un] THEN
berghofe@5094
   455
          fold_tac rec_sets_defs) (mono RS (fp_def RS def_Collect_coinduct)))
berghofe@5094
   456
      else
berghofe@5094
   457
        prove_indrule cs cTs sumT rec_const params intr_ts mono fp_def
berghofe@5094
   458
          rec_sets_defs thy';
berghofe@5108
   459
    val induct = if coind orelse no_ind orelse length cs > 1 then raw_induct
berghofe@5094
   460
      else standard (raw_induct RSN (2, rev_mp));
berghofe@5094
   461
berghofe@5094
   462
    val thy'' = thy' |>
berghofe@5094
   463
      PureThy.add_tthmss [(("intrs", map Attribute.tthm_of intrs), [])] |>
berghofe@5094
   464
      (if no_elim then I else PureThy.add_tthmss
berghofe@5094
   465
        [(("elims", map Attribute.tthm_of elims), [])]) |>
berghofe@5094
   466
      (if no_ind then I else PureThy.add_tthms
berghofe@5094
   467
        [(((if coind then "co" else "") ^ "induct",
berghofe@5094
   468
          Attribute.tthm_of induct), [])]) |>
berghofe@5094
   469
      Theory.parent_path;
berghofe@5094
   470
berghofe@5094
   471
  in (thy'',
berghofe@5094
   472
    {defs = fp_def::rec_sets_defs,
berghofe@5094
   473
     mono = mono,
berghofe@5094
   474
     unfold = unfold,
berghofe@5094
   475
     intrs = intrs,
berghofe@5094
   476
     elims = elims,
berghofe@5094
   477
     mk_cases = mk_cases elims,
berghofe@5094
   478
     raw_induct = raw_induct,
berghofe@5094
   479
     induct = induct})
berghofe@5094
   480
  end;
berghofe@5094
   481
berghofe@5094
   482
(***************** axiomatic introduction of (co)inductive sets ***************)
berghofe@5094
   483
berghofe@5094
   484
fun add_ind_axm verbose declare_consts alt_name coind no_elim no_ind cs
berghofe@5094
   485
    intr_ts monos con_defs thy params paramTs cTs cnames =
berghofe@5094
   486
  let
berghofe@5094
   487
    val _ = if verbose then writeln ("Adding axioms for " ^
berghofe@5094
   488
      (if coind then "co" else "") ^ "inductive set(s) " ^ commas cnames) else ();
berghofe@5094
   489
berghofe@5094
   490
    val rec_name = if alt_name = "" then space_implode "_" cnames else alt_name;
berghofe@5094
   491
berghofe@5094
   492
    val elim_ts = mk_elims cs cTs params intr_ts;
berghofe@5094
   493
berghofe@5094
   494
    val (_, ind_prems, mutual_ind_concl) = mk_indrule cs cTs params intr_ts;
berghofe@5094
   495
    val ind_t = Logic.list_implies (ind_prems, mutual_ind_concl);
berghofe@5094
   496
    
berghofe@5094
   497
    val thy' = thy |>
berghofe@5094
   498
      (if declare_consts then
berghofe@5094
   499
        Theory.add_consts_i (map (fn (c, n) =>
berghofe@5094
   500
          (n, paramTs ---> fastype_of c, NoSyn)) (cs ~~ cnames))
berghofe@5094
   501
       else I) |>
berghofe@5094
   502
      Theory.add_path rec_name |>
berghofe@5094
   503
      PureThy.add_axiomss_i [(("intrs", intr_ts), []), (("elims", elim_ts), [])] |>
berghofe@5094
   504
      (if coind then I
berghofe@5094
   505
       else PureThy.add_axioms_i [(("internal_induct", ind_t), [])]);
berghofe@5094
   506
berghofe@5094
   507
    val intrs = get_thms thy' "intrs";
berghofe@5094
   508
    val elims = get_thms thy' "elims";
berghofe@5094
   509
    val raw_induct = if coind then TrueI else
berghofe@5094
   510
      standard (split_rule (get_thm thy' "internal_induct"));
berghofe@5094
   511
    val induct = if coind orelse length cs > 1 then raw_induct
berghofe@5094
   512
      else standard (raw_induct RSN (2, rev_mp));
berghofe@5094
   513
berghofe@5094
   514
    val thy'' = thy' |>
berghofe@5094
   515
      (if coind then I
berghofe@5094
   516
       else PureThy.add_tthms [(("induct", Attribute.tthm_of induct), [])]) |>
berghofe@5094
   517
      Theory.parent_path
berghofe@5094
   518
berghofe@5094
   519
  in (thy'',
berghofe@5094
   520
    {defs = [],
berghofe@5094
   521
     mono = TrueI,
berghofe@5094
   522
     unfold = TrueI,
berghofe@5094
   523
     intrs = intrs,
berghofe@5094
   524
     elims = elims,
berghofe@5094
   525
     mk_cases = mk_cases elims,
berghofe@5094
   526
     raw_induct = raw_induct,
berghofe@5094
   527
     induct = induct})
berghofe@5094
   528
  end;
berghofe@5094
   529
berghofe@5094
   530
(********************** introduction of (co)inductive sets ********************)
berghofe@5094
   531
berghofe@5094
   532
fun add_inductive_i verbose declare_consts alt_name coind no_elim no_ind cs
berghofe@5094
   533
    intr_ts monos con_defs thy =
berghofe@5094
   534
  let
berghofe@5094
   535
    val _ = Theory.requires thy "Inductive"
berghofe@5094
   536
      ((if coind then "co" else "") ^ "inductive definitions");
berghofe@5094
   537
berghofe@5094
   538
    val sign = sign_of thy;
berghofe@5094
   539
berghofe@5094
   540
    (*parameters should agree for all mutually recursive components*)
berghofe@5094
   541
    val (_, params) = strip_comb (hd cs);
berghofe@5094
   542
    val paramTs = map (try' (snd o dest_Free) "Parameter in recursive\
berghofe@5094
   543
      \ component is not a free variable: " sign) params;
berghofe@5094
   544
berghofe@5094
   545
    val cTs = map (try' (HOLogic.dest_setT o fastype_of)
berghofe@5094
   546
      "Recursive component not of type set: " sign) cs;
berghofe@5094
   547
berghofe@5094
   548
    val cnames = map (try' (Sign.base_name o fst o dest_Const o head_of)
berghofe@5094
   549
      "Recursive set not previously declared as constant: " sign) cs;
berghofe@5094
   550
berghofe@5094
   551
    val _ = assert_all Syntax.is_identifier cnames
berghofe@5094
   552
       (fn a => "Base name of recursive set not an identifier: " ^ a);
berghofe@5094
   553
berghofe@5094
   554
    val _ = map (check_rule sign cs) intr_ts;
berghofe@5094
   555
berghofe@5094
   556
  in
berghofe@5094
   557
    (if !quick_and_dirty then add_ind_axm else add_ind_def)
berghofe@5094
   558
      verbose declare_consts alt_name coind no_elim no_ind cs intr_ts monos
berghofe@5094
   559
        con_defs thy params paramTs cTs cnames
berghofe@5094
   560
  end;
berghofe@5094
   561
berghofe@5094
   562
(***************************** external interface *****************************)
berghofe@5094
   563
berghofe@5094
   564
fun add_inductive verbose coind c_strings intr_strings monos con_defs thy =
berghofe@5094
   565
  let
berghofe@5094
   566
    val sign = sign_of thy;
berghofe@5094
   567
    val cs = map (readtm (sign_of thy) HOLogic.termTVar) c_strings;
berghofe@5094
   568
    val intr_ts = map (readtm (sign_of thy) propT) intr_strings;
berghofe@5094
   569
berghofe@5094
   570
    (* the following code ensures that each recursive set *)
berghofe@5094
   571
    (* always has the same type in all introduction rules *)
berghofe@5094
   572
berghofe@5094
   573
    val {tsig, ...} = Sign.rep_sg sign;
berghofe@5094
   574
    val add_term_consts_2 =
berghofe@5094
   575
      foldl_aterms (fn (cs, Const c) => c ins cs | (cs, _) => cs);
berghofe@5094
   576
    fun varify (t, (i, ts)) =
berghofe@5094
   577
      let val t' = map_term_types (incr_tvar (i + 1)) (Type.varify (t, []))
berghofe@5094
   578
      in (maxidx_of_term t', t'::ts) end;
berghofe@5094
   579
    val (i, cs') = foldr varify (cs, (~1, []));
berghofe@5094
   580
    val (i', intr_ts') = foldr varify (intr_ts, (i, []));
berghofe@5094
   581
    val rec_consts = foldl add_term_consts_2 ([], cs');
berghofe@5094
   582
    val intr_consts = foldl add_term_consts_2 ([], intr_ts');
berghofe@5094
   583
    fun unify (env, (cname, cT)) =
berghofe@5094
   584
      let val consts = map snd (filter (fn c => fst c = cname) intr_consts)
berghofe@5094
   585
      in (foldl (fn ((env', j'), Tp) => Type.unify tsig j' env' Tp)
berghofe@5094
   586
        (env, (replicate (length consts) cT) ~~ consts)) handle _ =>
berghofe@5094
   587
          error ("Occurrences of constant '" ^ cname ^
berghofe@5094
   588
            "' have incompatible types")
berghofe@5094
   589
      end;
berghofe@5094
   590
    val (env, _) = foldl unify (([], i'), rec_consts);
berghofe@5094
   591
    fun typ_subst_TVars_2 env T = let val T' = typ_subst_TVars env T
berghofe@5094
   592
      in if T = T' then T else typ_subst_TVars_2 env T' end;
berghofe@5094
   593
    val subst = fst o Type.freeze_thaw o
berghofe@5094
   594
      (map_term_types (typ_subst_TVars_2 env));
berghofe@5094
   595
    val cs'' = map subst cs';
berghofe@5094
   596
    val intr_ts'' = map subst intr_ts';
berghofe@5094
   597
berghofe@5094
   598
  in add_inductive_i verbose false "" coind false false cs'' intr_ts''
berghofe@5094
   599
    monos con_defs thy
berghofe@5094
   600
  end;
berghofe@5094
   601
berghofe@5094
   602
end;