src/HOL/Tools/ATP/atp_translate.ML
author blanchet
Thu, 21 Jul 2011 21:29:10 +0200
changeset 44810 081718c0b0a8
parent 44807 127749bbc639
child 44832 91294d386539
permissions -rw-r--r--
make "concealed" lambda translation sound
     1 (*  Title:      HOL/Tools/ATP/atp_translate.ML
     2     Author:     Fabian Immler, TU Muenchen
     3     Author:     Makarius
     4     Author:     Jasmin Blanchette, TU Muenchen
     5 
     6 Translation of HOL to FOL for Metis and Sledgehammer.
     7 *)
     8 
     9 signature ATP_TRANSLATE =
    10 sig
    11   type ('a, 'b) ho_term = ('a, 'b) ATP_Problem.ho_term
    12   type connective = ATP_Problem.connective
    13   type ('a, 'b, 'c) formula = ('a, 'b, 'c) ATP_Problem.formula
    14   type format = ATP_Problem.format
    15   type formula_kind = ATP_Problem.formula_kind
    16   type 'a problem = 'a ATP_Problem.problem
    17 
    18   datatype locality =
    19     General | Helper | Extensionality | Intro | Elim | Simp | Local | Assum |
    20     Chained
    21 
    22   datatype order = First_Order | Higher_Order
    23   datatype polymorphism = Polymorphic | Monomorphic | Mangled_Monomorphic
    24   datatype type_level =
    25     All_Types | Noninf_Nonmono_Types | Fin_Nonmono_Types | Const_Arg_Types |
    26     No_Types
    27   datatype type_heaviness = Heavyweight | Lightweight
    28 
    29   datatype type_enc =
    30     Simple_Types of order * type_level |
    31     Preds of polymorphism * type_level * type_heaviness |
    32     Tags of polymorphism * type_level * type_heaviness
    33 
    34   val bound_var_prefix : string
    35   val schematic_var_prefix : string
    36   val fixed_var_prefix : string
    37   val tvar_prefix : string
    38   val tfree_prefix : string
    39   val const_prefix : string
    40   val type_const_prefix : string
    41   val class_prefix : string
    42   val polymorphic_free_prefix : string
    43   val skolem_const_prefix : string
    44   val old_skolem_const_prefix : string
    45   val new_skolem_const_prefix : string
    46   val type_decl_prefix : string
    47   val sym_decl_prefix : string
    48   val preds_sym_formula_prefix : string
    49   val lightweight_tags_sym_formula_prefix : string
    50   val fact_prefix : string
    51   val conjecture_prefix : string
    52   val helper_prefix : string
    53   val class_rel_clause_prefix : string
    54   val arity_clause_prefix : string
    55   val tfree_clause_prefix : string
    56   val typed_helper_suffix : string
    57   val untyped_helper_suffix : string
    58   val type_tag_idempotence_helper_name : string
    59   val predicator_name : string
    60   val app_op_name : string
    61   val type_tag_name : string
    62   val type_pred_name : string
    63   val simple_type_prefix : string
    64   val prefixed_predicator_name : string
    65   val prefixed_app_op_name : string
    66   val prefixed_type_tag_name : string
    67   val ascii_of : string -> string
    68   val unascii_of : string -> string
    69   val strip_prefix_and_unascii : string -> string -> string option
    70   val proxy_table : (string * (string * (thm * (string * string)))) list
    71   val proxify_const : string -> (string * string) option
    72   val invert_const : string -> string
    73   val unproxify_const : string -> string
    74   val new_skolem_var_name_from_const : string -> string
    75   val atp_irrelevant_consts : string list
    76   val atp_schematic_consts_of : term -> typ list Symtab.table
    77   val is_locality_global : locality -> bool
    78   val type_enc_from_string : string -> type_enc
    79   val is_type_enc_higher_order : type_enc -> bool
    80   val polymorphism_of_type_enc : type_enc -> polymorphism
    81   val level_of_type_enc : type_enc -> type_level
    82   val is_type_enc_virtually_sound : type_enc -> bool
    83   val is_type_enc_fairly_sound : type_enc -> bool
    84   val choose_format : format list -> type_enc -> format * type_enc
    85   val mk_aconns :
    86     connective -> ('a, 'b, 'c) formula list -> ('a, 'b, 'c) formula
    87   val unmangled_const : string -> string * (string, 'b) ho_term list
    88   val unmangled_const_name : string -> string
    89   val helper_table : ((string * bool) * thm list) list
    90   val factsN : string
    91   val introduce_combinators : Proof.context -> term -> term
    92   val prepare_atp_problem :
    93     Proof.context -> format -> formula_kind -> formula_kind -> type_enc -> bool
    94     -> bool -> (term list -> term list * term list) -> bool -> bool -> term list
    95     -> term -> ((string * locality) * term) list
    96     -> string problem * string Symtab.table * int * int
    97        * (string * locality) list vector * int list * int Symtab.table
    98   val atp_problem_weights : string problem -> (string * real) list
    99 end;
   100 
   101 structure ATP_Translate : ATP_TRANSLATE =
   102 struct
   103 
   104 open ATP_Util
   105 open ATP_Problem
   106 
   107 type name = string * string
   108 
   109 val generate_info = false (* experimental *)
   110 
   111 fun isabelle_info s =
   112   if generate_info then SOME (ATerm ("[]", [ATerm ("isabelle_" ^ s, [])]))
   113   else NONE
   114 
   115 val introN = "intro"
   116 val elimN = "elim"
   117 val simpN = "simp"
   118 
   119 val bound_var_prefix = "B_"
   120 val schematic_var_prefix = "V_"
   121 val fixed_var_prefix = "v_"
   122 val tvar_prefix = "T_"
   123 val tfree_prefix = "t_"
   124 val const_prefix = "c_"
   125 val type_const_prefix = "tc_"
   126 val class_prefix = "cl_"
   127 
   128 val polymorphic_free_prefix = "poly_free"
   129 
   130 val skolem_const_prefix = "ATP" ^ Long_Name.separator ^ "Sko"
   131 val old_skolem_const_prefix = skolem_const_prefix ^ "o"
   132 val new_skolem_const_prefix = skolem_const_prefix ^ "n"
   133 
   134 val type_decl_prefix = "ty_"
   135 val sym_decl_prefix = "sy_"
   136 val preds_sym_formula_prefix = "psy_"
   137 val lightweight_tags_sym_formula_prefix = "tsy_"
   138 val fact_prefix = "fact_"
   139 val conjecture_prefix = "conj_"
   140 val helper_prefix = "help_"
   141 val class_rel_clause_prefix = "clar_"
   142 val arity_clause_prefix = "arity_"
   143 val tfree_clause_prefix = "tfree_"
   144 
   145 val lambda_fact_prefix = "ATP.lambda_"
   146 val typed_helper_suffix = "_T"
   147 val untyped_helper_suffix = "_U"
   148 val type_tag_idempotence_helper_name = helper_prefix ^ "ti_idem"
   149 
   150 val predicator_name = "hBOOL"
   151 val app_op_name = "hAPP"
   152 val type_tag_name = "ti"
   153 val type_pred_name = "is"
   154 val simple_type_prefix = "ty_"
   155 
   156 val prefixed_predicator_name = const_prefix ^ predicator_name
   157 val prefixed_app_op_name = const_prefix ^ app_op_name
   158 val prefixed_type_tag_name = const_prefix ^ type_tag_name
   159 
   160 (* Freshness almost guaranteed! *)
   161 val atp_weak_prefix = "ATP:"
   162 
   163 (*Escaping of special characters.
   164   Alphanumeric characters are left unchanged.
   165   The character _ goes to __
   166   Characters in the range ASCII space to / go to _A to _P, respectively.
   167   Other characters go to _nnn where nnn is the decimal ASCII code.*)
   168 val upper_a_minus_space = Char.ord #"A" - Char.ord #" "
   169 
   170 fun stringN_of_int 0 _ = ""
   171   | stringN_of_int k n =
   172     stringN_of_int (k - 1) (n div 10) ^ string_of_int (n mod 10)
   173 
   174 fun ascii_of_char c =
   175   if Char.isAlphaNum c then
   176     String.str c
   177   else if c = #"_" then
   178     "__"
   179   else if #" " <= c andalso c <= #"/" then
   180     "_" ^ String.str (Char.chr (Char.ord c + upper_a_minus_space))
   181   else
   182     (* fixed width, in case more digits follow *)
   183     "_" ^ stringN_of_int 3 (Char.ord c)
   184 
   185 val ascii_of = String.translate ascii_of_char
   186 
   187 (** Remove ASCII armoring from names in proof files **)
   188 
   189 (* We don't raise error exceptions because this code can run inside a worker
   190    thread. Also, the errors are impossible. *)
   191 val unascii_of =
   192   let
   193     fun un rcs [] = String.implode(rev rcs)
   194       | un rcs [#"_"] = un (#"_" :: rcs) [] (* ERROR *)
   195         (* Three types of _ escapes: __, _A to _P, _nnn *)
   196       | un rcs (#"_" :: #"_" :: cs) = un (#"_" :: rcs) cs
   197       | un rcs (#"_" :: c :: cs) =
   198         if #"A" <= c andalso c<= #"P" then
   199           (* translation of #" " to #"/" *)
   200           un (Char.chr (Char.ord c - upper_a_minus_space) :: rcs) cs
   201         else
   202           let val digits = List.take (c :: cs, 3) handle General.Subscript => [] in
   203             case Int.fromString (String.implode digits) of
   204               SOME n => un (Char.chr n :: rcs) (List.drop (cs, 2))
   205             | NONE => un (c :: #"_" :: rcs) cs (* ERROR *)
   206           end
   207       | un rcs (c :: cs) = un (c :: rcs) cs
   208   in un [] o String.explode end
   209 
   210 (* If string s has the prefix s1, return the result of deleting it,
   211    un-ASCII'd. *)
   212 fun strip_prefix_and_unascii s1 s =
   213   if String.isPrefix s1 s then
   214     SOME (unascii_of (String.extract (s, size s1, NONE)))
   215   else
   216     NONE
   217 
   218 val proxy_table =
   219   [("c_False", (@{const_name False}, (@{thm fFalse_def},
   220        ("fFalse", @{const_name ATP.fFalse})))),
   221    ("c_True", (@{const_name True}, (@{thm fTrue_def},
   222        ("fTrue", @{const_name ATP.fTrue})))),
   223    ("c_Not", (@{const_name Not}, (@{thm fNot_def},
   224        ("fNot", @{const_name ATP.fNot})))),
   225    ("c_conj", (@{const_name conj}, (@{thm fconj_def},
   226        ("fconj", @{const_name ATP.fconj})))),
   227    ("c_disj", (@{const_name disj}, (@{thm fdisj_def},
   228        ("fdisj", @{const_name ATP.fdisj})))),
   229    ("c_implies", (@{const_name implies}, (@{thm fimplies_def},
   230        ("fimplies", @{const_name ATP.fimplies})))),
   231    ("equal", (@{const_name HOL.eq}, (@{thm fequal_def},
   232        ("fequal", @{const_name ATP.fequal})))),
   233    ("c_All", (@{const_name All}, (@{thm fAll_def},
   234        ("fAll", @{const_name ATP.fAll})))),
   235    ("c_Ex", (@{const_name Ex}, (@{thm fEx_def},
   236        ("fEx", @{const_name ATP.fEx}))))]
   237 
   238 val proxify_const = AList.lookup (op =) proxy_table #> Option.map (snd o snd)
   239 
   240 (* Readable names for the more common symbolic functions. Do not mess with the
   241    table unless you know what you are doing. *)
   242 val const_trans_table =
   243   [(@{type_name Product_Type.prod}, "prod"),
   244    (@{type_name Sum_Type.sum}, "sum"),
   245    (@{const_name False}, "False"),
   246    (@{const_name True}, "True"),
   247    (@{const_name Not}, "Not"),
   248    (@{const_name conj}, "conj"),
   249    (@{const_name disj}, "disj"),
   250    (@{const_name implies}, "implies"),
   251    (@{const_name HOL.eq}, "equal"),
   252    (@{const_name All}, "All"),
   253    (@{const_name Ex}, "Ex"),
   254    (@{const_name If}, "If"),
   255    (@{const_name Set.member}, "member"),
   256    (@{const_name Meson.COMBI}, "COMBI"),
   257    (@{const_name Meson.COMBK}, "COMBK"),
   258    (@{const_name Meson.COMBB}, "COMBB"),
   259    (@{const_name Meson.COMBC}, "COMBC"),
   260    (@{const_name Meson.COMBS}, "COMBS")]
   261   |> Symtab.make
   262   |> fold (Symtab.update o swap o snd o snd o snd) proxy_table
   263 
   264 (* Invert the table of translations between Isabelle and ATPs. *)
   265 val const_trans_table_inv =
   266   const_trans_table |> Symtab.dest |> map swap |> Symtab.make
   267 val const_trans_table_unprox =
   268   Symtab.empty
   269   |> fold (fn (_, (isa, (_, (_, atp)))) => Symtab.update (atp, isa)) proxy_table
   270 
   271 val invert_const = perhaps (Symtab.lookup const_trans_table_inv)
   272 val unproxify_const = perhaps (Symtab.lookup const_trans_table_unprox)
   273 
   274 fun lookup_const c =
   275   case Symtab.lookup const_trans_table c of
   276     SOME c' => c'
   277   | NONE => ascii_of c
   278 
   279 fun ascii_of_indexname (v, 0) = ascii_of v
   280   | ascii_of_indexname (v, i) = ascii_of v ^ "_" ^ string_of_int i
   281 
   282 fun make_bound_var x = bound_var_prefix ^ ascii_of x
   283 fun make_schematic_var v = schematic_var_prefix ^ ascii_of_indexname v
   284 fun make_fixed_var x = fixed_var_prefix ^ ascii_of x
   285 
   286 fun make_schematic_type_var (x, i) =
   287       tvar_prefix ^ (ascii_of_indexname (unprefix "'" x, i))
   288 fun make_fixed_type_var x = tfree_prefix ^ (ascii_of (unprefix "'" x))
   289 
   290 (* "HOL.eq" is mapped to the ATP's equality. *)
   291 fun make_fixed_const @{const_name HOL.eq} = tptp_old_equal
   292   | make_fixed_const c = const_prefix ^ lookup_const c
   293 
   294 fun make_fixed_type_const c = type_const_prefix ^ lookup_const c
   295 
   296 fun make_type_class clas = class_prefix ^ ascii_of clas
   297 
   298 fun new_skolem_var_name_from_const s =
   299   let val ss = s |> space_explode Long_Name.separator in
   300     nth ss (length ss - 2)
   301   end
   302 
   303 (* These are either simplified away by "Meson.presimplify" (most of the time) or
   304    handled specially via "fFalse", "fTrue", ..., "fequal". *)
   305 val atp_irrelevant_consts =
   306   [@{const_name False}, @{const_name True}, @{const_name Not},
   307    @{const_name conj}, @{const_name disj}, @{const_name implies},
   308    @{const_name HOL.eq}, @{const_name If}, @{const_name Let}]
   309 
   310 val atp_monomorph_bad_consts =
   311   atp_irrelevant_consts @
   312   (* These are ignored anyway by the relevance filter (unless they appear in
   313      higher-order places) but not by the monomorphizer. *)
   314   [@{const_name all}, @{const_name "==>"}, @{const_name "=="},
   315    @{const_name Trueprop}, @{const_name All}, @{const_name Ex},
   316    @{const_name Ex1}, @{const_name Ball}, @{const_name Bex}]
   317 
   318 fun add_schematic_const (x as (_, T)) =
   319   Monomorph.typ_has_tvars T ? Symtab.insert_list (op =) x
   320 val add_schematic_consts_of =
   321   Term.fold_aterms (fn Const (x as (s, _)) =>
   322                        not (member (op =) atp_monomorph_bad_consts s)
   323                        ? add_schematic_const x
   324                       | _ => I)
   325 fun atp_schematic_consts_of t = add_schematic_consts_of t Symtab.empty
   326 
   327 (** Definitions and functions for FOL clauses and formulas for TPTP **)
   328 
   329 (* The first component is the type class; the second is a "TVar" or "TFree". *)
   330 datatype type_literal =
   331   TyLitVar of name * name |
   332   TyLitFree of name * name
   333 
   334 
   335 (** Isabelle arities **)
   336 
   337 datatype arity_literal =
   338   TConsLit of name * name * name list |
   339   TVarLit of name * name
   340 
   341 fun gen_TVars 0 = []
   342   | gen_TVars n = ("T_" ^ string_of_int n) :: gen_TVars (n-1)
   343 
   344 val type_class = the_single @{sort type}
   345 
   346 fun add_packed_sort tvar =
   347   fold (fn s => s <> type_class ? cons (`make_type_class s, `I tvar))
   348 
   349 type arity_clause =
   350   {name : string,
   351    prem_lits : arity_literal list,
   352    concl_lits : arity_literal}
   353 
   354 (* Arity of type constructor "tcon :: (arg1, ..., argN) res" *)
   355 fun make_axiom_arity_clause (tcons, name, (cls, args)) =
   356   let
   357     val tvars = gen_TVars (length args)
   358     val tvars_srts = ListPair.zip (tvars, args)
   359   in
   360     {name = name,
   361      prem_lits = [] |> fold (uncurry add_packed_sort) tvars_srts |> map TVarLit,
   362      concl_lits = TConsLit (`make_type_class cls,
   363                             `make_fixed_type_const tcons,
   364                             tvars ~~ tvars)}
   365   end
   366 
   367 fun arity_clause _ _ (_, []) = []
   368   | arity_clause seen n (tcons, ("HOL.type", _) :: ars) =  (* ignore *)
   369     arity_clause seen n (tcons, ars)
   370   | arity_clause seen n (tcons, (ar as (class, _)) :: ars) =
   371     if member (op =) seen class then
   372       (* multiple arities for the same (tycon, class) pair *)
   373       make_axiom_arity_clause (tcons,
   374           lookup_const tcons ^ "___" ^ ascii_of class ^ "_" ^ string_of_int n,
   375           ar) ::
   376       arity_clause seen (n + 1) (tcons, ars)
   377     else
   378       make_axiom_arity_clause (tcons, lookup_const tcons ^ "___" ^
   379                                ascii_of class, ar) ::
   380       arity_clause (class :: seen) n (tcons, ars)
   381 
   382 fun multi_arity_clause [] = []
   383   | multi_arity_clause ((tcons, ars) :: tc_arlists) =
   384       arity_clause [] 1 (tcons, ars) @ multi_arity_clause tc_arlists
   385 
   386 (* Generate all pairs (tycon, class, sorts) such that tycon belongs to class in
   387    theory thy provided its arguments have the corresponding sorts. *)
   388 fun type_class_pairs thy tycons classes =
   389   let
   390     val alg = Sign.classes_of thy
   391     fun domain_sorts tycon = Sorts.mg_domain alg tycon o single
   392     fun add_class tycon class =
   393       cons (class, domain_sorts tycon class)
   394       handle Sorts.CLASS_ERROR _ => I
   395     fun try_classes tycon = (tycon, fold (add_class tycon) classes [])
   396   in map try_classes tycons end
   397 
   398 (*Proving one (tycon, class) membership may require proving others, so iterate.*)
   399 fun iter_type_class_pairs _ _ [] = ([], [])
   400   | iter_type_class_pairs thy tycons classes =
   401       let
   402         fun maybe_insert_class s =
   403           (s <> type_class andalso not (member (op =) classes s))
   404           ? insert (op =) s
   405         val cpairs = type_class_pairs thy tycons classes
   406         val newclasses =
   407           [] |> fold (fold (fold (fold maybe_insert_class) o snd) o snd) cpairs
   408         val (classes', cpairs') = iter_type_class_pairs thy tycons newclasses
   409       in (classes' @ classes, union (op =) cpairs' cpairs) end
   410 
   411 fun make_arity_clauses thy tycons =
   412   iter_type_class_pairs thy tycons ##> multi_arity_clause
   413 
   414 
   415 (** Isabelle class relations **)
   416 
   417 type class_rel_clause =
   418   {name : string,
   419    subclass : name,
   420    superclass : name}
   421 
   422 (* Generate all pairs (sub, super) such that sub is a proper subclass of super
   423    in theory "thy". *)
   424 fun class_pairs _ [] _ = []
   425   | class_pairs thy subs supers =
   426       let
   427         val class_less = Sorts.class_less (Sign.classes_of thy)
   428         fun add_super sub super = class_less (sub, super) ? cons (sub, super)
   429         fun add_supers sub = fold (add_super sub) supers
   430       in fold add_supers subs [] end
   431 
   432 fun make_class_rel_clause (sub, super) =
   433   {name = sub ^ "_" ^ super, subclass = `make_type_class sub,
   434    superclass = `make_type_class super}
   435 
   436 fun make_class_rel_clauses thy subs supers =
   437   map make_class_rel_clause (class_pairs thy subs supers)
   438 
   439 (* intermediate terms *)
   440 datatype iterm =
   441   IConst of name * typ * typ list |
   442   IVar of name * typ |
   443   IApp of iterm * iterm |
   444   IAbs of (name * typ) * iterm
   445 
   446 fun ityp_of (IConst (_, T, _)) = T
   447   | ityp_of (IVar (_, T)) = T
   448   | ityp_of (IApp (t1, _)) = snd (dest_funT (ityp_of t1))
   449   | ityp_of (IAbs ((_, T), tm)) = T --> ityp_of tm
   450 
   451 (*gets the head of a combinator application, along with the list of arguments*)
   452 fun strip_iterm_comb u =
   453   let
   454     fun stripc (IApp (t, u), ts) = stripc (t, u :: ts)
   455       | stripc x = x
   456   in stripc (u, []) end
   457 
   458 fun atyps_of T = fold_atyps (insert (op =)) T []
   459 
   460 fun new_skolem_const_name s num_T_args =
   461   [new_skolem_const_prefix, s, string_of_int num_T_args]
   462   |> space_implode Long_Name.separator
   463 
   464 (* Converts an Isabelle/HOL term (with combinators) into an intermediate term.
   465    Also accumulates sort infomation. *)
   466 fun iterm_from_term thy bs (P $ Q) =
   467     let
   468       val (P', P_atomics_Ts) = iterm_from_term thy bs P
   469       val (Q', Q_atomics_Ts) = iterm_from_term thy bs Q
   470     in (IApp (P', Q'), union (op =) P_atomics_Ts Q_atomics_Ts) end
   471   | iterm_from_term thy _ (Const (c, T)) =
   472     (IConst (`make_fixed_const c, T,
   473              if String.isPrefix old_skolem_const_prefix c then
   474                [] |> Term.add_tvarsT T |> map TVar
   475              else
   476                (c, T) |> Sign.const_typargs thy),
   477      atyps_of T)
   478   | iterm_from_term _ _ (Free (s, T)) =
   479     (IConst (`make_fixed_var s, T,
   480              if String.isPrefix polymorphic_free_prefix s then [T] else []),
   481      atyps_of T)
   482   | iterm_from_term _ _ (Var (v as (s, _), T)) =
   483     (if String.isPrefix Meson_Clausify.new_skolem_var_prefix s then
   484        let
   485          val Ts = T |> strip_type |> swap |> op ::
   486          val s' = new_skolem_const_name s (length Ts)
   487        in IConst (`make_fixed_const s', T, Ts) end
   488      else
   489        IVar ((make_schematic_var v, s), T), atyps_of T)
   490   | iterm_from_term _ bs (Bound j) =
   491     nth bs j |> (fn (s, T) => (IConst (`make_bound_var s, T, []), atyps_of T))
   492   | iterm_from_term thy bs (Abs (s, T, t)) =
   493     let
   494       fun vary s = s |> AList.defined (op =) bs s ? vary o Symbol.bump_string
   495       val s = vary s
   496       val (tm, atomic_Ts) = iterm_from_term thy ((s, T) :: bs) t
   497     in
   498       (IAbs ((`make_bound_var s, T), tm),
   499        union (op =) atomic_Ts (atyps_of T))
   500     end
   501 
   502 datatype locality =
   503   General | Helper | Extensionality | Intro | Elim | Simp | Local | Assum |
   504   Chained
   505 
   506 (* (quasi-)underapproximation of the truth *)
   507 fun is_locality_global Local = false
   508   | is_locality_global Assum = false
   509   | is_locality_global Chained = false
   510   | is_locality_global _ = true
   511 
   512 datatype order = First_Order | Higher_Order
   513 datatype polymorphism = Polymorphic | Monomorphic | Mangled_Monomorphic
   514 datatype type_level =
   515   All_Types | Noninf_Nonmono_Types | Fin_Nonmono_Types | Const_Arg_Types |
   516   No_Types
   517 datatype type_heaviness = Heavyweight | Lightweight
   518 
   519 datatype type_enc =
   520   Simple_Types of order * type_level |
   521   Preds of polymorphism * type_level * type_heaviness |
   522   Tags of polymorphism * type_level * type_heaviness
   523 
   524 fun try_unsuffixes ss s =
   525   fold (fn s' => fn NONE => try (unsuffix s') s | some => some) ss NONE
   526 
   527 fun type_enc_from_string s =
   528   (case try (unprefix "poly_") s of
   529      SOME s => (SOME Polymorphic, s)
   530    | NONE =>
   531      case try (unprefix "mono_") s of
   532        SOME s => (SOME Monomorphic, s)
   533      | NONE =>
   534        case try (unprefix "mangled_") s of
   535          SOME s => (SOME Mangled_Monomorphic, s)
   536        | NONE => (NONE, s))
   537   ||> (fn s =>
   538           (* "_query" and "_bang" are for the ASCII-challenged Metis and
   539              Mirabelle. *)
   540           case try_unsuffixes ["?", "_query"] s of
   541             SOME s => (Noninf_Nonmono_Types, s)
   542           | NONE =>
   543             case try_unsuffixes ["!", "_bang"] s of
   544               SOME s => (Fin_Nonmono_Types, s)
   545             | NONE => (All_Types, s))
   546   ||> apsnd (fn s =>
   547                 case try (unsuffix "_heavy") s of
   548                   SOME s => (Heavyweight, s)
   549                 | NONE => (Lightweight, s))
   550   |> (fn (poly, (level, (heaviness, core))) =>
   551          case (core, (poly, level, heaviness)) of
   552            ("simple", (NONE, _, Lightweight)) =>
   553            Simple_Types (First_Order, level)
   554          | ("simple_higher", (NONE, _, Lightweight)) =>
   555            if level = Noninf_Nonmono_Types then raise Same.SAME
   556            else Simple_Types (Higher_Order, level)
   557          | ("preds", (SOME poly, _, _)) => Preds (poly, level, heaviness)
   558          | ("tags", (SOME Polymorphic, _, _)) =>
   559            Tags (Polymorphic, level, heaviness)
   560          | ("tags", (SOME poly, _, _)) => Tags (poly, level, heaviness)
   561          | ("args", (SOME poly, All_Types (* naja *), Lightweight)) =>
   562            Preds (poly, Const_Arg_Types, Lightweight)
   563          | ("erased", (NONE, All_Types (* naja *), Lightweight)) =>
   564            Preds (Polymorphic, No_Types, Lightweight)
   565          | _ => raise Same.SAME)
   566   handle Same.SAME => error ("Unknown type system: " ^ quote s ^ ".")
   567 
   568 fun is_type_enc_higher_order (Simple_Types (Higher_Order, _)) = true
   569   | is_type_enc_higher_order _ = false
   570 
   571 fun polymorphism_of_type_enc (Simple_Types _) = Mangled_Monomorphic
   572   | polymorphism_of_type_enc (Preds (poly, _, _)) = poly
   573   | polymorphism_of_type_enc (Tags (poly, _, _)) = poly
   574 
   575 fun level_of_type_enc (Simple_Types (_, level)) = level
   576   | level_of_type_enc (Preds (_, level, _)) = level
   577   | level_of_type_enc (Tags (_, level, _)) = level
   578 
   579 fun heaviness_of_type_enc (Simple_Types _) = Heavyweight
   580   | heaviness_of_type_enc (Preds (_, _, heaviness)) = heaviness
   581   | heaviness_of_type_enc (Tags (_, _, heaviness)) = heaviness
   582 
   583 fun is_type_level_virtually_sound level =
   584   level = All_Types orelse level = Noninf_Nonmono_Types
   585 val is_type_enc_virtually_sound =
   586   is_type_level_virtually_sound o level_of_type_enc
   587 
   588 fun is_type_level_fairly_sound level =
   589   is_type_level_virtually_sound level orelse level = Fin_Nonmono_Types
   590 val is_type_enc_fairly_sound = is_type_level_fairly_sound o level_of_type_enc
   591 
   592 fun choose_format formats (Simple_Types (order, level)) =
   593     if member (op =) formats THF then
   594       (THF, Simple_Types (order, level))
   595     else if member (op =) formats TFF then
   596       (TFF, Simple_Types (First_Order, level))
   597     else
   598       choose_format formats (Preds (Mangled_Monomorphic, level, Heavyweight))
   599   | choose_format formats type_enc =
   600     (case hd formats of
   601        CNF_UEQ =>
   602        (CNF_UEQ, case type_enc of
   603                    Preds stuff =>
   604                    (if is_type_enc_fairly_sound type_enc then Tags else Preds)
   605                        stuff
   606                  | _ => type_enc)
   607      | format => (format, type_enc))
   608 
   609 type translated_formula =
   610   {name : string,
   611    locality : locality,
   612    kind : formula_kind,
   613    iformula : (name, typ, iterm) formula,
   614    atomic_types : typ list}
   615 
   616 fun update_iformula f ({name, locality, kind, iformula, atomic_types}
   617                        : translated_formula) =
   618   {name = name, locality = locality, kind = kind, iformula = f iformula,
   619    atomic_types = atomic_types} : translated_formula
   620 
   621 fun fact_lift f ({iformula, ...} : translated_formula) = f iformula
   622 
   623 val type_instance = Sign.typ_instance o Proof_Context.theory_of
   624 
   625 fun insert_type ctxt get_T x xs =
   626   let val T = get_T x in
   627     if exists (curry (type_instance ctxt) T o get_T) xs then xs
   628     else x :: filter_out (curry (type_instance ctxt o swap) T o get_T) xs
   629   end
   630 
   631 (* The Booleans indicate whether all type arguments should be kept. *)
   632 datatype type_arg_policy =
   633   Explicit_Type_Args of bool |
   634   Mangled_Type_Args of bool |
   635   No_Type_Args
   636 
   637 fun should_drop_arg_type_args (Simple_Types _) =
   638     false (* since TFF doesn't support overloading *)
   639   | should_drop_arg_type_args type_enc =
   640     level_of_type_enc type_enc = All_Types andalso
   641     heaviness_of_type_enc type_enc = Heavyweight
   642 
   643 fun type_arg_policy type_enc s =
   644   if s = type_tag_name then
   645     (if polymorphism_of_type_enc type_enc = Mangled_Monomorphic then
   646        Mangled_Type_Args
   647      else
   648        Explicit_Type_Args) false
   649   else case type_enc of
   650     Tags (_, All_Types, Heavyweight) => No_Type_Args
   651   | _ =>
   652     if level_of_type_enc type_enc = No_Types orelse
   653        s = @{const_name HOL.eq} orelse
   654        (s = app_op_name andalso
   655         level_of_type_enc type_enc = Const_Arg_Types) then
   656       No_Type_Args
   657     else
   658       should_drop_arg_type_args type_enc
   659       |> (if polymorphism_of_type_enc type_enc = Mangled_Monomorphic then
   660             Mangled_Type_Args
   661           else
   662             Explicit_Type_Args)
   663 
   664 (* Make literals for sorted type variables. *)
   665 fun generic_add_sorts_on_type (_, []) = I
   666   | generic_add_sorts_on_type ((x, i), s :: ss) =
   667     generic_add_sorts_on_type ((x, i), ss)
   668     #> (if s = the_single @{sort HOL.type} then
   669           I
   670         else if i = ~1 then
   671           insert (op =) (TyLitFree (`make_type_class s, `make_fixed_type_var x))
   672         else
   673           insert (op =) (TyLitVar (`make_type_class s,
   674                                    (make_schematic_type_var (x, i), x))))
   675 fun add_sorts_on_tfree (TFree (s, S)) = generic_add_sorts_on_type ((s, ~1), S)
   676   | add_sorts_on_tfree _ = I
   677 fun add_sorts_on_tvar (TVar z) = generic_add_sorts_on_type z
   678   | add_sorts_on_tvar _ = I
   679 
   680 fun type_literals_for_types type_enc add_sorts_on_typ Ts =
   681   [] |> level_of_type_enc type_enc <> No_Types ? fold add_sorts_on_typ Ts
   682 
   683 fun mk_aconns c phis =
   684   let val (phis', phi') = split_last phis in
   685     fold_rev (mk_aconn c) phis' phi'
   686   end
   687 fun mk_ahorn [] phi = phi
   688   | mk_ahorn phis psi = AConn (AImplies, [mk_aconns AAnd phis, psi])
   689 fun mk_aquant _ [] phi = phi
   690   | mk_aquant q xs (phi as AQuant (q', xs', phi')) =
   691     if q = q' then AQuant (q, xs @ xs', phi') else AQuant (q, xs, phi)
   692   | mk_aquant q xs phi = AQuant (q, xs, phi)
   693 
   694 fun close_universally atom_vars phi =
   695   let
   696     fun formula_vars bounds (AQuant (_, xs, phi)) =
   697         formula_vars (map fst xs @ bounds) phi
   698       | formula_vars bounds (AConn (_, phis)) = fold (formula_vars bounds) phis
   699       | formula_vars bounds (AAtom tm) =
   700         union (op =) (atom_vars tm []
   701                       |> filter_out (member (op =) bounds o fst))
   702   in mk_aquant AForall (formula_vars [] phi []) phi end
   703 
   704 fun iterm_vars (IApp (tm1, tm2)) = fold iterm_vars [tm1, tm2]
   705   | iterm_vars (IConst _) = I
   706   | iterm_vars (IVar (name, T)) = insert (op =) (name, SOME T)
   707   | iterm_vars (IAbs (_, tm)) = iterm_vars tm
   708 fun close_iformula_universally phi = close_universally iterm_vars phi
   709 
   710 fun term_vars bounds (ATerm (name as (s, _), tms)) =
   711     (is_tptp_variable s andalso not (member (op =) bounds name))
   712     ? insert (op =) (name, NONE) #> fold (term_vars bounds) tms
   713   | term_vars bounds (AAbs ((name, _), tm)) = term_vars (name :: bounds) tm
   714 fun close_formula_universally phi = close_universally (term_vars []) phi
   715 
   716 val homo_infinite_type_name = @{type_name ind} (* any infinite type *)
   717 val homo_infinite_type = Type (homo_infinite_type_name, [])
   718 
   719 fun ho_term_from_typ format type_enc =
   720   let
   721     fun term (Type (s, Ts)) =
   722       ATerm (case (is_type_enc_higher_order type_enc, s) of
   723                (true, @{type_name bool}) => `I tptp_bool_type
   724              | (true, @{type_name fun}) => `I tptp_fun_type
   725              | _ => if s = homo_infinite_type_name andalso
   726                        (format = TFF orelse format = THF) then
   727                       `I tptp_individual_type
   728                     else
   729                       `make_fixed_type_const s,
   730              map term Ts)
   731     | term (TFree (s, _)) = ATerm (`make_fixed_type_var s, [])
   732     | term (TVar ((x as (s, _)), _)) =
   733       ATerm ((make_schematic_type_var x, s), [])
   734   in term end
   735 
   736 fun ho_term_for_type_arg format type_enc T =
   737   if T = dummyT then NONE else SOME (ho_term_from_typ format type_enc T)
   738 
   739 (* This shouldn't clash with anything else. *)
   740 val mangled_type_sep = "\000"
   741 
   742 fun generic_mangled_type_name f (ATerm (name, [])) = f name
   743   | generic_mangled_type_name f (ATerm (name, tys)) =
   744     f name ^ "(" ^ space_implode "," (map (generic_mangled_type_name f) tys)
   745     ^ ")"
   746   | generic_mangled_type_name _ _ = raise Fail "unexpected type abstraction"
   747 
   748 val bool_atype = AType (`I tptp_bool_type)
   749 
   750 fun make_simple_type s =
   751   if s = tptp_bool_type orelse s = tptp_fun_type orelse
   752      s = tptp_individual_type then
   753     s
   754   else
   755     simple_type_prefix ^ ascii_of s
   756 
   757 fun ho_type_from_ho_term type_enc pred_sym ary =
   758   let
   759     fun to_atype ty =
   760       AType ((make_simple_type (generic_mangled_type_name fst ty),
   761               generic_mangled_type_name snd ty))
   762     fun to_afun f1 f2 tys = AFun (f1 (hd tys), f2 (nth tys 1))
   763     fun to_fo 0 ty = if pred_sym then bool_atype else to_atype ty
   764       | to_fo ary (ATerm (_, tys)) = to_afun to_atype (to_fo (ary - 1)) tys
   765       | to_fo _ _ = raise Fail "unexpected type abstraction"
   766     fun to_ho (ty as ATerm ((s, _), tys)) =
   767         if s = tptp_fun_type then to_afun to_ho to_ho tys else to_atype ty
   768       | to_ho _ = raise Fail "unexpected type abstraction"
   769   in if is_type_enc_higher_order type_enc then to_ho else to_fo ary end
   770 
   771 fun ho_type_from_typ format type_enc pred_sym ary =
   772   ho_type_from_ho_term type_enc pred_sym ary
   773   o ho_term_from_typ format type_enc
   774 
   775 fun mangled_const_name format type_enc T_args (s, s') =
   776   let
   777     val ty_args = T_args |> map_filter (ho_term_for_type_arg format type_enc)
   778     fun type_suffix f g =
   779       fold_rev (curry (op ^) o g o prefix mangled_type_sep
   780                 o generic_mangled_type_name f) ty_args ""
   781   in (s ^ type_suffix fst ascii_of, s' ^ type_suffix snd I) end
   782 
   783 val parse_mangled_ident =
   784   Scan.many1 (not o member (op =) ["(", ")", ","]) >> implode
   785 
   786 fun parse_mangled_type x =
   787   (parse_mangled_ident
   788    -- Scan.optional ($$ "(" |-- Scan.optional parse_mangled_types [] --| $$ ")")
   789                     [] >> ATerm) x
   790 and parse_mangled_types x =
   791   (parse_mangled_type ::: Scan.repeat ($$ "," |-- parse_mangled_type)) x
   792 
   793 fun unmangled_type s =
   794   s |> suffix ")" |> raw_explode
   795     |> Scan.finite Symbol.stopper
   796            (Scan.error (!! (fn _ => raise Fail ("unrecognized mangled type " ^
   797                                                 quote s)) parse_mangled_type))
   798     |> fst
   799 
   800 val unmangled_const_name = space_explode mangled_type_sep #> hd
   801 fun unmangled_const s =
   802   let val ss = space_explode mangled_type_sep s in
   803     (hd ss, map unmangled_type (tl ss))
   804   end
   805 
   806 fun introduce_proxies type_enc =
   807   let
   808     fun intro top_level (IApp (tm1, tm2)) =
   809         IApp (intro top_level tm1, intro false tm2)
   810       | intro top_level (IConst (name as (s, _), T, T_args)) =
   811         (case proxify_const s of
   812            SOME proxy_base =>
   813            if top_level orelse is_type_enc_higher_order type_enc then
   814              case (top_level, s) of
   815                (_, "c_False") => (`I tptp_false, [])
   816              | (_, "c_True") => (`I tptp_true, [])
   817              | (false, "c_Not") => (`I tptp_not, [])
   818              | (false, "c_conj") => (`I tptp_and, [])
   819              | (false, "c_disj") => (`I tptp_or, [])
   820              | (false, "c_implies") => (`I tptp_implies, [])
   821              | (false, "c_All") => (`I tptp_ho_forall, [])
   822              | (false, "c_Ex") => (`I tptp_ho_exists, [])
   823              | (false, s) =>
   824                if is_tptp_equal s then (`I tptp_equal, [])
   825                else (proxy_base |>> prefix const_prefix, T_args)
   826              | _ => (name, [])
   827            else
   828              (proxy_base |>> prefix const_prefix, T_args)
   829           | NONE => (name, T_args))
   830         |> (fn (name, T_args) => IConst (name, T, T_args))
   831       | intro _ (IAbs (bound, tm)) = IAbs (bound, intro false tm)
   832       | intro _ tm = tm
   833   in intro true end
   834 
   835 fun iformula_from_prop thy type_enc eq_as_iff =
   836   let
   837     fun do_term bs t atomic_types =
   838       iterm_from_term thy bs (Envir.eta_contract t)
   839       |>> (introduce_proxies type_enc #> AAtom)
   840       ||> union (op =) atomic_types
   841     fun do_quant bs q s T t' =
   842       let val s = singleton (Name.variant_list (map fst bs)) s in
   843         do_formula ((s, T) :: bs) t'
   844         #>> mk_aquant q [(`make_bound_var s, SOME T)]
   845       end
   846     and do_conn bs c t1 t2 =
   847       do_formula bs t1 ##>> do_formula bs t2 #>> uncurry (mk_aconn c)
   848     and do_formula bs t =
   849       case t of
   850         @{const Trueprop} $ t1 => do_formula bs t1
   851       | @{const Not} $ t1 => do_formula bs t1 #>> mk_anot
   852       | Const (@{const_name All}, _) $ Abs (s, T, t') =>
   853         do_quant bs AForall s T t'
   854       | Const (@{const_name Ex}, _) $ Abs (s, T, t') =>
   855         do_quant bs AExists s T t'
   856       | @{const HOL.conj} $ t1 $ t2 => do_conn bs AAnd t1 t2
   857       | @{const HOL.disj} $ t1 $ t2 => do_conn bs AOr t1 t2
   858       | @{const HOL.implies} $ t1 $ t2 => do_conn bs AImplies t1 t2
   859       | Const (@{const_name HOL.eq}, Type (_, [@{typ bool}, _])) $ t1 $ t2 =>
   860         if eq_as_iff then do_conn bs AIff t1 t2 else do_term bs t
   861       | _ => do_term bs t
   862   in do_formula [] end
   863 
   864 fun presimplify_term _ [] t = t
   865   | presimplify_term ctxt presimp_consts t =
   866     t |> exists_Const (member (op =) presimp_consts o fst) t
   867          ? (Skip_Proof.make_thm (Proof_Context.theory_of ctxt)
   868             #> Meson.presimplify ctxt
   869             #> prop_of)
   870 
   871 fun concealed_bound_name j = atp_weak_prefix ^ string_of_int j
   872 fun conceal_bounds Ts t =
   873   subst_bounds (map (Free o apfst concealed_bound_name)
   874                     (0 upto length Ts - 1 ~~ Ts), t)
   875 fun reveal_bounds Ts =
   876   subst_atomic (map (fn (j, T) => (Free (concealed_bound_name j, T), Bound j))
   877                     (0 upto length Ts - 1 ~~ Ts))
   878 
   879 fun is_fun_equality (@{const_name HOL.eq},
   880                      Type (_, [Type (@{type_name fun}, _), _])) = true
   881   | is_fun_equality _ = false
   882 
   883 fun extensionalize_term ctxt t =
   884   if exists_Const is_fun_equality t then
   885     let val thy = Proof_Context.theory_of ctxt in
   886       t |> cterm_of thy |> Meson.extensionalize_conv ctxt
   887         |> prop_of |> Logic.dest_equals |> snd
   888     end
   889   else
   890     t
   891 
   892 fun simple_translate_lambdas do_lambdas ctxt t =
   893   let val thy = Proof_Context.theory_of ctxt in
   894     if Meson.is_fol_term thy t then
   895       t
   896     else
   897       let
   898         fun aux Ts t =
   899           case t of
   900             @{const Not} $ t1 => @{const Not} $ aux Ts t1
   901           | (t0 as Const (@{const_name All}, _)) $ Abs (s, T, t') =>
   902             t0 $ Abs (s, T, aux (T :: Ts) t')
   903           | (t0 as Const (@{const_name All}, _)) $ t1 =>
   904             aux Ts (t0 $ eta_expand Ts t1 1)
   905           | (t0 as Const (@{const_name Ex}, _)) $ Abs (s, T, t') =>
   906             t0 $ Abs (s, T, aux (T :: Ts) t')
   907           | (t0 as Const (@{const_name Ex}, _)) $ t1 =>
   908             aux Ts (t0 $ eta_expand Ts t1 1)
   909           | (t0 as @{const HOL.conj}) $ t1 $ t2 => t0 $ aux Ts t1 $ aux Ts t2
   910           | (t0 as @{const HOL.disj}) $ t1 $ t2 => t0 $ aux Ts t1 $ aux Ts t2
   911           | (t0 as @{const HOL.implies}) $ t1 $ t2 => t0 $ aux Ts t1 $ aux Ts t2
   912           | (t0 as Const (@{const_name HOL.eq}, Type (_, [@{typ bool}, _])))
   913               $ t1 $ t2 =>
   914             t0 $ aux Ts t1 $ aux Ts t2
   915           | _ =>
   916             if not (exists_subterm (fn Abs _ => true | _ => false) t) then t
   917             else t |> Envir.eta_contract |> do_lambdas ctxt Ts
   918         val (t, ctxt') = Variable.import_terms true [t] ctxt |>> the_single
   919       in t |> aux [] |> singleton (Variable.export_terms ctxt' ctxt) end
   920   end
   921 
   922 fun do_conceal_lambdas Ts (t1 $ t2) =
   923     do_conceal_lambdas Ts t1 $ do_conceal_lambdas Ts t2
   924   | do_conceal_lambdas Ts (Abs (_, T, t)) =
   925     (* slightly unsound because of hash collisions *)
   926     Free (polymorphic_free_prefix ^ serial_string (), T --> fastype_of1 (Ts, t))
   927   | do_conceal_lambdas _ t = t
   928 
   929 fun do_introduce_combinators ctxt Ts t =
   930   let val thy = Proof_Context.theory_of ctxt in
   931     t |> conceal_bounds Ts
   932       |> cterm_of thy
   933       |> Meson_Clausify.introduce_combinators_in_cterm
   934       |> prop_of |> Logic.dest_equals |> snd
   935       |> reveal_bounds Ts
   936   end
   937   (* A type variable of sort "{}" will make abstraction fail. *)
   938   handle THM _ => t |> do_conceal_lambdas Ts
   939 val introduce_combinators = simple_translate_lambdas do_introduce_combinators
   940 
   941 fun preprocess_abstractions_in_terms trans_lambdas facts =
   942   let
   943     val (facts, lambda_ts) =
   944       facts |> map (snd o snd) |> trans_lambdas 
   945             |>> map2 (fn (name, (kind, _)) => fn t => (name, (kind, t))) facts
   946     val lambda_facts =
   947       map2 (fn t => fn j =>
   948                ((lambda_fact_prefix ^ Int.toString j, Helper), (Axiom, t)))
   949            lambda_ts (1 upto length lambda_ts)
   950   in (facts, lambda_facts) end
   951 
   952 (* Metis's use of "resolve_tac" freezes the schematic variables. We simulate the
   953    same in Sledgehammer to prevent the discovery of unreplayable proofs. *)
   954 fun freeze_term t =
   955   let
   956     fun aux (t $ u) = aux t $ aux u
   957       | aux (Abs (s, T, t)) = Abs (s, T, aux t)
   958       | aux (Var ((s, i), T)) =
   959         Free (atp_weak_prefix ^ s ^ "_" ^ string_of_int i, T)
   960       | aux t = t
   961   in t |> exists_subterm is_Var t ? aux end
   962 
   963 fun presimp_prop ctxt presimp_consts t =
   964   let
   965     val thy = Proof_Context.theory_of ctxt
   966     val t = t |> Envir.beta_eta_contract
   967               |> transform_elim_prop
   968               |> Object_Logic.atomize_term thy
   969     val need_trueprop = (fastype_of t = @{typ bool})
   970   in
   971     t |> need_trueprop ? HOLogic.mk_Trueprop
   972       |> Raw_Simplifier.rewrite_term thy (Meson.unfold_set_const_simps ctxt) []
   973       |> extensionalize_term ctxt
   974       |> presimplify_term ctxt presimp_consts
   975       |> perhaps (try (HOLogic.dest_Trueprop))
   976   end
   977 
   978 (* making fact and conjecture formulas *)
   979 fun make_formula thy type_enc eq_as_iff name loc kind t =
   980   let
   981     val (iformula, atomic_types) =
   982       iformula_from_prop thy type_enc eq_as_iff t []
   983   in
   984     {name = name, locality = loc, kind = kind, iformula = iformula,
   985      atomic_types = atomic_types}
   986   end
   987 
   988 fun make_fact ctxt format type_enc eq_as_iff ((name, loc), t) =
   989   let val thy = Proof_Context.theory_of ctxt in
   990     case t |> make_formula thy type_enc (eq_as_iff andalso format <> CNF) name
   991                            loc Axiom of
   992       formula as {iformula = AAtom (IConst ((s, _), _, _)), ...} =>
   993       if s = tptp_true then NONE else SOME formula
   994     | formula => SOME formula
   995   end
   996 
   997 fun make_conjecture ctxt format type_enc ps =
   998   let
   999     val thy = Proof_Context.theory_of ctxt
  1000     val last = length ps - 1
  1001   in
  1002     map2 (fn j => fn ((name, loc), (kind, t)) =>
  1003              t |> make_formula thy type_enc (format <> CNF) name loc kind
  1004                |> (j <> last) = (kind = Conjecture) ? update_iformula mk_anot)
  1005          (0 upto last) ps
  1006   end
  1007 
  1008 (** Finite and infinite type inference **)
  1009 
  1010 fun deep_freeze_atyp (TVar (_, S)) = TFree ("v", S)
  1011   | deep_freeze_atyp T = T
  1012 val deep_freeze_type = map_atyps deep_freeze_atyp
  1013 
  1014 (* Finite types such as "unit", "bool", "bool * bool", and "bool => bool" are
  1015    dangerous because their "exhaust" properties can easily lead to unsound ATP
  1016    proofs. On the other hand, all HOL infinite types can be given the same
  1017    models in first-order logic (via Löwenheim-Skolem). *)
  1018 
  1019 fun should_encode_type ctxt (nonmono_Ts as _ :: _) _ T =
  1020     exists (curry (type_instance ctxt) (deep_freeze_type T)) nonmono_Ts
  1021   | should_encode_type _ _ All_Types _ = true
  1022   | should_encode_type ctxt _ Fin_Nonmono_Types T =
  1023     is_type_surely_finite ctxt false T
  1024   | should_encode_type _ _ _ _ = false
  1025 
  1026 fun should_predicate_on_type ctxt nonmono_Ts (Preds (_, level, heaviness))
  1027                              should_predicate_on_var T =
  1028     (heaviness = Heavyweight orelse should_predicate_on_var ()) andalso
  1029     should_encode_type ctxt nonmono_Ts level T
  1030   | should_predicate_on_type _ _ _ _ _ = false
  1031 
  1032 fun is_var_or_bound_var (IConst ((s, _), _, _)) =
  1033     String.isPrefix bound_var_prefix s
  1034   | is_var_or_bound_var (IVar _) = true
  1035   | is_var_or_bound_var _ = false
  1036 
  1037 datatype tag_site =
  1038   Top_Level of bool option |
  1039   Eq_Arg of bool option |
  1040   Elsewhere
  1041 
  1042 fun should_tag_with_type _ _ _ (Top_Level _) _ _ = false
  1043   | should_tag_with_type ctxt nonmono_Ts (Tags (poly, level, heaviness)) site
  1044                          u T =
  1045     (case heaviness of
  1046        Heavyweight => should_encode_type ctxt nonmono_Ts level T
  1047      | Lightweight =>
  1048        case (site, is_var_or_bound_var u) of
  1049          (Eq_Arg pos, true) =>
  1050          (* The first disjunct prevents a subtle soundness issue explained in
  1051             Blanchette's Ph.D. thesis. See also
  1052             "formula_lines_for_lightweight_tags_sym_decl". *)
  1053          (pos <> SOME false andalso poly = Polymorphic andalso
  1054           level <> All_Types andalso heaviness = Lightweight andalso
  1055           exists (fn T' => type_instance ctxt (T', T)) nonmono_Ts) orelse
  1056          should_encode_type ctxt nonmono_Ts level T
  1057        | _ => false)
  1058   | should_tag_with_type _ _ _ _ _ _ = false
  1059 
  1060 fun homogenized_type ctxt nonmono_Ts level =
  1061   let
  1062     val should_encode = should_encode_type ctxt nonmono_Ts level
  1063     fun homo 0 T = if should_encode T then T else homo_infinite_type
  1064       | homo ary (Type (@{type_name fun}, [T1, T2])) =
  1065         homo 0 T1 --> homo (ary - 1) T2
  1066       | homo _ _ = raise Fail "expected function type"
  1067   in homo end
  1068 
  1069 (** "hBOOL" and "hAPP" **)
  1070 
  1071 type sym_info =
  1072   {pred_sym : bool, min_ary : int, max_ary : int, types : typ list}
  1073 
  1074 fun add_iterm_syms_to_table ctxt explicit_apply =
  1075   let
  1076     fun consider_var_arity const_T var_T max_ary =
  1077       let
  1078         fun iter ary T =
  1079           if ary = max_ary orelse type_instance ctxt (var_T, T) orelse
  1080              type_instance ctxt (T, var_T) then
  1081             ary
  1082           else
  1083             iter (ary + 1) (range_type T)
  1084       in iter 0 const_T end
  1085     fun add_var_or_bound_var T (accum as ((bool_vars, fun_var_Ts), sym_tab)) =
  1086       if explicit_apply = NONE andalso
  1087          (can dest_funT T orelse T = @{typ bool}) then
  1088         let
  1089           val bool_vars' = bool_vars orelse body_type T = @{typ bool}
  1090           fun repair_min_arity {pred_sym, min_ary, max_ary, types} =
  1091             {pred_sym = pred_sym andalso not bool_vars',
  1092              min_ary = fold (fn T' => consider_var_arity T' T) types min_ary,
  1093              max_ary = max_ary, types = types}
  1094           val fun_var_Ts' =
  1095             fun_var_Ts |> can dest_funT T ? insert_type ctxt I T
  1096         in
  1097           if bool_vars' = bool_vars andalso
  1098              pointer_eq (fun_var_Ts', fun_var_Ts) then
  1099             accum
  1100           else
  1101             ((bool_vars', fun_var_Ts'), Symtab.map (K repair_min_arity) sym_tab)
  1102         end
  1103       else
  1104         accum
  1105     fun add top_level tm (accum as ((bool_vars, fun_var_Ts), sym_tab)) =
  1106       let val (head, args) = strip_iterm_comb tm in
  1107         (case head of
  1108            IConst ((s, _), T, _) =>
  1109            if String.isPrefix bound_var_prefix s then
  1110              add_var_or_bound_var T accum
  1111            else
  1112              let val ary = length args in
  1113                ((bool_vars, fun_var_Ts),
  1114                 case Symtab.lookup sym_tab s of
  1115                   SOME {pred_sym, min_ary, max_ary, types} =>
  1116                   let
  1117                     val pred_sym =
  1118                       pred_sym andalso top_level andalso not bool_vars
  1119                     val types' = types |> insert_type ctxt I T
  1120                     val min_ary =
  1121                       if is_some explicit_apply orelse
  1122                          pointer_eq (types', types) then
  1123                         min_ary
  1124                       else
  1125                         fold (consider_var_arity T) fun_var_Ts min_ary
  1126                   in
  1127                     Symtab.update (s, {pred_sym = pred_sym,
  1128                                        min_ary = Int.min (ary, min_ary),
  1129                                        max_ary = Int.max (ary, max_ary),
  1130                                        types = types'})
  1131                                   sym_tab
  1132                   end
  1133                 | NONE =>
  1134                   let
  1135                     val pred_sym = top_level andalso not bool_vars
  1136                     val min_ary =
  1137                       case explicit_apply of
  1138                         SOME true => 0
  1139                       | SOME false => ary
  1140                       | NONE => fold (consider_var_arity T) fun_var_Ts ary
  1141                   in
  1142                     Symtab.update_new (s, {pred_sym = pred_sym,
  1143                                            min_ary = min_ary, max_ary = ary,
  1144                                            types = [T]})
  1145                                       sym_tab
  1146                   end)
  1147              end
  1148          | IVar (_, T) => add_var_or_bound_var T accum
  1149          | IAbs ((_, T), tm) => accum |> add_var_or_bound_var T |> add false tm
  1150          | _ => accum)
  1151         |> fold (add false) args
  1152       end
  1153   in add true end
  1154 fun add_fact_syms_to_table ctxt explicit_apply =
  1155   fact_lift (formula_fold NONE
  1156                           (K (add_iterm_syms_to_table ctxt explicit_apply)))
  1157 
  1158 val default_sym_tab_entries : (string * sym_info) list =
  1159   (prefixed_predicator_name,
  1160    {pred_sym = true, min_ary = 1, max_ary = 1, types = []}) ::
  1161   ([tptp_false, tptp_true]
  1162    |> map (rpair {pred_sym = true, min_ary = 0, max_ary = 0, types = []})) @
  1163   ([tptp_equal, tptp_old_equal]
  1164    |> map (rpair {pred_sym = true, min_ary = 2, max_ary = 2, types = []}))
  1165 
  1166 fun sym_table_for_facts ctxt explicit_apply facts =
  1167   ((false, []), Symtab.empty)
  1168   |> fold (add_fact_syms_to_table ctxt explicit_apply) facts |> snd
  1169   |> fold Symtab.update default_sym_tab_entries
  1170 
  1171 fun min_arity_of sym_tab s =
  1172   case Symtab.lookup sym_tab s of
  1173     SOME ({min_ary, ...} : sym_info) => min_ary
  1174   | NONE =>
  1175     case strip_prefix_and_unascii const_prefix s of
  1176       SOME s =>
  1177       let val s = s |> unmangled_const_name |> invert_const in
  1178         if s = predicator_name then 1
  1179         else if s = app_op_name then 2
  1180         else if s = type_pred_name then 1
  1181         else 0
  1182       end
  1183     | NONE => 0
  1184 
  1185 (* True if the constant ever appears outside of the top-level position in
  1186    literals, or if it appears with different arities (e.g., because of different
  1187    type instantiations). If false, the constant always receives all of its
  1188    arguments and is used as a predicate. *)
  1189 fun is_pred_sym sym_tab s =
  1190   case Symtab.lookup sym_tab s of
  1191     SOME ({pred_sym, min_ary, max_ary, ...} : sym_info) =>
  1192     pred_sym andalso min_ary = max_ary
  1193   | NONE => false
  1194 
  1195 val predicator_combconst =
  1196   IConst (`make_fixed_const predicator_name, @{typ "bool => bool"}, [])
  1197 fun predicator tm = IApp (predicator_combconst, tm)
  1198 
  1199 fun introduce_predicators_in_iterm sym_tab tm =
  1200   case strip_iterm_comb tm of
  1201     (IConst ((s, _), _, _), _) =>
  1202     if is_pred_sym sym_tab s then tm else predicator tm
  1203   | _ => predicator tm
  1204 
  1205 fun list_app head args = fold (curry (IApp o swap)) args head
  1206 
  1207 val app_op = `make_fixed_const app_op_name
  1208 
  1209 fun explicit_app arg head =
  1210   let
  1211     val head_T = ityp_of head
  1212     val (arg_T, res_T) = dest_funT head_T
  1213     val explicit_app = IConst (app_op, head_T --> head_T, [arg_T, res_T])
  1214   in list_app explicit_app [head, arg] end
  1215 fun list_explicit_app head args = fold explicit_app args head
  1216 
  1217 fun introduce_explicit_apps_in_iterm sym_tab =
  1218   let
  1219     fun aux tm =
  1220       case strip_iterm_comb tm of
  1221         (head as IConst ((s, _), _, _), args) =>
  1222         args |> map aux
  1223              |> chop (min_arity_of sym_tab s)
  1224              |>> list_app head
  1225              |-> list_explicit_app
  1226       | (head, args) => list_explicit_app head (map aux args)
  1227   in aux end
  1228 
  1229 fun chop_fun 0 T = ([], T)
  1230   | chop_fun n (Type (@{type_name fun}, [dom_T, ran_T])) =
  1231     chop_fun (n - 1) ran_T |>> cons dom_T
  1232   | chop_fun _ _ = raise Fail "unexpected non-function"
  1233 
  1234 fun filter_type_args _ _ _ [] = []
  1235   | filter_type_args thy s arity T_args =
  1236     let
  1237       (* will throw "TYPE" for pseudo-constants *)
  1238       val U = if s = app_op_name then
  1239                 @{typ "('a => 'b) => 'a => 'b"} |> Logic.varifyT_global
  1240               else
  1241                 s |> Sign.the_const_type thy
  1242     in
  1243       case Term.add_tvarsT (U |> chop_fun arity |> snd) [] of
  1244         [] => []
  1245       | res_U_vars =>
  1246         let val U_args = (s, U) |> Sign.const_typargs thy in
  1247           U_args ~~ T_args
  1248           |> map (fn (U, T) =>
  1249                      if member (op =) res_U_vars (dest_TVar U) then T
  1250                      else dummyT)
  1251         end
  1252     end
  1253     handle TYPE _ => T_args
  1254 
  1255 fun enforce_type_arg_policy_in_iterm ctxt format type_enc =
  1256   let
  1257     val thy = Proof_Context.theory_of ctxt
  1258     fun aux arity (IApp (tm1, tm2)) = IApp (aux (arity + 1) tm1, aux 0 tm2)
  1259       | aux arity (IConst (name as (s, _), T, T_args)) =
  1260         (case strip_prefix_and_unascii const_prefix s of
  1261            NONE => (name, T_args)
  1262          | SOME s'' =>
  1263            let
  1264              val s'' = invert_const s''
  1265              fun filtered_T_args false = T_args
  1266                | filtered_T_args true = filter_type_args thy s'' arity T_args
  1267            in
  1268              case type_arg_policy type_enc s'' of
  1269                Explicit_Type_Args drop_args =>
  1270                (name, filtered_T_args drop_args)
  1271              | Mangled_Type_Args drop_args =>
  1272                (mangled_const_name format type_enc (filtered_T_args drop_args)
  1273                                    name, [])
  1274              | No_Type_Args => (name, [])
  1275            end)
  1276         |> (fn (name, T_args) => IConst (name, T, T_args))
  1277       | aux _ (IAbs (bound, tm)) = IAbs (bound, aux 0 tm)
  1278       | aux _ tm = tm
  1279   in aux 0 end
  1280 
  1281 fun repair_iterm ctxt format type_enc sym_tab =
  1282   not (is_type_enc_higher_order type_enc)
  1283   ? (introduce_explicit_apps_in_iterm sym_tab
  1284      #> introduce_predicators_in_iterm sym_tab)
  1285   #> enforce_type_arg_policy_in_iterm ctxt format type_enc
  1286 fun repair_fact ctxt format type_enc sym_tab =
  1287   update_iformula (formula_map (repair_iterm ctxt format type_enc sym_tab))
  1288 
  1289 (** Helper facts **)
  1290 
  1291 (* The Boolean indicates that a fairly sound type encoding is needed. *)
  1292 val helper_table =
  1293   [(("COMBI", false), @{thms Meson.COMBI_def}),
  1294    (("COMBK", false), @{thms Meson.COMBK_def}),
  1295    (("COMBB", false), @{thms Meson.COMBB_def}),
  1296    (("COMBC", false), @{thms Meson.COMBC_def}),
  1297    (("COMBS", false), @{thms Meson.COMBS_def}),
  1298    (("fFalse", false), [@{lemma "~ fFalse" by (unfold fFalse_def) fast}]),
  1299    (("fFalse", true), @{thms True_or_False}),
  1300    (("fTrue", false), [@{lemma "fTrue" by (unfold fTrue_def) fast}]),
  1301    (("fTrue", true), @{thms True_or_False}),
  1302    (("fNot", false),
  1303     @{thms fNot_def [THEN Meson.iff_to_disjD, THEN conjunct1]
  1304            fNot_def [THEN Meson.iff_to_disjD, THEN conjunct2]}),
  1305    (("fconj", false),
  1306     @{lemma "~ P | ~ Q | fconj P Q" "~ fconj P Q | P" "~ fconj P Q | Q"
  1307         by (unfold fconj_def) fast+}),
  1308    (("fdisj", false),
  1309     @{lemma "~ P | fdisj P Q" "~ Q | fdisj P Q" "~ fdisj P Q | P | Q"
  1310         by (unfold fdisj_def) fast+}),
  1311    (("fimplies", false),
  1312     @{lemma "P | fimplies P Q" "~ Q | fimplies P Q" "~ fimplies P Q | ~ P | Q"
  1313         by (unfold fimplies_def) fast+}),
  1314    (("fequal", true),
  1315     (* This is a lie: Higher-order equality doesn't need a sound type encoding.
  1316        However, this is done so for backward compatibility: Including the
  1317        equality helpers by default in Metis breaks a few existing proofs. *)
  1318     @{thms fequal_def [THEN Meson.iff_to_disjD, THEN conjunct1]
  1319            fequal_def [THEN Meson.iff_to_disjD, THEN conjunct2]}),
  1320    (("fAll", false), []), (*TODO: add helpers*)
  1321    (("fEx", false), []), (*TODO: add helpers*)
  1322    (("If", true), @{thms if_True if_False True_or_False})]
  1323   |> map (apsnd (map zero_var_indexes))
  1324 
  1325 val type_tag = `make_fixed_const type_tag_name
  1326 
  1327 fun type_tag_idempotence_fact () =
  1328   let
  1329     fun var s = ATerm (`I s, [])
  1330     fun tag tm = ATerm (type_tag, [var "T", tm])
  1331     val tagged_a = tag (var "A")
  1332   in
  1333     Formula (type_tag_idempotence_helper_name, Axiom,
  1334              AAtom (ATerm (`I tptp_equal, [tag tagged_a, tagged_a]))
  1335              |> close_formula_universally, isabelle_info simpN, NONE)
  1336   end
  1337 
  1338 fun should_specialize_helper type_enc t =
  1339   polymorphism_of_type_enc type_enc = Mangled_Monomorphic andalso
  1340   level_of_type_enc type_enc <> No_Types andalso
  1341   not (null (Term.hidden_polymorphism t))
  1342 
  1343 fun helper_facts_for_sym ctxt format type_enc (s, {types, ...} : sym_info) =
  1344   case strip_prefix_and_unascii const_prefix s of
  1345     SOME mangled_s =>
  1346     let
  1347       val thy = Proof_Context.theory_of ctxt
  1348       val unmangled_s = mangled_s |> unmangled_const_name
  1349       fun dub needs_fairly_sound j k =
  1350         (unmangled_s ^ "_" ^ string_of_int j ^ "_" ^ string_of_int k ^
  1351          (if mangled_s = unmangled_s then "" else "_" ^ ascii_of mangled_s) ^
  1352          (if needs_fairly_sound then typed_helper_suffix
  1353           else untyped_helper_suffix),
  1354          Helper)
  1355       fun dub_and_inst needs_fairly_sound (th, j) =
  1356         let val t = prop_of th in
  1357           if should_specialize_helper type_enc t then
  1358             map (fn T => specialize_type thy (invert_const unmangled_s, T) t)
  1359                 types
  1360           else
  1361             [t]
  1362         end
  1363         |> map (fn (k, t) => (dub needs_fairly_sound j k, t)) o tag_list 1
  1364       val make_facts = map_filter (make_fact ctxt format type_enc false)
  1365       val fairly_sound = is_type_enc_fairly_sound type_enc
  1366     in
  1367       helper_table
  1368       |> maps (fn ((helper_s, needs_fairly_sound), ths) =>
  1369                   if helper_s <> unmangled_s orelse
  1370                      (needs_fairly_sound andalso not fairly_sound) then
  1371                     []
  1372                   else
  1373                     ths ~~ (1 upto length ths)
  1374                     |> maps (dub_and_inst needs_fairly_sound)
  1375                     |> make_facts)
  1376     end
  1377   | NONE => []
  1378 fun helper_facts_for_sym_table ctxt format type_enc sym_tab =
  1379   Symtab.fold_rev (append o helper_facts_for_sym ctxt format type_enc) sym_tab
  1380                   []
  1381 
  1382 (***************************************************************)
  1383 (* Type Classes Present in the Axiom or Conjecture Clauses     *)
  1384 (***************************************************************)
  1385 
  1386 fun set_insert (x, s) = Symtab.update (x, ()) s
  1387 
  1388 fun add_classes (sorts, cset) = List.foldl set_insert cset (flat sorts)
  1389 
  1390 (* Remove this trivial type class (FIXME: similar code elsewhere) *)
  1391 fun delete_type cset = Symtab.delete_safe (the_single @{sort HOL.type}) cset
  1392 
  1393 fun classes_of_terms get_Ts =
  1394   map (map snd o get_Ts)
  1395   #> List.foldl add_classes Symtab.empty
  1396   #> delete_type #> Symtab.keys
  1397 
  1398 val tfree_classes_of_terms = classes_of_terms OldTerm.term_tfrees
  1399 val tvar_classes_of_terms = classes_of_terms OldTerm.term_tvars
  1400 
  1401 fun fold_type_constrs f (Type (s, Ts)) x =
  1402     fold (fold_type_constrs f) Ts (f (s, x))
  1403   | fold_type_constrs _ _ x = x
  1404 
  1405 (* Type constructors used to instantiate overloaded constants are the only ones
  1406    needed. *)
  1407 fun add_type_constrs_in_term thy =
  1408   let
  1409     fun add (Const (@{const_name Meson.skolem}, _) $ _) = I
  1410       | add (t $ u) = add t #> add u
  1411       | add (Const (x as (s, _))) =
  1412         if String.isPrefix skolem_const_prefix s then I
  1413         else x |> Sign.const_typargs thy |> fold (fold_type_constrs set_insert)
  1414       | add (Free (s, T)) =
  1415         if String.isPrefix polymorphic_free_prefix s then
  1416           T |> fold_type_constrs set_insert
  1417         else
  1418           I
  1419       | add (Abs (_, _, u)) = add u
  1420       | add _ = I
  1421   in add end
  1422 
  1423 fun type_constrs_of_terms thy ts =
  1424   Symtab.keys (fold (add_type_constrs_in_term thy) ts Symtab.empty)
  1425 
  1426 fun translate_formulas ctxt format prem_kind type_enc trans_lambdas preproc
  1427                        hyp_ts concl_t facts =
  1428   let
  1429     val thy = Proof_Context.theory_of ctxt
  1430     val presimp_consts = Meson.presimplified_consts ctxt
  1431     val fact_ts = facts |> map snd
  1432     (* Remove existing facts from the conjecture, as this can dramatically
  1433        boost an ATP's performance (for some reason). *)
  1434     val hyp_ts =
  1435       hyp_ts
  1436       |> map (fn t => if member (op aconv) fact_ts t then @{prop True} else t)
  1437     val facts = facts |> map (apsnd (pair Axiom))
  1438     val conjs =
  1439       map (pair prem_kind) hyp_ts @ [(Conjecture, concl_t)]
  1440       |> map2 (pair o rpair Local o string_of_int) (0 upto length hyp_ts)
  1441     val ((conjs, facts), lambdas) =
  1442       if preproc then
  1443         conjs @ facts
  1444         |> map (apsnd (apsnd (presimp_prop ctxt presimp_consts)))
  1445         |> preprocess_abstractions_in_terms trans_lambdas
  1446         |>> chop (length conjs)
  1447         |>> apfst (map (apsnd (apsnd freeze_term)))
  1448       else
  1449         ((conjs, facts), [])
  1450     val conjs = conjs |> make_conjecture ctxt format type_enc
  1451     val (fact_names, facts) =
  1452       facts
  1453       |> map_filter (fn (name, (_, t)) =>
  1454                         make_fact ctxt format type_enc true (name, t)
  1455                         |> Option.map (pair name))
  1456       |> ListPair.unzip
  1457     val lambdas =
  1458       lambdas |> map_filter (make_fact ctxt format type_enc true o apsnd snd)
  1459     val all_ts = concl_t :: hyp_ts @ fact_ts
  1460     val subs = tfree_classes_of_terms all_ts
  1461     val supers = tvar_classes_of_terms all_ts
  1462     val tycons = type_constrs_of_terms thy all_ts
  1463     val (supers, arity_clauses) =
  1464       if level_of_type_enc type_enc = No_Types then ([], [])
  1465       else make_arity_clauses thy tycons supers
  1466     val class_rel_clauses = make_class_rel_clauses thy subs supers
  1467   in
  1468     (fact_names |> map single,
  1469      (conjs, facts @ lambdas, class_rel_clauses, arity_clauses))
  1470   end
  1471 
  1472 fun fo_literal_from_type_literal (TyLitVar (class, name)) =
  1473     (true, ATerm (class, [ATerm (name, [])]))
  1474   | fo_literal_from_type_literal (TyLitFree (class, name)) =
  1475     (true, ATerm (class, [ATerm (name, [])]))
  1476 
  1477 fun formula_from_fo_literal (pos, t) = AAtom t |> not pos ? mk_anot
  1478 
  1479 val type_pred = `make_fixed_const type_pred_name
  1480 
  1481 fun type_pred_iterm ctxt format type_enc T tm =
  1482   IApp (IConst (type_pred, T --> @{typ bool}, [T])
  1483         |> enforce_type_arg_policy_in_iterm ctxt format type_enc, tm)
  1484 
  1485 fun is_var_positively_naked_in_term _ (SOME false) _ accum = accum
  1486   | is_var_positively_naked_in_term name _ (ATerm ((s, _), tms)) accum =
  1487     accum orelse (is_tptp_equal s andalso member (op =) tms (ATerm (name, [])))
  1488   | is_var_positively_naked_in_term _ _ _ _ = true
  1489 fun should_predicate_on_var_in_formula pos phi (SOME true) name =
  1490     formula_fold pos (is_var_positively_naked_in_term name) phi false
  1491   | should_predicate_on_var_in_formula _ _ _ _ = true
  1492 
  1493 fun mk_aterm format type_enc name T_args args =
  1494   ATerm (name, map_filter (ho_term_for_type_arg format type_enc) T_args @ args)
  1495 
  1496 fun tag_with_type ctxt format nonmono_Ts type_enc pos T tm =
  1497   IConst (type_tag, T --> T, [T])
  1498   |> enforce_type_arg_policy_in_iterm ctxt format type_enc
  1499   |> ho_term_from_iterm ctxt format nonmono_Ts type_enc (Top_Level pos)
  1500   |> (fn ATerm (s, tms) => ATerm (s, tms @ [tm])
  1501        | _ => raise Fail "unexpected lambda-abstraction")
  1502 and ho_term_from_iterm ctxt format nonmono_Ts type_enc =
  1503   let
  1504     fun aux site u =
  1505       let
  1506         val (head, args) = strip_iterm_comb u
  1507         val pos =
  1508           case site of
  1509             Top_Level pos => pos
  1510           | Eq_Arg pos => pos
  1511           | Elsewhere => NONE
  1512         val t =
  1513           case head of
  1514             IConst (name as (s, _), _, T_args) =>
  1515             let
  1516               val arg_site = if is_tptp_equal s then Eq_Arg pos else Elsewhere
  1517             in
  1518               mk_aterm format type_enc name T_args (map (aux arg_site) args)
  1519             end
  1520           | IVar (name, _) =>
  1521             mk_aterm format type_enc name [] (map (aux Elsewhere) args)
  1522           | IAbs ((name, T), tm) =>
  1523             AAbs ((name, ho_type_from_typ format type_enc true 0 T),
  1524                   aux Elsewhere tm)
  1525           | IApp _ => raise Fail "impossible \"IApp\""
  1526         val T = ityp_of u
  1527       in
  1528         t |> (if should_tag_with_type ctxt nonmono_Ts type_enc site u T then
  1529                 tag_with_type ctxt format nonmono_Ts type_enc pos T
  1530               else
  1531                 I)
  1532       end
  1533   in aux end
  1534 and formula_from_iformula ctxt format nonmono_Ts type_enc
  1535                           should_predicate_on_var =
  1536   let
  1537     val do_term = ho_term_from_iterm ctxt format nonmono_Ts type_enc o Top_Level
  1538     val do_bound_type =
  1539       case type_enc of
  1540         Simple_Types (_, level) =>
  1541         homogenized_type ctxt nonmono_Ts level 0
  1542         #> ho_type_from_typ format type_enc false 0 #> SOME
  1543       | _ => K NONE
  1544     fun do_out_of_bound_type pos phi universal (name, T) =
  1545       if should_predicate_on_type ctxt nonmono_Ts type_enc
  1546              (fn () => should_predicate_on_var pos phi universal name) T then
  1547         IVar (name, T)
  1548         |> type_pred_iterm ctxt format type_enc T
  1549         |> do_term pos |> AAtom |> SOME
  1550       else
  1551         NONE
  1552     fun do_formula pos (AQuant (q, xs, phi)) =
  1553         let
  1554           val phi = phi |> do_formula pos
  1555           val universal = Option.map (q = AExists ? not) pos
  1556         in
  1557           AQuant (q, xs |> map (apsnd (fn NONE => NONE
  1558                                         | SOME T => do_bound_type T)),
  1559                   (if q = AForall then mk_ahorn else fold_rev (mk_aconn AAnd))
  1560                       (map_filter
  1561                            (fn (_, NONE) => NONE
  1562                              | (s, SOME T) =>
  1563                                do_out_of_bound_type pos phi universal (s, T))
  1564                            xs)
  1565                       phi)
  1566         end
  1567       | do_formula pos (AConn conn) = aconn_map pos do_formula conn
  1568       | do_formula pos (AAtom tm) = AAtom (do_term pos tm)
  1569   in do_formula end
  1570 
  1571 fun bound_tvars type_enc Ts =
  1572   mk_ahorn (map (formula_from_fo_literal o fo_literal_from_type_literal)
  1573                 (type_literals_for_types type_enc add_sorts_on_tvar Ts))
  1574 
  1575 (* Each fact is given a unique fact number to avoid name clashes (e.g., because
  1576    of monomorphization). The TPTP explicitly forbids name clashes, and some of
  1577    the remote provers might care. *)
  1578 fun formula_line_for_fact ctxt format prefix encode freshen pos nonmono_Ts
  1579         type_enc (j, {name, locality, kind, iformula, atomic_types}) =
  1580   (prefix ^ (if freshen then string_of_int j ^ "_" else "") ^ encode name, kind,
  1581    iformula
  1582    |> close_iformula_universally
  1583    |> formula_from_iformula ctxt format nonmono_Ts type_enc
  1584                             should_predicate_on_var_in_formula
  1585                             (if pos then SOME true else NONE)
  1586    |> bound_tvars type_enc atomic_types
  1587    |> close_formula_universally,
  1588    NONE,
  1589    case locality of
  1590      Intro => isabelle_info introN
  1591    | Elim => isabelle_info elimN
  1592    | Simp => isabelle_info simpN
  1593    | _ => NONE)
  1594   |> Formula
  1595 
  1596 fun formula_line_for_class_rel_clause ({name, subclass, superclass, ...}
  1597                                        : class_rel_clause) =
  1598   let val ty_arg = ATerm (`I "T", []) in
  1599     Formula (class_rel_clause_prefix ^ ascii_of name, Axiom,
  1600              AConn (AImplies, [AAtom (ATerm (subclass, [ty_arg])),
  1601                                AAtom (ATerm (superclass, [ty_arg]))])
  1602              |> close_formula_universally, isabelle_info introN, NONE)
  1603   end
  1604 
  1605 fun fo_literal_from_arity_literal (TConsLit (c, t, args)) =
  1606     (true, ATerm (c, [ATerm (t, map (fn arg => ATerm (arg, [])) args)]))
  1607   | fo_literal_from_arity_literal (TVarLit (c, sort)) =
  1608     (false, ATerm (c, [ATerm (sort, [])]))
  1609 
  1610 fun formula_line_for_arity_clause ({name, prem_lits, concl_lits, ...}
  1611                                    : arity_clause) =
  1612   Formula (arity_clause_prefix ^ name, Axiom,
  1613            mk_ahorn (map (formula_from_fo_literal o apfst not
  1614                           o fo_literal_from_arity_literal) prem_lits)
  1615                     (formula_from_fo_literal
  1616                          (fo_literal_from_arity_literal concl_lits))
  1617            |> close_formula_universally, isabelle_info introN, NONE)
  1618 
  1619 fun formula_line_for_conjecture ctxt format nonmono_Ts type_enc
  1620         ({name, kind, iformula, atomic_types, ...} : translated_formula) =
  1621   Formula (conjecture_prefix ^ name, kind,
  1622            formula_from_iformula ctxt format nonmono_Ts type_enc
  1623                should_predicate_on_var_in_formula (SOME false)
  1624                (close_iformula_universally iformula)
  1625            |> bound_tvars type_enc atomic_types
  1626            |> close_formula_universally, NONE, NONE)
  1627 
  1628 fun free_type_literals type_enc ({atomic_types, ...} : translated_formula) =
  1629   atomic_types |> type_literals_for_types type_enc add_sorts_on_tfree
  1630                |> map fo_literal_from_type_literal
  1631 
  1632 fun formula_line_for_free_type j lit =
  1633   Formula (tfree_clause_prefix ^ string_of_int j, Hypothesis,
  1634            formula_from_fo_literal lit, NONE, NONE)
  1635 fun formula_lines_for_free_types type_enc facts =
  1636   let
  1637     val litss = map (free_type_literals type_enc) facts
  1638     val lits = fold (union (op =)) litss []
  1639   in map2 formula_line_for_free_type (0 upto length lits - 1) lits end
  1640 
  1641 (** Symbol declarations **)
  1642 
  1643 fun should_declare_sym type_enc pred_sym s =
  1644   is_tptp_user_symbol s andalso not (String.isPrefix bound_var_prefix s) andalso
  1645   (case type_enc of
  1646      Simple_Types _ => true
  1647    | Tags (_, _, Lightweight) => true
  1648    | _ => not pred_sym)
  1649 
  1650 fun sym_decl_table_for_facts ctxt type_enc repaired_sym_tab (conjs, facts) =
  1651   let
  1652     fun add_iterm in_conj tm =
  1653       let val (head, args) = strip_iterm_comb tm in
  1654         (case head of
  1655            IConst ((s, s'), T, T_args) =>
  1656            let val pred_sym = is_pred_sym repaired_sym_tab s in
  1657              if should_declare_sym type_enc pred_sym s then
  1658                Symtab.map_default (s, [])
  1659                    (insert_type ctxt #3 (s', T_args, T, pred_sym, length args,
  1660                                          in_conj))
  1661              else
  1662                I
  1663            end
  1664          | IAbs (_, tm) => add_iterm in_conj tm
  1665          | _ => I)
  1666         #> fold (add_iterm in_conj) args
  1667       end
  1668     fun add_fact in_conj = fact_lift (formula_fold NONE (K (add_iterm in_conj)))
  1669   in
  1670     Symtab.empty
  1671     |> is_type_enc_fairly_sound type_enc
  1672        ? (fold (add_fact true) conjs #> fold (add_fact false) facts)
  1673   end
  1674 
  1675 (* This inference is described in section 2.3 of Claessen et al.'s "Sorting it
  1676    out with monotonicity" paper presented at CADE 2011. *)
  1677 fun add_iterm_nonmonotonic_types _ _ _ _ (SOME false) _ = I
  1678   | add_iterm_nonmonotonic_types ctxt level sound locality _
  1679         (IApp (IApp (IConst ((s, _), Type (_, [T, _]), _), tm1), tm2)) =
  1680     (is_tptp_equal s andalso exists is_var_or_bound_var [tm1, tm2] andalso
  1681      (case level of
  1682         Noninf_Nonmono_Types =>
  1683         not (is_locality_global locality) orelse
  1684         not (is_type_surely_infinite ctxt sound T)
  1685       | Fin_Nonmono_Types => is_type_surely_finite ctxt false T
  1686       | _ => true)) ? insert_type ctxt I (deep_freeze_type T)
  1687   | add_iterm_nonmonotonic_types _ _ _ _ _ _ = I
  1688 fun add_fact_nonmonotonic_types ctxt level sound
  1689         ({kind, locality, iformula, ...} : translated_formula) =
  1690   formula_fold (SOME (kind <> Conjecture))
  1691                (add_iterm_nonmonotonic_types ctxt level sound locality)
  1692                iformula
  1693 fun nonmonotonic_types_for_facts ctxt type_enc sound facts =
  1694   let val level = level_of_type_enc type_enc in
  1695     if level = Noninf_Nonmono_Types orelse level = Fin_Nonmono_Types then
  1696       [] |> fold (add_fact_nonmonotonic_types ctxt level sound) facts
  1697          (* We must add "bool" in case the helper "True_or_False" is added
  1698             later. In addition, several places in the code rely on the list of
  1699             nonmonotonic types not being empty. *)
  1700          |> insert_type ctxt I @{typ bool}
  1701     else
  1702       []
  1703   end
  1704 
  1705 fun decl_line_for_sym ctxt format nonmono_Ts type_enc s
  1706                       (s', T_args, T, pred_sym, ary, _) =
  1707   let
  1708     val (T_arg_Ts, level) =
  1709       case type_enc of
  1710         Simple_Types (_, level) => ([], level)
  1711       | _ => (replicate (length T_args) homo_infinite_type, No_Types)
  1712   in
  1713     Decl (sym_decl_prefix ^ s, (s, s'),
  1714           (T_arg_Ts ---> (T |> homogenized_type ctxt nonmono_Ts level ary))
  1715           |> ho_type_from_typ format type_enc pred_sym (length T_arg_Ts + ary))
  1716   end
  1717 
  1718 fun formula_line_for_preds_sym_decl ctxt format conj_sym_kind nonmono_Ts
  1719         poly_nonmono_Ts type_enc n s j (s', T_args, T, _, ary, in_conj) =
  1720   let
  1721     val (kind, maybe_negate) =
  1722       if in_conj then (conj_sym_kind, conj_sym_kind = Conjecture ? mk_anot)
  1723       else (Axiom, I)
  1724     val (arg_Ts, res_T) = chop_fun ary T
  1725     val num_args = length arg_Ts
  1726     val bound_names =
  1727       1 upto num_args |> map (`I o make_bound_var o string_of_int)
  1728     val bounds =
  1729       bound_names ~~ arg_Ts |> map (fn (name, T) => IConst (name, T, []))
  1730     val sym_needs_arg_types = exists (curry (op =) dummyT) T_args
  1731     fun should_keep_arg_type T =
  1732       sym_needs_arg_types orelse
  1733       not (should_predicate_on_type ctxt nonmono_Ts type_enc (K false) T)
  1734     val bound_Ts =
  1735       arg_Ts |> map (fn T => if should_keep_arg_type T then SOME T else NONE)
  1736   in
  1737     Formula (preds_sym_formula_prefix ^ s ^
  1738              (if n > 1 then "_" ^ string_of_int j else ""), kind,
  1739              IConst ((s, s'), T, T_args)
  1740              |> fold (curry (IApp o swap)) bounds
  1741              |> type_pred_iterm ctxt format type_enc res_T
  1742              |> AAtom |> mk_aquant AForall (bound_names ~~ bound_Ts)
  1743              |> formula_from_iformula ctxt format poly_nonmono_Ts type_enc
  1744                                       (K (K (K (K true)))) (SOME true)
  1745              |> n > 1 ? bound_tvars type_enc (atyps_of T)
  1746              |> close_formula_universally
  1747              |> maybe_negate,
  1748              isabelle_info introN, NONE)
  1749   end
  1750 
  1751 fun formula_lines_for_lightweight_tags_sym_decl ctxt format conj_sym_kind
  1752         poly_nonmono_Ts type_enc n s
  1753         (j, (s', T_args, T, pred_sym, ary, in_conj)) =
  1754   let
  1755     val ident_base =
  1756       lightweight_tags_sym_formula_prefix ^ s ^
  1757       (if n > 1 then "_" ^ string_of_int j else "")
  1758     val (kind, maybe_negate) =
  1759       if in_conj then (conj_sym_kind, conj_sym_kind = Conjecture ? mk_anot)
  1760       else (Axiom, I)
  1761     val (arg_Ts, res_T) = chop_fun ary T
  1762     val bound_names =
  1763       1 upto length arg_Ts |> map (`I o make_bound_var o string_of_int)
  1764     val bounds = bound_names |> map (fn name => ATerm (name, []))
  1765     val cst = mk_aterm format type_enc (s, s') T_args
  1766     val atomic_Ts = atyps_of T
  1767     fun eq tms =
  1768       (if pred_sym then AConn (AIff, map AAtom tms)
  1769        else AAtom (ATerm (`I tptp_equal, tms)))
  1770       |> bound_tvars type_enc atomic_Ts
  1771       |> close_formula_universally
  1772       |> maybe_negate
  1773     (* See also "should_tag_with_type". *)
  1774     fun should_encode T =
  1775       should_encode_type ctxt poly_nonmono_Ts All_Types T orelse
  1776       (case type_enc of
  1777          Tags (Polymorphic, level, Lightweight) =>
  1778          level <> All_Types andalso Monomorph.typ_has_tvars T
  1779        | _ => false)
  1780     val tag_with = tag_with_type ctxt format poly_nonmono_Ts type_enc NONE
  1781     val add_formula_for_res =
  1782       if should_encode res_T then
  1783         cons (Formula (ident_base ^ "_res", kind,
  1784                        eq [tag_with res_T (cst bounds), cst bounds],
  1785                        isabelle_info simpN, NONE))
  1786       else
  1787         I
  1788     fun add_formula_for_arg k =
  1789       let val arg_T = nth arg_Ts k in
  1790         if should_encode arg_T then
  1791           case chop k bounds of
  1792             (bounds1, bound :: bounds2) =>
  1793             cons (Formula (ident_base ^ "_arg" ^ string_of_int (k + 1), kind,
  1794                            eq [cst (bounds1 @ tag_with arg_T bound :: bounds2),
  1795                                cst bounds],
  1796                            isabelle_info simpN, NONE))
  1797           | _ => raise Fail "expected nonempty tail"
  1798         else
  1799           I
  1800       end
  1801   in
  1802     [] |> not pred_sym ? add_formula_for_res
  1803        |> fold add_formula_for_arg (ary - 1 downto 0)
  1804   end
  1805 
  1806 fun result_type_of_decl (_, _, T, _, ary, _) = chop_fun ary T |> snd
  1807 
  1808 fun problem_lines_for_sym_decls ctxt format conj_sym_kind nonmono_Ts
  1809                                 poly_nonmono_Ts type_enc (s, decls) =
  1810   case type_enc of
  1811     Simple_Types _ =>
  1812     decls |> map (decl_line_for_sym ctxt format nonmono_Ts type_enc s)
  1813   | Preds _ =>
  1814     let
  1815       val decls =
  1816         case decls of
  1817           decl :: (decls' as _ :: _) =>
  1818           let val T = result_type_of_decl decl in
  1819             if forall (curry (type_instance ctxt o swap) T
  1820                        o result_type_of_decl) decls' then
  1821               [decl]
  1822             else
  1823               decls
  1824           end
  1825         | _ => decls
  1826       val n = length decls
  1827       val decls =
  1828         decls |> filter (should_predicate_on_type ctxt poly_nonmono_Ts type_enc
  1829                                                   (K true)
  1830                          o result_type_of_decl)
  1831     in
  1832       (0 upto length decls - 1, decls)
  1833       |-> map2 (formula_line_for_preds_sym_decl ctxt format conj_sym_kind
  1834                    nonmono_Ts poly_nonmono_Ts type_enc n s)
  1835     end
  1836   | Tags (_, _, heaviness) =>
  1837     (case heaviness of
  1838        Heavyweight => []
  1839      | Lightweight =>
  1840        let val n = length decls in
  1841          (0 upto n - 1 ~~ decls)
  1842          |> maps (formula_lines_for_lightweight_tags_sym_decl ctxt format
  1843                       conj_sym_kind poly_nonmono_Ts type_enc n s)
  1844        end)
  1845 
  1846 fun problem_lines_for_sym_decl_table ctxt format conj_sym_kind nonmono_Ts
  1847                                      poly_nonmono_Ts type_enc sym_decl_tab =
  1848   sym_decl_tab
  1849   |> Symtab.dest
  1850   |> sort_wrt fst
  1851   |> rpair []
  1852   |-> fold_rev (append o problem_lines_for_sym_decls ctxt format conj_sym_kind
  1853                              nonmono_Ts poly_nonmono_Ts type_enc)
  1854 
  1855 fun needs_type_tag_idempotence (Tags (poly, level, heaviness)) =
  1856     poly <> Mangled_Monomorphic andalso
  1857     ((level = All_Types andalso heaviness = Lightweight) orelse
  1858      level = Noninf_Nonmono_Types orelse level = Fin_Nonmono_Types)
  1859   | needs_type_tag_idempotence _ = false
  1860 
  1861 fun offset_of_heading_in_problem _ [] j = j
  1862   | offset_of_heading_in_problem needle ((heading, lines) :: problem) j =
  1863     if heading = needle then j
  1864     else offset_of_heading_in_problem needle problem (j + length lines)
  1865 
  1866 val implicit_declsN = "Should-be-implicit typings"
  1867 val explicit_declsN = "Explicit typings"
  1868 val factsN = "Relevant facts"
  1869 val class_relsN = "Class relationships"
  1870 val aritiesN = "Arities"
  1871 val helpersN = "Helper facts"
  1872 val conjsN = "Conjectures"
  1873 val free_typesN = "Type variables"
  1874 
  1875 val explicit_apply = NONE (* for experiments *)
  1876 
  1877 fun prepare_atp_problem ctxt format conj_sym_kind prem_kind type_enc sound
  1878         exporter trans_lambdas readable_names preproc hyp_ts concl_t facts =
  1879   let
  1880     val (format, type_enc) = choose_format [format] type_enc
  1881     val (fact_names, (conjs, facts, class_rel_clauses, arity_clauses)) =
  1882       translate_formulas ctxt format prem_kind type_enc trans_lambdas preproc
  1883                          hyp_ts concl_t facts
  1884     val sym_tab = conjs @ facts |> sym_table_for_facts ctxt explicit_apply
  1885     val nonmono_Ts =
  1886       conjs @ facts |> nonmonotonic_types_for_facts ctxt type_enc sound
  1887     val repair = repair_fact ctxt format type_enc sym_tab
  1888     val (conjs, facts) = (conjs, facts) |> pairself (map repair)
  1889     val repaired_sym_tab =
  1890       conjs @ facts |> sym_table_for_facts ctxt (SOME false)
  1891     val helpers =
  1892       repaired_sym_tab |> helper_facts_for_sym_table ctxt format type_enc
  1893                        |> map repair
  1894     val poly_nonmono_Ts =
  1895       if null nonmono_Ts orelse nonmono_Ts = [@{typ bool}] orelse
  1896          polymorphism_of_type_enc type_enc <> Polymorphic then
  1897         nonmono_Ts
  1898       else
  1899         [TVar (("'a", 0), HOLogic.typeS)]
  1900     val sym_decl_lines =
  1901       (conjs, helpers @ facts)
  1902       |> sym_decl_table_for_facts ctxt type_enc repaired_sym_tab
  1903       |> problem_lines_for_sym_decl_table ctxt format conj_sym_kind nonmono_Ts
  1904                                                poly_nonmono_Ts type_enc
  1905     val helper_lines =
  1906       0 upto length helpers - 1 ~~ helpers
  1907       |> map (formula_line_for_fact ctxt format helper_prefix I false true
  1908                                     poly_nonmono_Ts type_enc)
  1909       |> (if needs_type_tag_idempotence type_enc then
  1910             cons (type_tag_idempotence_fact ())
  1911           else
  1912             I)
  1913     (* Reordering these might confuse the proof reconstruction code or the SPASS
  1914        FLOTTER hack. *)
  1915     val problem =
  1916       [(explicit_declsN, sym_decl_lines),
  1917        (factsN,
  1918         map (formula_line_for_fact ctxt format fact_prefix ascii_of
  1919                                    (not exporter) (not exporter) nonmono_Ts
  1920                                    type_enc)
  1921             (0 upto length facts - 1 ~~ facts)),
  1922        (class_relsN, map formula_line_for_class_rel_clause class_rel_clauses),
  1923        (aritiesN, map formula_line_for_arity_clause arity_clauses),
  1924        (helpersN, helper_lines),
  1925        (conjsN,
  1926         map (formula_line_for_conjecture ctxt format nonmono_Ts type_enc)
  1927             conjs),
  1928        (free_typesN, formula_lines_for_free_types type_enc (facts @ conjs))]
  1929     val problem =
  1930       problem
  1931       |> (case format of
  1932             CNF => ensure_cnf_problem
  1933           | CNF_UEQ => filter_cnf_ueq_problem
  1934           | _ => I)
  1935       |> (if is_format_typed format then
  1936             declare_undeclared_syms_in_atp_problem type_decl_prefix
  1937                                                    implicit_declsN
  1938           else
  1939             I)
  1940     val (problem, pool) = problem |> nice_atp_problem readable_names
  1941     val helpers_offset = offset_of_heading_in_problem helpersN problem 0
  1942     val typed_helpers =
  1943       map_filter (fn (j, {name, ...}) =>
  1944                      if String.isSuffix typed_helper_suffix name then SOME j
  1945                      else NONE)
  1946                  ((helpers_offset + 1 upto helpers_offset + length helpers)
  1947                   ~~ helpers)
  1948     fun add_sym_arity (s, {min_ary, ...} : sym_info) =
  1949       if min_ary > 0 then
  1950         case strip_prefix_and_unascii const_prefix s of
  1951           SOME s => Symtab.insert (op =) (s, min_ary)
  1952         | NONE => I
  1953       else
  1954         I
  1955   in
  1956     (problem,
  1957      case pool of SOME the_pool => snd the_pool | NONE => Symtab.empty,
  1958      offset_of_heading_in_problem conjsN problem 0,
  1959      offset_of_heading_in_problem factsN problem 0,
  1960      fact_names |> Vector.fromList,
  1961      typed_helpers,
  1962      Symtab.empty |> Symtab.fold add_sym_arity sym_tab)
  1963   end
  1964 
  1965 (* FUDGE *)
  1966 val conj_weight = 0.0
  1967 val hyp_weight = 0.1
  1968 val fact_min_weight = 0.2
  1969 val fact_max_weight = 1.0
  1970 val type_info_default_weight = 0.8
  1971 
  1972 fun add_term_weights weight (ATerm (s, tms)) =
  1973     is_tptp_user_symbol s ? Symtab.default (s, weight)
  1974     #> fold (add_term_weights weight) tms
  1975   | add_term_weights weight (AAbs (_, tm)) = add_term_weights weight tm
  1976 fun add_problem_line_weights weight (Formula (_, _, phi, _, _)) =
  1977     formula_fold NONE (K (add_term_weights weight)) phi
  1978   | add_problem_line_weights _ _ = I
  1979 
  1980 fun add_conjectures_weights [] = I
  1981   | add_conjectures_weights conjs =
  1982     let val (hyps, conj) = split_last conjs in
  1983       add_problem_line_weights conj_weight conj
  1984       #> fold (add_problem_line_weights hyp_weight) hyps
  1985     end
  1986 
  1987 fun add_facts_weights facts =
  1988   let
  1989     val num_facts = length facts
  1990     fun weight_of j =
  1991       fact_min_weight + (fact_max_weight - fact_min_weight) * Real.fromInt j
  1992                         / Real.fromInt num_facts
  1993   in
  1994     map weight_of (0 upto num_facts - 1) ~~ facts
  1995     |> fold (uncurry add_problem_line_weights)
  1996   end
  1997 
  1998 (* Weights are from 0.0 (most important) to 1.0 (least important). *)
  1999 fun atp_problem_weights problem =
  2000   let val get = these o AList.lookup (op =) problem in
  2001     Symtab.empty
  2002     |> add_conjectures_weights (get free_typesN @ get conjsN)
  2003     |> add_facts_weights (get factsN)
  2004     |> fold (fold (add_problem_line_weights type_info_default_weight) o get)
  2005             [explicit_declsN, class_relsN, aritiesN]
  2006     |> Symtab.dest
  2007     |> sort (prod_ord Real.compare string_ord o pairself swap)
  2008   end
  2009 
  2010 end;