src/HOL/Tools/Sledgehammer/sledgehammer_fact_preprocessor.ML
author blanchet
Fri Apr 16 15:49:13 2010 +0200 (2010-04-16)
changeset 36170 0cdb76723c88
parent 36106 19deea200358
child 36228 df47dc6c0e03
permissions -rw-r--r--
added original constant names to Sledgehammer internal terms + output short names if "debug" is set (for increased readability)
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(*  Title:      HOL/Tools/Sledgehammer/sledgehammer_fact_preprocessor.ML
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    Author:     Jia Meng, Cambridge University Computer Laboratory
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Transformation of axiom rules (elim/intro/etc) into CNF forms.
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*)
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signature SLEDGEHAMMER_FACT_PREPROCESSOR =
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sig
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  val trace: bool Unsynchronized.ref
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  val trace_msg: (unit -> string) -> unit
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  val skolem_prefix: string
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  val cnf_axiom: theory -> thm -> thm list
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  val pairname: thm -> string * thm
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  val multi_base_blacklist: string list
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  val bad_for_atp: thm -> bool
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  val type_has_topsort: typ -> bool
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  val cnf_rules_pairs: theory -> (string * thm) list -> (thm * (string * int)) list
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  val neg_clausify: thm list -> thm list
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  val combinators: thm -> thm
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  val neg_conjecture_clauses: Proof.context -> thm -> int -> thm list * (string * typ) list
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  val suppress_endtheory: bool Unsynchronized.ref
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    (*for emergency use where endtheory causes problems*)
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  val setup: theory -> theory
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end;
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structure Sledgehammer_Fact_Preprocessor : SLEDGEHAMMER_FACT_PREPROCESSOR =
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struct
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open Sledgehammer_FOL_Clause
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val trace = Unsynchronized.ref false;
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fun trace_msg msg = if !trace then tracing (msg ()) else ();
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val skolem_prefix = "sko_"
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fun freeze_thm th = #1 (Drule.legacy_freeze_thaw th);
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val type_has_topsort = Term.exists_subtype
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  (fn TFree (_, []) => true
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    | TVar (_, []) => true
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    | _ => false);
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(**** Transformation of Elimination Rules into First-Order Formulas****)
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val cfalse = cterm_of @{theory HOL} HOLogic.false_const;
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val ctp_false = cterm_of @{theory HOL} (HOLogic.mk_Trueprop HOLogic.false_const);
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(*Converts an elim-rule into an equivalent theorem that does not have the
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  predicate variable.  Leaves other theorems unchanged.  We simply instantiate the
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  conclusion variable to False.*)
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fun transform_elim th =
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  case concl_of th of    (*conclusion variable*)
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       @{const Trueprop} $ (v as Var (_, @{typ bool})) =>
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           Thm.instantiate ([], [(cterm_of @{theory HOL} v, cfalse)]) th
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    | v as Var(_, @{typ prop}) =>
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           Thm.instantiate ([], [(cterm_of @{theory HOL} v, ctp_false)]) th
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    | _ => th;
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(*To enforce single-threading*)
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exception Clausify_failure of theory;
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(**** SKOLEMIZATION BY INFERENCE (lcp) ****)
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fun rhs_extra_types lhsT rhs =
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  let val lhs_vars = Term.add_tfreesT lhsT []
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      fun add_new_TFrees (TFree v) =
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            if member (op =) lhs_vars v then I else insert (op =) (TFree v)
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        | add_new_TFrees _ = I
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      val rhs_consts = fold_aterms (fn Const c => insert (op =) c | _ => I) rhs []
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  in fold (#2 #> Term.fold_atyps add_new_TFrees) rhs_consts [] end;
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(*Traverse a theorem, declaring Skolem function definitions. String s is the suggested
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  prefix for the Skolem constant.*)
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fun declare_skofuns s th =
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  let
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    val nref = Unsynchronized.ref 0    (* FIXME ??? *)
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    fun dec_sko (Const (@{const_name Ex}, _) $ (xtp as Abs (_, T, p))) (axs, thy) =
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          (*Existential: declare a Skolem function, then insert into body and continue*)
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          let
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            val cname = skolem_prefix ^ s ^ "_" ^ Int.toString (Unsynchronized.inc nref)
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            val args0 = OldTerm.term_frees xtp  (*get the formal parameter list*)
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            val Ts = map type_of args0
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            val extraTs = rhs_extra_types (Ts ---> T) xtp
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            val argsx = map (fn T => Free (gensym "vsk", T)) extraTs
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            val args = argsx @ args0
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            val cT = extraTs ---> Ts ---> T
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            val rhs = list_abs_free (map dest_Free args, HOLogic.choice_const T $ xtp)
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                    (*Forms a lambda-abstraction over the formal parameters*)
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            val (c, thy') =
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              Sign.declare_const ((Binding.conceal (Binding.name cname), cT), NoSyn) thy
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            val cdef = cname ^ "_def"
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            val ((_, ax), thy'') =
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              Thm.add_def true false (Binding.name cdef, Logic.mk_equals (c, rhs)) thy'
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            val ax' = Drule.export_without_context ax
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          in dec_sko (subst_bound (list_comb (c, args), p)) (ax' :: axs, thy'') end
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      | dec_sko (Const (@{const_name All}, _) $ (Abs (a, T, p))) thx =
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          (*Universal quant: insert a free variable into body and continue*)
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          let val fname = Name.variant (OldTerm.add_term_names (p, [])) a
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          in dec_sko (subst_bound (Free (fname, T), p)) thx end
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      | dec_sko (@{const "op &"} $ p $ q) thx = dec_sko q (dec_sko p thx)
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      | dec_sko (@{const "op |"} $ p $ q) thx = dec_sko q (dec_sko p thx)
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      | dec_sko (@{const Trueprop} $ p) thx = dec_sko p thx
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      | dec_sko t thx = thx (*Do nothing otherwise*)
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  in fn thy => dec_sko (Thm.prop_of th) ([], thy) end;
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(*Traverse a theorem, accumulating Skolem function definitions.*)
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fun assume_skofuns s th =
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  let val sko_count = Unsynchronized.ref 0   (* FIXME ??? *)
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      fun dec_sko (Const (@{const_name Ex}, _) $ (xtp as Abs(_,T,p))) defs =
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            (*Existential: declare a Skolem function, then insert into body and continue*)
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            let val skos = map (#1 o Logic.dest_equals) defs  (*existing sko fns*)
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                val args = subtract (op =) skos (OldTerm.term_frees xtp) (*the formal parameters*)
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                val Ts = map type_of args
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                val cT = Ts ---> T
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                val id = skolem_prefix ^ s ^ "_" ^ Int.toString (Unsynchronized.inc sko_count)
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                val c = Free (id, cT)
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                val rhs = list_abs_free (map dest_Free args,
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                                         HOLogic.choice_const T $ xtp)
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                      (*Forms a lambda-abstraction over the formal parameters*)
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                val def = Logic.mk_equals (c, rhs)
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            in dec_sko (subst_bound (list_comb(c,args), p))
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                       (def :: defs)
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            end
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        | dec_sko (Const (@{const_name All},_) $ Abs (a, T, p)) defs =
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            (*Universal quant: insert a free variable into body and continue*)
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            let val fname = Name.variant (OldTerm.add_term_names (p,[])) a
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            in dec_sko (subst_bound (Free(fname,T), p)) defs end
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        | dec_sko (@{const "op &"} $ p $ q) defs = dec_sko q (dec_sko p defs)
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        | dec_sko (@{const "op |"} $ p $ q) defs = dec_sko q (dec_sko p defs)
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        | dec_sko (@{const Trueprop} $ p) defs = dec_sko p defs
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        | dec_sko t defs = defs (*Do nothing otherwise*)
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  in  dec_sko (prop_of th) []  end;
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(**** REPLACING ABSTRACTIONS BY COMBINATORS ****)
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(*Returns the vars of a theorem*)
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fun vars_of_thm th =
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  map (Thm.cterm_of (theory_of_thm th) o Var) (Thm.fold_terms Term.add_vars th []);
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(*Make a version of fun_cong with a given variable name*)
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local
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    val fun_cong' = fun_cong RS asm_rl; (*renumber f, g to prevent clashes with (a,0)*)
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    val cx = hd (vars_of_thm fun_cong');
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    val ty = typ_of (ctyp_of_term cx);
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    val thy = theory_of_thm fun_cong;
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    fun mkvar a = cterm_of thy (Var((a,0),ty));
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in
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fun xfun_cong x = Thm.instantiate ([], [(cx, mkvar x)]) fun_cong'
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end;
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(*Removes the lambdas from an equation of the form t = (%x. u).  A non-negative n,
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  serves as an upper bound on how many to remove.*)
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fun strip_lambdas 0 th = th
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  | strip_lambdas n th =
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      case prop_of th of
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          _ $ (Const (@{const_name "op ="}, _) $ _ $ Abs (x, _, _)) =>
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              strip_lambdas (n-1) (freeze_thm (th RS xfun_cong x))
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        | _ => th;
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val lambda_free = not o Term.has_abs;
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val [f_B,g_B] = map (cterm_of @{theory}) (OldTerm.term_vars (prop_of @{thm abs_B}));
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val [g_C,f_C] = map (cterm_of @{theory}) (OldTerm.term_vars (prop_of @{thm abs_C}));
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val [f_S,g_S] = map (cterm_of @{theory}) (OldTerm.term_vars (prop_of @{thm abs_S}));
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(*FIXME: requires more use of cterm constructors*)
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fun abstract ct =
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  let
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      val thy = theory_of_cterm ct
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      val Abs(x,_,body) = term_of ct
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      val Type(@{type_name fun}, [xT,bodyT]) = typ_of (ctyp_of_term ct)
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      val cxT = ctyp_of thy xT and cbodyT = ctyp_of thy bodyT
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      fun makeK() = instantiate' [SOME cxT, SOME cbodyT] [SOME (cterm_of thy body)] @{thm abs_K}
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  in
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      case body of
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          Const _ => makeK()
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        | Free _ => makeK()
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        | Var _ => makeK()  (*though Var isn't expected*)
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        | Bound 0 => instantiate' [SOME cxT] [] @{thm abs_I} (*identity: I*)
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        | rator$rand =>
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            if loose_bvar1 (rator,0) then (*C or S*)
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               if loose_bvar1 (rand,0) then (*S*)
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                 let val crator = cterm_of thy (Abs(x,xT,rator))
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                     val crand = cterm_of thy (Abs(x,xT,rand))
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                     val abs_S' = cterm_instantiate [(f_S,crator),(g_S,crand)] @{thm abs_S}
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                     val (_,rhs) = Thm.dest_equals (cprop_of abs_S')
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                 in
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                   Thm.transitive abs_S' (Conv.binop_conv abstract rhs)
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                 end
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               else (*C*)
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                 let val crator = cterm_of thy (Abs(x,xT,rator))
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                     val abs_C' = cterm_instantiate [(f_C,crator),(g_C,cterm_of thy rand)] @{thm abs_C}
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                     val (_,rhs) = Thm.dest_equals (cprop_of abs_C')
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                 in
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                   Thm.transitive abs_C' (Conv.fun_conv (Conv.arg_conv abstract) rhs)
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                 end
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            else if loose_bvar1 (rand,0) then (*B or eta*)
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               if rand = Bound 0 then eta_conversion ct
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               else (*B*)
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                 let val crand = cterm_of thy (Abs(x,xT,rand))
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                     val crator = cterm_of thy rator
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                     val abs_B' = cterm_instantiate [(f_B,crator),(g_B,crand)] @{thm abs_B}
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                     val (_,rhs) = Thm.dest_equals (cprop_of abs_B')
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                 in
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                   Thm.transitive abs_B' (Conv.arg_conv abstract rhs)
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                 end
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            else makeK()
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        | _ => error "abstract: Bad term"
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  end;
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(*Traverse a theorem, declaring abstraction function definitions. String s is the suggested
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  prefix for the constants.*)
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fun combinators_aux ct =
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  if lambda_free (term_of ct) then reflexive ct
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  else
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  case term_of ct of
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      Abs _ =>
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        let val (cv, cta) = Thm.dest_abs NONE ct
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            val (v, _) = dest_Free (term_of cv)
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            val u_th = combinators_aux cta
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            val cu = Thm.rhs_of u_th
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            val comb_eq = abstract (Thm.cabs cv cu)
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        in transitive (abstract_rule v cv u_th) comb_eq end
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    | _ $ _ =>
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        let val (ct1, ct2) = Thm.dest_comb ct
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        in  combination (combinators_aux ct1) (combinators_aux ct2)  end;
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fun combinators th =
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  if lambda_free (prop_of th) then th
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  else
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    let val th = Drule.eta_contraction_rule th
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        val eqth = combinators_aux (cprop_of th)
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    in  equal_elim eqth th   end
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    handle THM (msg,_,_) =>
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      (warning (cat_lines
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        ["Error in the combinator translation of " ^ Display.string_of_thm_without_context th,
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          "  Exception message: " ^ msg]);
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       TrueI);  (*A type variable of sort {} will cause make abstraction fail.*)
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(*cterms are used throughout for efficiency*)
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val cTrueprop = Thm.cterm_of @{theory HOL} HOLogic.Trueprop;
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(*cterm version of mk_cTrueprop*)
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fun c_mkTrueprop A = Thm.capply cTrueprop A;
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(*Given an abstraction over n variables, replace the bound variables by free
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  ones. Return the body, along with the list of free variables.*)
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fun c_variant_abs_multi (ct0, vars) =
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      let val (cv,ct) = Thm.dest_abs NONE ct0
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      in  c_variant_abs_multi (ct, cv::vars)  end
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      handle CTERM _ => (ct0, rev vars);
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(*Given the definition of a Skolem function, return a theorem to replace
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  an existential formula by a use of that function.
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   Example: "EX x. x : A & x ~: B ==> sko A B : A & sko A B ~: B"  [.] *)
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fun skolem_of_def def =
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  let val (c,rhs) = Thm.dest_equals (cprop_of (freeze_thm def))
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      val (ch, frees) = c_variant_abs_multi (rhs, [])
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      val (chilbert,cabs) = Thm.dest_comb ch
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      val thy = Thm.theory_of_cterm chilbert
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      val t = Thm.term_of chilbert
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      val T = case t of
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                Const (@{const_name Eps}, Type (@{type_name fun},[_,T])) => T
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              | _ => raise THM ("skolem_of_def: expected Eps", 0, [def])
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      val cex = Thm.cterm_of thy (HOLogic.exists_const T)
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      val ex_tm = c_mkTrueprop (Thm.capply cex cabs)
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      and conc =  c_mkTrueprop (Drule.beta_conv cabs (Drule.list_comb(c,frees)));
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      fun tacf [prem] = rewrite_goals_tac [def] THEN rtac (prem RS @{thm someI_ex}) 1
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  in  Goal.prove_internal [ex_tm] conc tacf
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       |> forall_intr_list frees
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       |> Thm.forall_elim_vars 0  (*Introduce Vars, but don't discharge defs.*)
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       |> Thm.varifyT_global
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  end;
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(*Converts an Isabelle theorem (intro, elim or simp format, even higher-order) into NNF.*)
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fun to_nnf th ctxt0 =
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  let val th1 = th |> transform_elim |> zero_var_indexes
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      val ((_, [th2]), ctxt) = Variable.import true [th1] ctxt0
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      val th3 = th2
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        |> Conv.fconv_rule Object_Logic.atomize
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        |> Meson.make_nnf ctxt |> strip_lambdas ~1
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   286
  in  (th3, ctxt)  end;
paulson@16009
   287
paulson@18141
   288
(*Generate Skolem functions for a theorem supplied in nnf*)
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   289
fun assume_skolem_of_def s th =
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   290
  map (skolem_of_def o assume o (cterm_of (theory_of_thm th))) (assume_skofuns s th);
paulson@18141
   291
paulson@25007
   292
blanchet@35963
   293
(*** Blacklisting (FIXME: duplicated in "Sledgehammer_Fact_Filter"?) ***)
paulson@25007
   294
paulson@25007
   295
val max_lambda_nesting = 3;
wenzelm@27184
   296
paulson@25007
   297
fun excessive_lambdas (f$t, k) = excessive_lambdas (f,k) orelse excessive_lambdas (t,k)
paulson@25007
   298
  | excessive_lambdas (Abs(_,_,t), k) = k=0 orelse excessive_lambdas (t,k-1)
paulson@25007
   299
  | excessive_lambdas _ = false;
paulson@25007
   300
paulson@25007
   301
fun is_formula_type T = (T = HOLogic.boolT orelse T = propT);
paulson@25007
   302
paulson@25007
   303
(*Don't count nested lambdas at the level of formulas, as they are quantifiers*)
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   304
fun excessive_lambdas_fm Ts (Abs(_,T,t)) = excessive_lambdas_fm (T::Ts) t
paulson@25007
   305
  | excessive_lambdas_fm Ts t =
paulson@25007
   306
      if is_formula_type (fastype_of1 (Ts, t))
paulson@25007
   307
      then exists (excessive_lambdas_fm Ts) (#2 (strip_comb t))
paulson@25007
   308
      else excessive_lambdas (t, max_lambda_nesting);
paulson@25007
   309
wenzelm@33027
   310
(*The max apply_depth of any metis call in Metis_Examples (on 31-10-2007) was 11.*)
paulson@25256
   311
val max_apply_depth = 15;
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   312
paulson@25256
   313
fun apply_depth (f$t) = Int.max (apply_depth f, apply_depth t + 1)
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   314
  | apply_depth (Abs(_,_,t)) = apply_depth t
paulson@25256
   315
  | apply_depth _ = 0;
paulson@25256
   316
wenzelm@27184
   317
fun too_complex t =
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   318
  apply_depth t > max_apply_depth orelse
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   319
  Meson.too_many_clauses NONE t orelse
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   320
  excessive_lambdas_fm [] t;
wenzelm@27184
   321
paulson@25243
   322
fun is_strange_thm th =
paulson@25243
   323
  case head_of (concl_of th) of
blanchet@35963
   324
      Const (a, _) => (a <> @{const_name Trueprop} andalso
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   325
                       a <> @{const_name "=="})
paulson@25243
   326
    | _ => false;
paulson@25243
   327
wenzelm@27184
   328
fun bad_for_atp th =
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   329
  too_complex (prop_of th)
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   330
  orelse exists_type type_has_topsort (prop_of th)
paulson@25761
   331
  orelse is_strange_thm th;
paulson@25243
   332
blanchet@35963
   333
(* FIXME: put other record thms here, or declare as "no_atp" *)
paulson@25007
   334
val multi_base_blacklist =
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   335
  ["defs", "select_defs", "update_defs", "induct", "inducts", "split", "splits",
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   336
   "split_asm", "cases", "ext_cases"];
paulson@25007
   337
paulson@21071
   338
(*Keep the full complexity of the original name*)
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   339
fun flatten_name s = space_implode "_X" (Long_Name.explode s);
paulson@21071
   340
paulson@22731
   341
fun fake_name th =
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   342
  if Thm.has_name_hint th then flatten_name (Thm.get_name_hint th)
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   343
  else gensym "unknown_thm_";
paulson@22731
   344
wenzelm@27184
   345
(*Skolemize a named theorem, with Skolem functions as additional premises.*)
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   346
fun skolem_thm (s, th) =
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   347
  if member (op =) multi_base_blacklist (Long_Name.base_name s) orelse bad_for_atp th then []
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   348
  else
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   349
    let
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   350
      val ctxt0 = Variable.thm_context th
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   351
      val (nnfth, ctxt1) = to_nnf th ctxt0
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   352
      val (cnfs, ctxt2) = Meson.make_cnf (assume_skolem_of_def s nnfth) nnfth ctxt1
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   353
    in  cnfs |> map combinators |> Variable.export ctxt2 ctxt0 |> Meson.finish_cnf  end
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   354
    handle THM _ => [];
wenzelm@27184
   355
paulson@24742
   356
(*The cache prevents repeated clausification of a theorem, and also repeated declaration of
paulson@24742
   357
  Skolem functions.*)
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   358
structure ThmCache = Theory_Data
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   359
(
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   360
  type T = thm list Thmtab.table * unit Symtab.table;
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   361
  val empty = (Thmtab.empty, Symtab.empty);
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   362
  val extend = I;
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   363
  fun merge ((cache1, seen1), (cache2, seen2)) : T =
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   364
    (Thmtab.merge (K true) (cache1, cache2), Symtab.merge (K true) (seen1, seen2));
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   365
);
paulson@22516
   366
wenzelm@27184
   367
val lookup_cache = Thmtab.lookup o #1 o ThmCache.get;
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   368
val already_seen = Symtab.defined o #2 o ThmCache.get;
wenzelm@20461
   369
wenzelm@27184
   370
val update_cache = ThmCache.map o apfst o Thmtab.update;
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   371
fun mark_seen name = ThmCache.map (apsnd (Symtab.update (name, ())));
paulson@25007
   372
wenzelm@20461
   373
(*Exported function to convert Isabelle theorems into axiom clauses*)
wenzelm@27179
   374
fun cnf_axiom thy th0 =
wenzelm@27184
   375
  let val th = Thm.transfer thy th0 in
wenzelm@27184
   376
    case lookup_cache thy th of
wenzelm@27184
   377
      NONE => map Thm.close_derivation (skolem_thm (fake_name th, th))
wenzelm@27184
   378
    | SOME cls => cls
paulson@22516
   379
  end;
paulson@15347
   380
paulson@18141
   381
wenzelm@30291
   382
(**** Rules from the context ****)
paulson@15347
   383
wenzelm@27865
   384
fun pairname th = (Thm.get_name_hint th, th);
wenzelm@27184
   385
paulson@15347
   386
paulson@22471
   387
(**** Translate a set of theorems into CNF ****)
paulson@15347
   388
paulson@19894
   389
fun pair_name_cls k (n, []) = []
paulson@19894
   390
  | pair_name_cls k (n, cls::clss) = (cls, (n,k)) :: pair_name_cls (k+1) (n, clss)
wenzelm@20461
   391
wenzelm@27179
   392
fun cnf_rules_pairs_aux _ pairs [] = pairs
wenzelm@27179
   393
  | cnf_rules_pairs_aux thy pairs ((name,th)::ths) =
wenzelm@27179
   394
      let val pairs' = (pair_name_cls 0 (name, cnf_axiom thy th)) @ pairs
blanchet@35826
   395
                       handle THM _ => pairs |
blanchet@35865
   396
                              CLAUSE _ => pairs
wenzelm@27179
   397
      in  cnf_rules_pairs_aux thy pairs' ths  end;
wenzelm@20461
   398
paulson@21290
   399
(*The combination of rev and tail recursion preserves the original order*)
wenzelm@27179
   400
fun cnf_rules_pairs thy l = cnf_rules_pairs_aux thy [] (rev l);
mengj@19353
   401
mengj@19196
   402
blanchet@35865
   403
(**** Convert all facts of the theory into FOL or HOL clauses ****)
paulson@15347
   404
wenzelm@28544
   405
local
wenzelm@28544
   406
wenzelm@28544
   407
fun skolem_def (name, th) thy =
wenzelm@28544
   408
  let val ctxt0 = Variable.thm_context th in
wenzelm@28544
   409
    (case try (to_nnf th) ctxt0 of
wenzelm@28544
   410
      NONE => (NONE, thy)
wenzelm@28544
   411
    | SOME (nnfth, ctxt1) =>
wenzelm@28544
   412
        let val (defs, thy') = declare_skofuns (flatten_name name) nnfth thy
wenzelm@28544
   413
        in (SOME (th, ctxt0, ctxt1, nnfth, defs), thy') end)
wenzelm@28544
   414
  end;
paulson@24742
   415
wenzelm@28544
   416
fun skolem_cnfs (th, ctxt0, ctxt1, nnfth, defs) =
wenzelm@28544
   417
  let
wenzelm@28544
   418
    val (cnfs, ctxt2) = Meson.make_cnf (map skolem_of_def defs) nnfth ctxt1;
wenzelm@28544
   419
    val cnfs' = cnfs
wenzelm@28544
   420
      |> map combinators
wenzelm@28544
   421
      |> Variable.export ctxt2 ctxt0
wenzelm@28544
   422
      |> Meson.finish_cnf
wenzelm@28544
   423
      |> map Thm.close_derivation;
wenzelm@28544
   424
    in (th, cnfs') end;
wenzelm@28544
   425
wenzelm@28544
   426
in
paulson@24742
   427
wenzelm@27184
   428
fun saturate_skolem_cache thy =
wenzelm@28544
   429
  let
wenzelm@33306
   430
    val facts = PureThy.facts_of thy;
wenzelm@33306
   431
    val new_facts = (facts, []) |-> Facts.fold_static (fn (name, ths) =>
wenzelm@33306
   432
      if Facts.is_concealed facts name orelse already_seen thy name then I
wenzelm@33306
   433
      else cons (name, ths));
wenzelm@28544
   434
    val new_thms = (new_facts, []) |-> fold (fn (name, ths) =>
wenzelm@30364
   435
      if member (op =) multi_base_blacklist (Long_Name.base_name name) then I
wenzelm@28544
   436
      else fold_index (fn (i, th) =>
wenzelm@28544
   437
        if bad_for_atp th orelse is_some (lookup_cache thy th) then I
wenzelm@28544
   438
        else cons (name ^ "_" ^ string_of_int (i + 1), Thm.transfer thy th)) ths);
wenzelm@28544
   439
  in
wenzelm@28544
   440
    if null new_facts then NONE
wenzelm@28544
   441
    else
wenzelm@28544
   442
      let
wenzelm@28544
   443
        val (defs, thy') = thy
wenzelm@28544
   444
          |> fold (mark_seen o #1) new_facts
wenzelm@28544
   445
          |> fold_map skolem_def (sort_distinct (Thm.thm_ord o pairself snd) new_thms)
wenzelm@28544
   446
          |>> map_filter I;
wenzelm@29368
   447
        val cache_entries = Par_List.map skolem_cnfs defs;
wenzelm@28544
   448
      in SOME (fold update_cache cache_entries thy') end
wenzelm@28544
   449
  end;
wenzelm@27184
   450
wenzelm@28544
   451
end;
paulson@24854
   452
wenzelm@32740
   453
val suppress_endtheory = Unsynchronized.ref false;
wenzelm@27184
   454
wenzelm@27184
   455
fun clause_cache_endtheory thy =
wenzelm@27184
   456
  if ! suppress_endtheory then NONE
wenzelm@27184
   457
  else saturate_skolem_cache thy;
wenzelm@27184
   458
paulson@20457
   459
paulson@22516
   460
(*The cache can be kept smaller by inspecting the prop of each thm. Can ignore all that are
paulson@22516
   461
  lambda_free, but then the individual theory caches become much bigger.*)
paulson@21071
   462
wenzelm@27179
   463
paulson@21999
   464
(*** Converting a subgoal into negated conjecture clauses. ***)
paulson@21999
   465
wenzelm@32262
   466
fun neg_skolemize_tac ctxt =
wenzelm@35625
   467
  EVERY' [rtac ccontr, Object_Logic.atomize_prems_tac, Meson.skolemize_tac ctxt];
paulson@22471
   468
blanchet@35869
   469
val neg_clausify =
blanchet@35869
   470
  Meson.make_clauses_unsorted #> map combinators #> Meson.finish_cnf;
paulson@21999
   471
wenzelm@32257
   472
fun neg_conjecture_clauses ctxt st0 n =
wenzelm@32257
   473
  let
wenzelm@32262
   474
    val st = Seq.hd (neg_skolemize_tac ctxt n st0)
wenzelm@32257
   475
    val ({params, prems, ...}, _) = Subgoal.focus (Variable.set_body false ctxt) n st
wenzelm@32257
   476
  in (neg_clausify prems, map (Term.dest_Free o Thm.term_of o #2) params) end;
paulson@21999
   477
wenzelm@24669
   478
(*Conversion of a subgoal to conjecture clauses. Each clause has
paulson@21999
   479
  leading !!-bound universal variables, to express generality. *)
wenzelm@32257
   480
fun neg_clausify_tac ctxt =
wenzelm@32262
   481
  neg_skolemize_tac ctxt THEN'
wenzelm@32257
   482
  SUBGOAL (fn (prop, i) =>
wenzelm@32257
   483
    let val ts = Logic.strip_assums_hyp prop in
wenzelm@32257
   484
      EVERY'
wenzelm@32283
   485
       [Subgoal.FOCUS
wenzelm@32257
   486
         (fn {prems, ...} =>
wenzelm@32257
   487
           (Method.insert_tac
wenzelm@32257
   488
             (map forall_intr_vars (neg_clausify prems)) i)) ctxt,
wenzelm@32257
   489
        REPEAT_DETERM_N (length ts) o etac thin_rl] i
paulson@21999
   490
     end);
paulson@21999
   491
wenzelm@30722
   492
val neg_clausify_setup =
wenzelm@32257
   493
  Method.setup @{binding neg_clausify} (Scan.succeed (SIMPLE_METHOD' o neg_clausify_tac))
wenzelm@30515
   494
  "conversion of goal to conjecture clauses";
wenzelm@24669
   495
wenzelm@27184
   496
wenzelm@27184
   497
(** Attribute for converting a theorem into clauses **)
wenzelm@27184
   498
wenzelm@30722
   499
val clausify_setup =
wenzelm@30722
   500
  Attrib.setup @{binding clausify}
wenzelm@30722
   501
    (Scan.lift OuterParse.nat >>
wenzelm@30722
   502
      (fn i => Thm.rule_attribute (fn context => fn th =>
wenzelm@30722
   503
          Meson.make_meta_clause (nth (cnf_axiom (Context.theory_of context) th) i))))
wenzelm@30722
   504
  "conversion of theorem to clauses";
wenzelm@27184
   505
wenzelm@27184
   506
wenzelm@27184
   507
(** setup **)
wenzelm@27184
   508
wenzelm@27184
   509
val setup =
wenzelm@30722
   510
  neg_clausify_setup #>
wenzelm@30722
   511
  clausify_setup #>
wenzelm@27184
   512
  perhaps saturate_skolem_cache #>
wenzelm@27184
   513
  Theory.at_end clause_cache_endtheory;
paulson@18510
   514
wenzelm@20461
   515
end;