paulson@19208
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(* Authors: Jia Meng, NICTA and Lawrence C Paulson, Cambridge University Computer Laboratory
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paulson@19208
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ID: $Id$
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paulson@19208
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Filtering strategies *)
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paulson@19208
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mengj@18791
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structure ReduceAxiomsN =
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mengj@18791
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struct
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mengj@18791
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paulson@19315
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val pass_mark = ref 0.6;
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paulson@19337
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val convergence = ref 2.4; (*Higher numbers allow longer inference chains*)
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paulson@19337
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val follow_defs = ref true; (*Follow definitions. Makes problems bigger.*)
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mengj@18791
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paulson@19337
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fun log_weight2 (x:real) = 1.0 + 2.0/Math.ln (x+1.0);
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paulson@19337
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paulson@19337
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(*The default seems best in practice. A constant function of one ignores
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paulson@19337
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the constant frequencies.*)
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paulson@19337
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val weight_fn = ref log_weight2;
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paulson@19334
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mengj@18791
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paulson@19231
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(*Including equality in this list might be expected to stop rules like subset_antisym from
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paulson@19231
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being chosen, but for some reason filtering works better with them listed.*)
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paulson@19208
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val standard_consts =
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paulson@19315
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["Trueprop","==>","all","Ex","op &","op |","Not","All","op -->",
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paulson@19315
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"op =","==","True","False"];
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mengj@18791
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mengj@18791
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mengj@19009
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(*** constants with types ***)
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mengj@19009
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paulson@19231
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(*An abstraction of Isabelle types*)
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mengj@19009
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datatype const_typ = CTVar | CType of string * const_typ list
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mengj@19009
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paulson@19208
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fun uni_type (CType(con1,args1)) (CType(con2,args2)) = con1=con2 andalso uni_types args1 args2
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paulson@19208
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| uni_type (CType _) CTVar = true
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mengj@19009
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| uni_type CTVar CTVar = true
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mengj@19009
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| uni_type CTVar _ = false
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paulson@19208
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and uni_types [] [] = true
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paulson@19208
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| uni_types (a1::as1) (a2::as2) = uni_type a1 a2 andalso uni_types as1 as2;
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mengj@19009
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paulson@20132
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(*Is there a unifiable constant?*)
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paulson@20132
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fun uni_mem gctab (c,c_typ) =
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paulson@20132
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case Symtab.lookup gctab c of
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NONE => false
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| SOME ctyps_list => exists (uni_types c_typ) ctyps_list;
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paulson@20132
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mengj@19009
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paulson@19231
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fun const_typ_of (Type (c,typs)) = CType (c, map const_typ_of typs)
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paulson@19231
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| const_typ_of (TFree _) = CTVar
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paulson@19231
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| const_typ_of (TVar _) = CTVar
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mengj@19009
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mengj@19009
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paulson@19315
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fun const_with_typ thy (c,typ) =
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let val tvars = Sign.const_typargs thy (c,typ)
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in (c, map const_typ_of tvars) end
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paulson@19315
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handle TYPE _ => (c,[]); (*Variable (locale constant): monomorphic*)
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mengj@19009
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paulson@20132
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fun add_const_typ_table ((c,ctyps), tab) =
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case Symtab.lookup tab c of
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NONE => Symtab.update (c, [ctyps]) tab
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| SOME [] => tab (*ignore!*)
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| SOME ctyps_list => Symtab.update (c, ctyps ins ctyps_list) tab;
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paulson@20132
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paulson@19315
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(*Free variables are counted, as well as constants, to handle locales*)
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paulson@20132
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fun add_term_consts_typs_rm thy (Const(c, typ), tab) =
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add_const_typ_table (const_with_typ thy (c,typ), tab)
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paulson@20132
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| add_term_consts_typs_rm thy (Free(c, typ), tab) =
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add_const_typ_table (const_with_typ thy (c,typ), tab)
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| add_term_consts_typs_rm thy (t $ u, tab) =
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add_term_consts_typs_rm thy (t, add_term_consts_typs_rm thy (u, tab))
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paulson@20132
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| add_term_consts_typs_rm thy (Abs(_,_,t), tab) = add_term_consts_typs_rm thy (t, tab)
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paulson@20132
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| add_term_consts_typs_rm thy (_, tab) = tab;
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mengj@19009
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paulson@20132
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(*The empty list here indicates that the constant is being ignored*)
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paulson@20132
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fun add_standard_const (s,tab) = Symtab.update (s,[]) tab;
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mengj@19009
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paulson@20132
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val null_const_tab : const_typ list list Symtab.table =
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paulson@20132
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foldl add_standard_const Symtab.empty standard_consts;
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paulson@20132
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paulson@20132
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fun get_goal_consts_typs thy cs = foldl (add_term_consts_typs_rm thy) null_const_tab cs;
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mengj@19009
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paulson@19212
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paulson@19231
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(**** Constant / Type Frequencies ****)
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paulson@19212
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paulson@19231
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local
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paulson@19231
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paulson@19231
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fun cons_nr CTVar = 0
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paulson@19231
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| cons_nr (CType _) = 1;
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paulson@19231
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paulson@19231
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in
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paulson@19231
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paulson@19231
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fun const_typ_ord TU =
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paulson@19231
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case TU of
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paulson@19231
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(CType (a, Ts), CType (b, Us)) =>
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paulson@19231
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(case fast_string_ord(a,b) of EQUAL => dict_ord const_typ_ord (Ts,Us) | ord => ord)
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paulson@19231
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| (T, U) => int_ord (cons_nr T, cons_nr U);
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paulson@19231
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paulson@19231
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end;
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paulson@19231
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paulson@19231
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structure CTtab = TableFun(type key = const_typ list val ord = dict_ord const_typ_ord);
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paulson@19231
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mengj@19355
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fun count_axiom_consts thy ((thm,_), tab) =
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paulson@19315
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let fun count_const (a, T, tab) =
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paulson@19315
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let val (c, cts) = const_with_typ thy (a,T)
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paulson@19315
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val cttab = Option.getOpt (Symtab.lookup tab c, CTtab.empty)
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paulson@19315
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val n = Option.getOpt (CTtab.lookup cttab cts, 0)
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paulson@19315
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in
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Symtab.update (c, CTtab.update (cts, n+1) cttab) tab
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end
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paulson@19315
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fun count_term_consts (Const(a,T), tab) = count_const(a,T,tab)
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paulson@19315
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| count_term_consts (Free(a,T), tab) = count_const(a,T,tab)
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paulson@19231
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| count_term_consts (t $ u, tab) =
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paulson@19231
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count_term_consts (t, count_term_consts (u, tab))
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paulson@19231
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| count_term_consts (Abs(_,_,t), tab) = count_term_consts (t, tab)
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paulson@19231
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| count_term_consts (_, tab) = tab
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mengj@19355
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in count_term_consts (prop_of thm, tab) end;
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paulson@19212
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mengj@19009
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mengj@19009
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(******** filter clauses ********)
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mengj@19009
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paulson@19231
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fun const_weight ctab (c, cts) =
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paulson@19231
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let val pairs = CTtab.dest (Option.valOf (Symtab.lookup ctab c))
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paulson@19231
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fun add ((cts',m), n) = if uni_types cts cts' then m+n else n
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paulson@19231
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in List.foldl add 0 pairs end;
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paulson@19231
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paulson@19231
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fun add_ct_weight ctab ((c,T), w) =
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paulson@19231
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w + !weight_fn (real (const_weight ctab (c,T)));
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paulson@19212
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paulson@19212
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fun consts_typs_weight ctab =
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paulson@19212
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List.foldl (add_ct_weight ctab) 0.0;
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paulson@19212
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paulson@19231
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(*Relevant constants are weighted according to frequency,
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paulson@19231
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but irrelevant constants are simply counted. Otherwise, Skolem functions,
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which are rare, would harm a clause's chances of being picked.*)
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paulson@19315
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fun clause_weight ctab gctyps consts_typs =
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paulson@20132
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let val rel = filter (uni_mem gctyps) consts_typs
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paulson@19231
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val rel_weight = consts_typs_weight ctab rel
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mengj@19009
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in
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paulson@19231
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rel_weight / (rel_weight + real (length consts_typs - length rel))
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mengj@19009
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end;
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paulson@19315
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paulson@20132
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fun add_consts_with_typs (c,[]) cpairs = cpairs
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paulson@20132
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| add_consts_with_typs (c, ctyps_list) cpairs =
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foldl (fn (ctyps,cpairs) => (c,ctyps)::cpairs) cpairs ctyps_list;
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paulson@20132
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paulson@20132
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fun consts_typs_of_term thy t =
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paulson@20132
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let val tab = add_term_consts_typs_rm thy (t, null_const_tab)
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paulson@20132
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in Symtab.fold add_consts_with_typs tab [] end;
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paulson@20132
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mengj@19355
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fun pair_consts_typs_axiom thy (thm,name) =
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mengj@19355
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((thm,name), (consts_typs_of_term thy (prop_of thm)));
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mengj@19009
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paulson@19321
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exception ConstFree;
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paulson@19321
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fun dest_ConstFree (Const aT) = aT
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paulson@19321
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| dest_ConstFree (Free aT) = aT
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paulson@19321
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| dest_ConstFree _ = raise ConstFree;
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paulson@19321
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paulson@19321
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(*Look for definitions of the form f ?x1 ... ?xn = t, but not reversed.*)
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mengj@19355
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fun defines thy (thm,(name,n)) gctypes =
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mengj@19355
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let val tm = prop_of thm
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paulson@19448
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fun defs lhs rhs =
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paulson@19448
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let val (rator,args) = strip_comb lhs
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mengj@19355
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val ct = const_with_typ thy (dest_ConstFree rator)
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paulson@20132
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in forall is_Var args andalso
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paulson@20132
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term_varnames rhs subset term_varnames lhs andalso
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paulson@20132
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uni_mem gctypes ct
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paulson@19448
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end
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paulson@19448
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handle ConstFree => false
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mengj@19355
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in
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paulson@19448
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case tm of Const ("Trueprop",_) $ (Const("op =",_) $ lhs $ rhs) =>
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paulson@19448
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defs lhs rhs andalso
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mengj@19355
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(Output.debug ("Definition found: " ^ name ^ "_" ^ Int.toString n); true)
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mengj@19355
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| _ => false
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paulson@20132
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end;
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paulson@19321
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paulson@19337
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fun relevant_clauses thy ctab p rel_consts =
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paulson@19337
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let fun relevant (newrels,rejects) [] =
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paulson@19337
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if null newrels then []
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paulson@19337
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else
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paulson@20132
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let val new_consts = List.concat (map #2 newrels)
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paulson@20132
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val rel_consts' = foldl add_const_typ_table rel_consts new_consts
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paulson@19337
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val newp = p + (1.0-p) / !convergence
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paulson@19337
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in Output.debug ("found relevant: " ^ Int.toString (length newrels));
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paulson@19337
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newrels @ relevant_clauses thy ctab newp rel_consts' rejects
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paulson@19337
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end
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mengj@19355
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| relevant (newrels,rejects) ((ax as (clsthm,consts_typs)) :: axs) =
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paulson@19337
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let val weight = clause_weight ctab rel_consts consts_typs
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paulson@19337
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in
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mengj@19355
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if p <= weight orelse (!follow_defs andalso defines thy clsthm rel_consts)
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paulson@19337
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then relevant (ax::newrels, rejects) axs
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paulson@19337
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else relevant (newrels, ax::rejects) axs
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paulson@19337
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end
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paulson@19337
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in Output.debug ("relevant_clauses: " ^ Real.toString p);
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paulson@19337
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relevant ([],[]) end;
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paulson@19337
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paulson@19337
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paulson@19315
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fun relevance_filter_aux thy axioms goals =
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paulson@19315
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let val const_tab = List.foldl (count_axiom_consts thy) Symtab.empty axioms
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paulson@19231
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val goals_consts_typs = get_goal_consts_typs thy goals
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paulson@19337
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val rels = relevant_clauses thy const_tab (!pass_mark) goals_consts_typs
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paulson@19334
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(map (pair_consts_typs_axiom thy) axioms)
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paulson@19231
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in
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paulson@19334
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Output.debug ("Total relevant: " ^ Int.toString (length rels));
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paulson@19334
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rels
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paulson@19231
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end;
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mengj@19009
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paulson@19315
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fun relevance_filter thy axioms goals =
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paulson@19337
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if !pass_mark < 0.1 then axioms
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paulson@19337
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else map #1 (relevance_filter_aux thy axioms goals);
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mengj@19009
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mengj@18791
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mengj@18791
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end; |