src/HOL/Tools/Sledgehammer/sledgehammer_fact.ML
author blanchet
Wed Jul 11 21:43:19 2012 +0200 (2012-07-11 ago)
changeset 48250 1065c307fafe
child 48251 6cdcfbddc077
permissions -rw-r--r--
further ML structure split to permit finer-grained loading/reordering (problem to solve: MaSh needs most of Sledgehammer)
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(*  Title:      HOL/Tools/Sledgehammer/sledgehammer_fact.ML
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    Author:     Jia Meng, Cambridge University Computer Laboratory and NICTA
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    Author:     Jasmin Blanchette, TU Muenchen
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Sledgehammer fact handling.
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*)
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signature SLEDGEHAMMER_FACT =
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sig
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  type status = ATP_Problem_Generate.status
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  type stature = ATP_Problem_Generate.stature
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  type relevance_override =
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    {add : (Facts.ref * Attrib.src list) list,
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     del : (Facts.ref * Attrib.src list) list,
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     only : bool}
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  val ignore_no_atp : bool Config.T
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  val instantiate_inducts : bool Config.T
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  val no_relevance_override : relevance_override
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  val fact_from_ref :
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    Proof.context -> unit Symtab.table -> thm list -> status Termtab.table
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    -> Facts.ref * Attrib.src list -> ((string * stature) * thm) list
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  val all_facts :
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    Proof.context -> bool -> 'a Symtab.table -> bool -> thm list
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    -> thm list -> status Termtab.table
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    -> (((unit -> string) * stature) * thm) list
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  val clasimpset_rule_table_of : Proof.context -> status Termtab.table
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  val maybe_instantiate_inducts :
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    Proof.context -> term list -> term -> (((unit -> string) * 'a) * thm) list
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    -> (((unit -> string) * 'a) * thm) list
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  val maybe_filter_no_atps : Proof.context -> ('a * thm) list -> ('a * thm) list
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  val nearly_all_facts :
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    Proof.context -> bool -> relevance_override -> thm list -> term list -> term
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    -> (((unit -> string) * stature) * thm) list
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end;
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structure Sledgehammer_Fact : SLEDGEHAMMER_FACT =
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struct
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open ATP_Problem_Generate
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open Metis_Tactic
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open Sledgehammer_Util
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type relevance_override =
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  {add : (Facts.ref * Attrib.src list) list,
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   del : (Facts.ref * Attrib.src list) list,
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   only : bool}
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val sledgehammer_prefix = "Sledgehammer" ^ Long_Name.separator
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(* experimental features *)
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val ignore_no_atp =
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  Attrib.setup_config_bool @{binding sledgehammer_ignore_no_atp} (K false)
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val instantiate_inducts =
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  Attrib.setup_config_bool @{binding sledgehammer_instantiate_inducts} (K false)
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val no_relevance_override = {add = [], del = [], only = false}
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fun needs_quoting reserved s =
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  Symtab.defined reserved s orelse
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  exists (not o Lexicon.is_identifier) (Long_Name.explode s)
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fun make_name reserved multi j name =
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  (name |> needs_quoting reserved name ? quote) ^
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  (if multi then "(" ^ string_of_int j ^ ")" else "")
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fun explode_interval _ (Facts.FromTo (i, j)) = i upto j
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  | explode_interval max (Facts.From i) = i upto i + max - 1
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  | explode_interval _ (Facts.Single i) = [i]
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val backquote =
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  raw_explode #> map (fn "`" => "\\`" | s => s) #> implode #> enclose "`" "`"
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(* unfolding these can yield really huge terms *)
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val risky_defs = @{thms Bit0_def Bit1_def}
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fun is_rec_eq lhs = Term.exists_subterm (curry (op =) (head_of lhs))
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fun is_rec_def (@{const Trueprop} $ t) = is_rec_def t
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  | is_rec_def (@{const ==>} $ _ $ t2) = is_rec_def t2
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  | is_rec_def (Const (@{const_name "=="}, _) $ t1 $ t2) = is_rec_eq t1 t2
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  | is_rec_def (Const (@{const_name HOL.eq}, _) $ t1 $ t2) = is_rec_eq t1 t2
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  | is_rec_def _ = false
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fun is_assum assms th = exists (fn ct => prop_of th aconv term_of ct) assms
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fun is_chained chained_ths = member Thm.eq_thm_prop chained_ths
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fun scope_of_thm global assms chained_ths th =
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  if is_chained chained_ths th then Chained
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  else if global then Global
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  else if is_assum assms th then Assum
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  else Local
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val may_be_induction =
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  exists_subterm (fn Var (_, Type (@{type_name fun}, [_, T])) =>
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                     body_type T = @{typ bool}
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                   | _ => false)
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fun status_of_thm css_table name th =
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  (* FIXME: use structured name *)
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  if (String.isSubstring ".induct" name orelse
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      String.isSubstring ".inducts" name) andalso
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     may_be_induction (prop_of th) then
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    Induction
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  else case Termtab.lookup css_table (prop_of th) of
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    SOME status => status
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  | NONE => General
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fun stature_of_thm global assms chained_ths css_table name th =
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  (scope_of_thm global assms chained_ths th, status_of_thm css_table name th)
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fun fact_from_ref ctxt reserved chained_ths css_table (xthm as (xref, args)) =
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  let
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    val ths = Attrib.eval_thms ctxt [xthm]
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    val bracket =
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      map (enclose "[" "]" o Pretty.str_of o Args.pretty_src ctxt) args
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      |> implode
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    fun nth_name j =
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      case xref of
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        Facts.Fact s => backquote s ^ bracket
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      | Facts.Named (("", _), _) => "[" ^ bracket ^ "]"
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      | Facts.Named ((name, _), NONE) =>
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        make_name reserved (length ths > 1) (j + 1) name ^ bracket
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      | Facts.Named ((name, _), SOME intervals) =>
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        make_name reserved true
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                 (nth (maps (explode_interval (length ths)) intervals) j) name ^
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        bracket
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  in
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    (ths, (0, []))
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    |-> fold (fn th => fn (j, rest) =>
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                 let val name = nth_name j in
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                   (j + 1, ((name, stature_of_thm false [] chained_ths
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                                             css_table name th), th) :: rest)
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                 end)
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    |> snd
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  end
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(* Reject theorems with names like "List.filter.filter_list_def" or
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  "Accessible_Part.acc.defs", as these are definitions arising from packages. *)
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fun is_package_def a =
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  let val names = Long_Name.explode a in
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    (length names > 2 andalso not (hd names = "local") andalso
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     String.isSuffix "_def" a) orelse String.isSuffix "_defs" a
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  end
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(* FIXME: put other record thms here, or declare as "no_atp" *)
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fun multi_base_blacklist ctxt ho_atp =
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  ["defs", "select_defs", "update_defs", "split", "splits", "split_asm",
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   "cases", "ext_cases", "eq.simps", "eq.refl", "nchotomy", "case_cong",
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   "weak_case_cong"]
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  |> not (ho_atp orelse (Config.get ctxt instantiate_inducts)) ?
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        append ["induct", "inducts"]
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  |> map (prefix ".")
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val max_lambda_nesting = 3 (*only applies if not ho_atp*)
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fun term_has_too_many_lambdas max (t1 $ t2) =
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    exists (term_has_too_many_lambdas max) [t1, t2]
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  | term_has_too_many_lambdas max (Abs (_, _, t)) =
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    max = 0 orelse term_has_too_many_lambdas (max - 1) t
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  | term_has_too_many_lambdas _ _ = false
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(* Don't count nested lambdas at the level of formulas, since they are
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   quantifiers. *)
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fun formula_has_too_many_lambdas true _ _ = false (*i.e. ho_atp*)
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  | formula_has_too_many_lambdas _ Ts (Abs (_, T, t)) =
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      formula_has_too_many_lambdas false (T :: Ts) t
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  | formula_has_too_many_lambdas _ Ts t =
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    if member (op =) [HOLogic.boolT, propT] (fastype_of1 (Ts, t)) then
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      exists (formula_has_too_many_lambdas false Ts) (#2 (strip_comb t))
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    else
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      term_has_too_many_lambdas max_lambda_nesting t
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(* The max apply depth of any "metis" call in "Metis_Examples" (on 2007-10-31)
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   was 11. *)
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val max_apply_depth = 15
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fun apply_depth (f $ t) = Int.max (apply_depth f, apply_depth t + 1)
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  | apply_depth (Abs (_, _, t)) = apply_depth t
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  | apply_depth _ = 0
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fun is_formula_too_complex ho_atp t =
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  apply_depth t > max_apply_depth orelse formula_has_too_many_lambdas ho_atp [] t
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(* FIXME: Extend to "Meson" and "Metis" *)
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val exists_sledgehammer_const =
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  exists_Const (fn (s, _) => String.isPrefix sledgehammer_prefix s)
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(* FIXME: make more reliable *)
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val exists_low_level_class_const =
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  exists_Const (fn (s, _) =>
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     s = @{const_name equal_class.equal} orelse
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     String.isSubstring (Long_Name.separator ^ "class" ^ Long_Name.separator) s)
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fun is_metastrange_theorem th =
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  case head_of (concl_of th) of
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    Const (s, _) => (s <> @{const_name Trueprop} andalso
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                     s <> @{const_name "=="})
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  | _ => false
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fun is_that_fact th =
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  String.isSuffix (Long_Name.separator ^ Obtain.thatN) (Thm.get_name_hint th)
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  andalso exists_subterm (fn Free (s, _) => s = Name.skolem Auto_Bind.thesisN
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                           | _ => false) (prop_of th)
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fun is_theorem_bad_for_atps ho_atp exporter thm =
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  is_metastrange_theorem thm orelse
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  (not exporter andalso
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   let val t = prop_of thm in
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     is_formula_too_complex ho_atp t orelse exists_type type_has_top_sort t orelse
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     exists_sledgehammer_const t orelse exists_low_level_class_const t orelse
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     is_that_fact thm
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   end)
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fun hackish_string_for_term ctxt t =
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  Print_Mode.setmp (filter (curry (op =) Symbol.xsymbolsN)
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                   (print_mode_value ())) (Syntax.string_of_term ctxt) t
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  |> String.translate (fn c => if Char.isPrint c then str c else "")
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  |> simplify_spaces
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(* This is a terrible hack. Free variables are sometimes coded as "M__" when
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   they are displayed as "M" and we want to avoid clashes with these. But
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   sometimes it's even worse: "Ma__" encodes "M". So we simply reserve all
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   prefixes of all free variables. In the worse case scenario, where the fact
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   won't be resolved correctly, the user can fix it manually, e.g., by naming
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   the fact in question. Ideally we would need nothing of it, but backticks
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   simply don't work with schematic variables. *)
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fun all_prefixes_of s =
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  map (fn i => String.extract (s, 0, SOME i)) (1 upto size s - 1)
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fun close_form t =
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  (t, [] |> Term.add_free_names t |> maps all_prefixes_of)
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  |> fold (fn ((s, i), T) => fn (t', taken) =>
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              let val s' = singleton (Name.variant_list taken) s in
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                ((if fastype_of t' = HOLogic.boolT then HOLogic.all_const
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                  else Logic.all_const) T
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                 $ Abs (s', T, abstract_over (Var ((s, i), T), t')),
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                 s' :: taken)
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              end)
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          (Term.add_vars t [] |> sort_wrt (fst o fst))
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  |> fst
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fun all_facts ctxt ho_atp reserved exporter add_ths chained_ths css_table =
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  let
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    val thy = Proof_Context.theory_of ctxt
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    val global_facts = Global_Theory.facts_of thy
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    val local_facts = Proof_Context.facts_of ctxt
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    val named_locals = local_facts |> Facts.dest_static []
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    val assms = Assumption.all_assms_of ctxt
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    fun is_good_unnamed_local th =
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      not (Thm.has_name_hint th) andalso
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      forall (fn (_, ths) => not (member Thm.eq_thm_prop ths th)) named_locals
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    val unnamed_locals =
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      union Thm.eq_thm_prop (Facts.props local_facts) chained_ths
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      |> filter is_good_unnamed_local |> map (pair "" o single)
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    val full_space =
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      Name_Space.merge (Facts.space_of global_facts, Facts.space_of local_facts)
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    fun add_facts global foldx facts =
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      foldx (fn (name0, ths) =>
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        if not exporter andalso name0 <> "" andalso
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           forall (not o member Thm.eq_thm_prop add_ths) ths andalso
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           (Facts.is_concealed facts name0 orelse
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            (not (Config.get ctxt ignore_no_atp) andalso
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             is_package_def name0) orelse
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            exists (fn s => String.isSuffix s name0)
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                   (multi_base_blacklist ctxt ho_atp)) then
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          I
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        else
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          let
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            val multi = length ths > 1
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            val backquote_thm =
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              backquote o hackish_string_for_term ctxt o close_form o prop_of
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            fun check_thms a =
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              case try (Proof_Context.get_thms ctxt) a of
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                NONE => false
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              | SOME ths' => eq_list Thm.eq_thm_prop (ths, ths')
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          in
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            pair 1
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            #> fold (fn th => fn (j, (multis, unis)) =>
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                        (j + 1,
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                         if not (member Thm.eq_thm_prop add_ths th) andalso
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                            is_theorem_bad_for_atps ho_atp exporter th then
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                           (multis, unis)
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                         else
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                           let
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                             val new =
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                               (((fn () =>
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                                 if name0 = "" then
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                                   th |> backquote_thm
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                                 else
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                                   [Facts.extern ctxt facts name0,
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                                    Name_Space.extern ctxt full_space name0,
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                                    name0]
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                                   |> find_first check_thms
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                                   |> (fn SOME name =>
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                                          make_name reserved multi j name
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                                        | NONE => "")),
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                                stature_of_thm global assms chained_ths
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                                               css_table name0 th), th)
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                           in
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                             if multi then (new :: multis, unis)
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                             else (multis, new :: unis)
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                           end)) ths
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            #> snd
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          end)
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  in
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    (* The single-name theorems go after the multiple-name ones, so that single
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       names are preferred when both are available. *)
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    ([], []) |> add_facts false fold local_facts (unnamed_locals @ named_locals)
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             |> add_facts true Facts.fold_static global_facts global_facts
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             |> op @
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  end
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fun clasimpset_rule_table_of ctxt =
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  let
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    val thy = Proof_Context.theory_of ctxt
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    val atomize = HOLogic.mk_Trueprop o Object_Logic.atomize_term thy
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    fun add stature normalizers get_th =
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      fold (fn rule =>
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               let
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                 val th = rule |> get_th
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                 val t =
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                   th |> Thm.maxidx_of th > 0 ? zero_var_indexes |> prop_of
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               in
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                 fold (fn normalize => Termtab.update (normalize t, stature))
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                      (I :: normalizers)
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               end)
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    val {safeIs, (* safeEs, *) hazIs, (* hazEs, *) ...} =
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      ctxt |> claset_of |> Classical.rep_cs
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    val intros = Item_Net.content safeIs @ Item_Net.content hazIs
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(* Add once it is used:
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    val elims =
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      Item_Net.content safeEs @ Item_Net.content hazEs
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      |> map Classical.classical_rule
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*)
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    val simps = ctxt |> simpset_of |> dest_ss |> #simps
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    val specs = ctxt |> Spec_Rules.get
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    val (rec_defs, nonrec_defs) =
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      specs |> filter (curry (op =) Spec_Rules.Equational o fst)
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            |> maps (snd o snd)
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            |> filter_out (member Thm.eq_thm_prop risky_defs)
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            |> List.partition (is_rec_def o prop_of)
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    val spec_intros =
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      specs |> filter (member (op =) [Spec_Rules.Inductive,
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                                      Spec_Rules.Co_Inductive] o fst)
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            |> maps (snd o snd)
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  in
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    Termtab.empty |> add Simp [atomize] snd simps
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                  |> add Simp [] I rec_defs
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                  |> add Def [] I nonrec_defs
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(* Add once it is used:
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                  |> add Elim [] I elims
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*)
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                  |> add Intro [] I intros
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                  |> add Inductive [] I spec_intros
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  end
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fun uniquify xs =
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  Termtab.fold (cons o snd)
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               (fold (Termtab.update o `(prop_of o snd)) xs Termtab.empty) []
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fun struct_induct_rule_on th =
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  case Logic.strip_horn (prop_of th) of
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    (prems, @{const Trueprop}
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            $ ((p as Var ((p_name, 0), _)) $ (a as Var (_, ind_T)))) =>
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    if not (is_TVar ind_T) andalso length prems > 1 andalso
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       exists (exists_subterm (curry (op aconv) p)) prems andalso
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       not (exists (exists_subterm (curry (op aconv) a)) prems) then
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      SOME (p_name, ind_T)
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    else
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      NONE
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  | _ => NONE
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fun instantiate_induct_rule ctxt concl_prop p_name ((name, stature), th) ind_x =
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  let
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    fun varify_noninducts (t as Free (s, T)) =
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        if (s, T) = ind_x orelse can dest_funT T then t else Var ((s, 0), T)
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      | varify_noninducts t = t
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    val p_inst =
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      concl_prop |> map_aterms varify_noninducts |> close_form
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                 |> lambda (Free ind_x)
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                 |> hackish_string_for_term ctxt
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  in
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    ((fn () => name () ^ "[where " ^ p_name ^ " = " ^ quote p_inst ^ "]",
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      stature), th |> read_instantiate ctxt [((p_name, 0), p_inst)])
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  end
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fun type_match thy (T1, T2) =
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  (Sign.typ_match thy (T2, T1) Vartab.empty; true)
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  handle Type.TYPE_MATCH => false
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fun instantiate_if_induct_rule ctxt stmt stmt_xs (ax as (_, th)) =
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  case struct_induct_rule_on th of
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    SOME (p_name, ind_T) =>
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    let val thy = Proof_Context.theory_of ctxt in
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      stmt_xs |> filter (fn (_, T) => type_match thy (T, ind_T))
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              |> map_filter (try (instantiate_induct_rule ctxt stmt p_name ax))
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    end
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  | NONE => [ax]
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fun external_frees t =
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  [] |> Term.add_frees t |> filter_out (can Name.dest_internal o fst)
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fun maybe_instantiate_inducts ctxt hyp_ts concl_t =
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  if Config.get ctxt instantiate_inducts then
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    let
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      val thy = Proof_Context.theory_of ctxt
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      val ind_stmt =
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        (hyp_ts |> filter_out (null o external_frees), concl_t)
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        |> Logic.list_implies |> Object_Logic.atomize_term thy
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      val ind_stmt_xs = external_frees ind_stmt
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    in maps (instantiate_if_induct_rule ctxt ind_stmt ind_stmt_xs) end
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  else
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    I
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fun maybe_filter_no_atps ctxt =
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  not (Config.get ctxt ignore_no_atp) ? filter_out (No_ATPs.member ctxt o snd)
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fun nearly_all_facts ctxt ho_atp ({add, only, ...} : relevance_override)
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                     chained_ths hyp_ts concl_t =
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  if only andalso null add then
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    []
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  else
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    let
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      val reserved = reserved_isar_keyword_table ()
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      val add_ths = Attrib.eval_thms ctxt add
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      val css_table = clasimpset_rule_table_of ctxt
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    in
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      (if only then
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         maps (map (fn ((name, stature), th) => ((K name, stature), th))
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               o fact_from_ref ctxt reserved chained_ths css_table) add
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       else
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         all_facts ctxt ho_atp reserved false add_ths chained_ths css_table)
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      |> maybe_instantiate_inducts ctxt hyp_ts concl_t
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      |> not only ? maybe_filter_no_atps ctxt
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      |> uniquify
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    end
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end;