src/HOL/Tools/Sledgehammer/metis_clauses.ML
changeset 37578 9367cb36b1c4
parent 37577 5379f41a1322
child 37616 c8d2d84d6011
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/Sledgehammer/metis_clauses.ML	Fri Jun 25 17:08:39 2010 +0200
@@ -0,0 +1,685 @@
+(*  Title:      HOL/Tools/Sledgehammer/metis_clauses.ML
+    Author:     Jia Meng, Cambridge University Computer Laboratory
+    Author:     Jasmin Blanchette, TU Muenchen
+
+Storing/printing FOL clauses and arity clauses.  Typed equality is
+treated differently.
+*)
+
+signature METIS_CLAUSES =
+sig
+  type cnf_thm = Clausifier.cnf_thm
+  type name = string * string
+  type name_pool = string Symtab.table * string Symtab.table
+  datatype kind = Axiom | Conjecture
+  datatype type_literal =
+    TyLitVar of string * name |
+    TyLitFree of string * name
+  datatype arLit =
+      TConsLit of class * string * string list
+    | TVarLit of class * string
+  datatype arity_clause = ArityClause of
+   {axiom_name: string, conclLit: arLit, premLits: arLit list}
+  datatype classrel_clause = ClassrelClause of
+   {axiom_name: string, subclass: class, superclass: class}
+  datatype combtyp =
+    TyVar of name |
+    TyFree of name |
+    TyConstr of name * combtyp list
+  datatype combterm =
+    CombConst of name * combtyp * combtyp list (* Const and Free *) |
+    CombVar of name * combtyp |
+    CombApp of combterm * combterm
+  datatype literal = Literal of bool * combterm
+  datatype hol_clause =
+    HOLClause of {clause_id: int, axiom_name: string, th: thm, kind: kind,
+                  literals: literal list, ctypes_sorts: typ list}
+  exception TRIVIAL of unit
+
+  val type_wrapper_name : string
+  val schematic_var_prefix: string
+  val fixed_var_prefix: string
+  val tvar_prefix: string
+  val tfree_prefix: string
+  val const_prefix: string
+  val tconst_prefix: string
+  val class_prefix: string
+  val union_all: ''a list list -> ''a list
+  val invert_const: string -> string
+  val ascii_of: string -> string
+  val undo_ascii_of: string -> string
+  val strip_prefix: string -> string -> string option
+  val make_schematic_var : string * int -> string
+  val make_fixed_var : string -> string
+  val make_schematic_type_var : string * int -> string
+  val make_fixed_type_var : string -> string
+  val make_fixed_const : string -> string
+  val make_fixed_type_const : string -> string
+  val make_type_class : string -> string
+  val empty_name_pool : bool -> name_pool option
+  val pool_map : ('a -> 'b -> 'c * 'b) -> 'a list -> 'b -> 'c list * 'b
+  val nice_name : name -> name_pool option -> string * name_pool option
+  val type_literals_for_types : typ list -> type_literal list
+  val make_classrel_clauses: theory -> class list -> class list -> classrel_clause list
+  val make_arity_clauses: theory -> string list -> class list -> class list * arity_clause list
+  val type_of_combterm : combterm -> combtyp
+  val strip_combterm_comb : combterm -> combterm * combterm list
+  val literals_of_term : theory -> term -> literal list * typ list
+  val conceal_skolem_somes :
+    int -> (string * term) list -> term -> (string * term) list * term
+  val is_quasi_fol_theorem : theory -> thm -> bool
+  val make_clause_table : (thm * 'a) list -> (thm * 'a) Termtab.table
+  val tfree_classes_of_terms : term list -> string list
+  val tvar_classes_of_terms : term list -> string list
+  val type_consts_of_terms : theory -> term list -> string list
+  val prepare_clauses :
+    bool -> thm list -> cnf_thm list -> cnf_thm list -> theory
+    -> string vector
+       * (hol_clause list * hol_clause list * hol_clause list * hol_clause list
+          * classrel_clause list * arity_clause list)
+end
+
+structure Metis_Clauses : METIS_CLAUSES =
+struct
+
+open Clausifier
+
+val type_wrapper_name = "ti"
+
+val schematic_var_prefix = "V_";
+val fixed_var_prefix = "v_";
+
+val tvar_prefix = "T_";
+val tfree_prefix = "t_";
+
+val classrel_clause_prefix = "clsrel_";
+
+val const_prefix = "c_";
+val tconst_prefix = "tc_";
+val class_prefix = "class_";
+
+fun union_all xss = fold (union (op =)) xss []
+
+(* Readable names for the more common symbolic functions. Do not mess with the
+   last nine entries of the table unless you know what you are doing. *)
+val const_trans_table =
+  Symtab.make [(@{const_name "op ="}, "equal"),
+               (@{const_name "op &"}, "and"),
+               (@{const_name "op |"}, "or"),
+               (@{const_name "op -->"}, "implies"),
+               (@{const_name "op :"}, "in"),
+               (@{const_name fequal}, "fequal"),
+               (@{const_name COMBI}, "COMBI"),
+               (@{const_name COMBK}, "COMBK"),
+               (@{const_name COMBB}, "COMBB"),
+               (@{const_name COMBC}, "COMBC"),
+               (@{const_name COMBS}, "COMBS"),
+               (@{const_name True}, "True"),
+               (@{const_name False}, "False"),
+               (@{const_name If}, "If"),
+               (@{type_name "*"}, "prod"),
+               (@{type_name "+"}, "sum")]
+
+(* Invert the table of translations between Isabelle and ATPs. *)
+val const_trans_table_inv =
+  Symtab.update ("fequal", @{const_name "op ="})
+                (Symtab.make (map swap (Symtab.dest const_trans_table)))
+
+val invert_const = perhaps (Symtab.lookup const_trans_table_inv)
+
+(*Escaping of special characters.
+  Alphanumeric characters are left unchanged.
+  The character _ goes to __
+  Characters in the range ASCII space to / go to _A to _P, respectively.
+  Other printing characters go to _nnn where nnn is the decimal ASCII code.*)
+val A_minus_space = Char.ord #"A" - Char.ord #" ";
+
+fun stringN_of_int 0 _ = ""
+  | stringN_of_int k n = stringN_of_int (k-1) (n div 10) ^ Int.toString (n mod 10);
+
+fun ascii_of_c c =
+  if Char.isAlphaNum c then String.str c
+  else if c = #"_" then "__"
+  else if #" " <= c andalso c <= #"/"
+       then "_" ^ String.str (Char.chr (Char.ord c + A_minus_space))
+  else if Char.isPrint c
+       then ("_" ^ stringN_of_int 3 (Char.ord c))  (*fixed width, in case more digits follow*)
+  else ""
+
+val ascii_of = String.translate ascii_of_c;
+
+(** Remove ASCII armouring from names in proof files **)
+
+(*We don't raise error exceptions because this code can run inside the watcher.
+  Also, the errors are "impossible" (hah!)*)
+fun undo_ascii_aux rcs [] = String.implode(rev rcs)
+  | undo_ascii_aux rcs [#"_"] = undo_ascii_aux (#"_"::rcs) []  (*ERROR*)
+      (*Three types of _ escapes: __, _A to _P, _nnn*)
+  | undo_ascii_aux rcs (#"_" :: #"_" :: cs) = undo_ascii_aux (#"_"::rcs) cs
+  | undo_ascii_aux rcs (#"_" :: c :: cs) =
+      if #"A" <= c andalso c<= #"P"  (*translation of #" " to #"/"*)
+      then undo_ascii_aux (Char.chr(Char.ord c - A_minus_space) :: rcs) cs
+      else
+        let val digits = List.take (c::cs, 3) handle Subscript => []
+        in
+            case Int.fromString (String.implode digits) of
+                NONE => undo_ascii_aux (c:: #"_"::rcs) cs  (*ERROR*)
+              | SOME n => undo_ascii_aux (Char.chr n :: rcs) (List.drop (cs, 2))
+        end
+  | undo_ascii_aux rcs (c::cs) = undo_ascii_aux (c::rcs) cs;
+
+val undo_ascii_of = undo_ascii_aux [] o String.explode;
+
+(* If string s has the prefix s1, return the result of deleting it,
+   un-ASCII'd. *)
+fun strip_prefix s1 s =
+  if String.isPrefix s1 s then
+    SOME (undo_ascii_of (String.extract (s, size s1, NONE)))
+  else
+    NONE
+
+(*Remove the initial ' character from a type variable, if it is present*)
+fun trim_type_var s =
+  if s <> "" andalso String.sub(s,0) = #"'" then String.extract(s,1,NONE)
+  else error ("trim_type: Malformed type variable encountered: " ^ s);
+
+fun ascii_of_indexname (v,0) = ascii_of v
+  | ascii_of_indexname (v,i) = ascii_of v ^ "_" ^ Int.toString i;
+
+fun make_schematic_var v = schematic_var_prefix ^ (ascii_of_indexname v);
+fun make_fixed_var x = fixed_var_prefix ^ (ascii_of x);
+
+fun make_schematic_type_var (x,i) =
+      tvar_prefix ^ (ascii_of_indexname (trim_type_var x,i));
+fun make_fixed_type_var x = tfree_prefix ^ (ascii_of (trim_type_var x));
+
+fun lookup_const c =
+  case Symtab.lookup const_trans_table c of
+    SOME c' => c'
+  | NONE => ascii_of c
+
+(* "op =" MUST BE "equal" because it's built into ATPs. *)
+fun make_fixed_const @{const_name "op ="} = "equal"
+  | make_fixed_const c = const_prefix ^ lookup_const c
+
+fun make_fixed_type_const c = tconst_prefix ^ lookup_const c
+
+fun make_type_class clas = class_prefix ^ ascii_of clas;
+
+
+(**** name pool ****)
+ 
+type name = string * string
+type name_pool = string Symtab.table * string Symtab.table
+
+fun empty_name_pool readable_names =
+  if readable_names then SOME (`I Symtab.empty) else NONE
+
+fun pool_fold f xs z = pair z #> fold_rev (fn x => uncurry (f x)) xs
+fun pool_map f xs =
+  pool_fold (fn x => fn ys => fn pool => f x pool |>> (fn y => y :: ys)) xs []
+
+fun add_nice_name full_name nice_prefix j the_pool =
+  let
+    val nice_name = nice_prefix ^ (if j = 0 then "" else "_" ^ Int.toString j)
+  in
+    case Symtab.lookup (snd the_pool) nice_name of
+      SOME full_name' =>
+      if full_name = full_name' then (nice_name, the_pool)
+      else add_nice_name full_name nice_prefix (j + 1) the_pool
+    | NONE =>
+      (nice_name, (Symtab.update_new (full_name, nice_name) (fst the_pool),
+                   Symtab.update_new (nice_name, full_name) (snd the_pool)))
+  end
+
+fun translate_first_char f s =
+  String.str (f (String.sub (s, 0))) ^ String.extract (s, 1, NONE)
+
+fun readable_name full_name s =
+  let
+    val s = s |> Long_Name.base_name |> Name.desymbolize false
+    val s' = s |> explode |> rev |> dropwhile (curry (op =) "'")
+    val s' =
+      (s' |> rev
+          |> implode
+          |> String.translate
+                 (fn c => if Char.isAlphaNum c orelse c = #"_" then String.str c
+                          else ""))
+      ^ replicate_string (String.size s - length s') "_"
+    val s' =
+      if s' = "" orelse not (Char.isAlpha (String.sub (s', 0))) then "X" ^ s'
+      else s'
+    (* Avoid "equal", since it's built into ATPs; and "op" is very ambiguous
+       ("op &", "op |", etc.). *)
+    val s' = if s' = "equal" orelse s' = "op" then full_name else s'
+  in
+    case (Char.isLower (String.sub (full_name, 0)),
+          Char.isLower (String.sub (s', 0))) of
+      (true, false) => translate_first_char Char.toLower s'
+    | (false, true) => translate_first_char Char.toUpper s'
+    | _ => s'
+  end
+
+fun nice_name (full_name, _) NONE = (full_name, NONE)
+  | nice_name (full_name, desired_name) (SOME the_pool) =
+    case Symtab.lookup (fst the_pool) full_name of
+      SOME nice_name => (nice_name, SOME the_pool)
+    | NONE => add_nice_name full_name (readable_name full_name desired_name) 0
+                            the_pool
+              |> apsnd SOME
+
+(**** Definitions and functions for FOL clauses for TPTP format output ****)
+
+datatype kind = Axiom | Conjecture
+
+(**** Isabelle FOL clauses ****)
+
+(* The first component is the type class; the second is a TVar or TFree. *)
+datatype type_literal =
+  TyLitVar of string * name |
+  TyLitFree of string * name
+
+exception CLAUSE of string * term;
+
+(*Make literals for sorted type variables*)
+fun sorts_on_typs_aux (_, [])   = []
+  | sorts_on_typs_aux ((x,i),  s::ss) =
+      let val sorts = sorts_on_typs_aux ((x,i), ss)
+      in
+          if s = "HOL.type" then sorts
+          else if i = ~1 then TyLitFree (make_type_class s, `make_fixed_type_var x) :: sorts
+          else TyLitVar (make_type_class s, (make_schematic_type_var (x,i), x)) :: sorts
+      end;
+
+fun sorts_on_typs (TFree (a,s)) = sorts_on_typs_aux ((a,~1),s)
+  | sorts_on_typs (TVar (v,s))  = sorts_on_typs_aux (v,s);
+
+(*Given a list of sorted type variables, return a list of type literals.*)
+fun type_literals_for_types Ts =
+  fold (union (op =)) (map sorts_on_typs Ts) []
+
+(** make axiom and conjecture clauses. **)
+
+(**** Isabelle arities ****)
+
+datatype arLit = TConsLit of class * string * string list
+               | TVarLit of class * string;
+
+datatype arity_clause =
+  ArityClause of {axiom_name: string, conclLit: arLit, premLits: arLit list}
+
+
+fun gen_TVars 0 = []
+  | gen_TVars n = ("T_" ^ Int.toString n) :: gen_TVars (n-1);
+
+fun pack_sort(_,[])  = []
+  | pack_sort(tvar, "HOL.type"::srt) = pack_sort(tvar, srt)   (*IGNORE sort "type"*)
+  | pack_sort(tvar, cls::srt) =  (cls, tvar) :: pack_sort(tvar, srt);
+
+(*Arity of type constructor tcon :: (arg1,...,argN)res*)
+fun make_axiom_arity_clause (tcons, axiom_name, (cls,args)) =
+   let val tvars = gen_TVars (length args)
+       val tvars_srts = ListPair.zip (tvars,args)
+   in
+     ArityClause {axiom_name = axiom_name, 
+                  conclLit = TConsLit (cls, make_fixed_type_const tcons, tvars),
+                  premLits = map TVarLit (union_all(map pack_sort tvars_srts))}
+   end;
+
+
+(**** Isabelle class relations ****)
+
+datatype classrel_clause =
+  ClassrelClause of {axiom_name: string, subclass: class, superclass: class}
+
+(*Generate all pairs (sub,super) such that sub is a proper subclass of super in theory thy.*)
+fun class_pairs _ [] _ = []
+  | class_pairs thy subs supers =
+      let
+        val class_less = Sorts.class_less (Sign.classes_of thy)
+        fun add_super sub super = class_less (sub, super) ? cons (sub, super)
+        fun add_supers sub = fold (add_super sub) supers
+      in fold add_supers subs [] end
+
+fun make_classrel_clause (sub,super) =
+  ClassrelClause {axiom_name = classrel_clause_prefix ^ ascii_of sub ^ "_" ^
+                               ascii_of super,
+                  subclass = make_type_class sub,
+                  superclass = make_type_class super};
+
+fun make_classrel_clauses thy subs supers =
+  map make_classrel_clause (class_pairs thy subs supers);
+
+
+(** Isabelle arities **)
+
+fun arity_clause _ _ (_, []) = []
+  | arity_clause seen n (tcons, ("HOL.type",_)::ars) =  (*ignore*)
+      arity_clause seen n (tcons,ars)
+  | arity_clause seen n (tcons, (ar as (class,_)) :: ars) =
+      if member (op =) seen class then (*multiple arities for the same tycon, class pair*)
+          make_axiom_arity_clause (tcons, lookup_const tcons ^ "_" ^ class ^ "_" ^ Int.toString n, ar) ::
+          arity_clause seen (n+1) (tcons,ars)
+      else
+          make_axiom_arity_clause (tcons, lookup_const tcons ^ "_" ^ class, ar) ::
+          arity_clause (class::seen) n (tcons,ars)
+
+fun multi_arity_clause [] = []
+  | multi_arity_clause ((tcons, ars) :: tc_arlists) =
+      arity_clause [] 1 (tcons, ars) @ multi_arity_clause tc_arlists
+
+(*Generate all pairs (tycon,class,sorts) such that tycon belongs to class in theory thy
+  provided its arguments have the corresponding sorts.*)
+fun type_class_pairs thy tycons classes =
+  let val alg = Sign.classes_of thy
+      fun domain_sorts tycon = Sorts.mg_domain alg tycon o single
+      fun add_class tycon class =
+        cons (class, domain_sorts tycon class)
+        handle Sorts.CLASS_ERROR _ => I
+      fun try_classes tycon = (tycon, fold (add_class tycon) classes [])
+  in  map try_classes tycons  end;
+
+(*Proving one (tycon, class) membership may require proving others, so iterate.*)
+fun iter_type_class_pairs _ _ [] = ([], [])
+  | iter_type_class_pairs thy tycons classes =
+      let val cpairs = type_class_pairs thy tycons classes
+          val newclasses = union_all (union_all (union_all (map (map #2 o #2) cpairs)))
+            |> subtract (op =) classes |> subtract (op =) HOLogic.typeS
+          val (classes', cpairs') = iter_type_class_pairs thy tycons newclasses
+      in (union (op =) classes' classes, union (op =) cpairs' cpairs) end;
+
+fun make_arity_clauses thy tycons classes =
+  let val (classes', cpairs) = iter_type_class_pairs thy tycons classes
+  in  (classes', multi_arity_clause cpairs)  end;
+
+datatype combtyp =
+  TyVar of name |
+  TyFree of name |
+  TyConstr of name * combtyp list
+
+datatype combterm =
+  CombConst of name * combtyp * combtyp list (* Const and Free *) |
+  CombVar of name * combtyp |
+  CombApp of combterm * combterm
+
+datatype literal = Literal of bool * combterm
+
+datatype hol_clause =
+  HOLClause of {clause_id: int, axiom_name: string, th: thm, kind: kind,
+                literals: literal list, ctypes_sorts: typ list}
+
+(*********************************************************************)
+(* convert a clause with type Term.term to a clause with type clause *)
+(*********************************************************************)
+
+(*Result of a function type; no need to check that the argument type matches.*)
+fun result_type (TyConstr (_, [_, tp2])) = tp2
+  | result_type _ = raise Fail "non-function type"
+
+fun type_of_combterm (CombConst (_, tp, _)) = tp
+  | type_of_combterm (CombVar (_, tp)) = tp
+  | type_of_combterm (CombApp (t1, _)) = result_type (type_of_combterm t1)
+
+(*gets the head of a combinator application, along with the list of arguments*)
+fun strip_combterm_comb u =
+    let fun stripc (CombApp(t,u), ts) = stripc (t, u::ts)
+        |   stripc  x =  x
+    in stripc(u,[]) end
+
+fun isFalse (Literal (pol, CombConst ((c, _), _, _))) =
+      (pol andalso c = "c_False") orelse (not pol andalso c = "c_True")
+  | isFalse _ = false;
+
+fun isTrue (Literal (pol, CombConst ((c, _), _, _))) =
+      (pol andalso c = "c_True") orelse
+      (not pol andalso c = "c_False")
+  | isTrue _ = false;
+
+fun isTaut (HOLClause {literals,...}) = exists isTrue literals;
+
+fun type_of (Type (a, Ts)) =
+    let val (folTypes,ts) = types_of Ts in
+      (TyConstr (`make_fixed_type_const a, folTypes), ts)
+    end
+  | type_of (tp as TFree (a, _)) = (TyFree (`make_fixed_type_var a), [tp])
+  | type_of (tp as TVar (x, _)) =
+    (TyVar (make_schematic_type_var x, string_of_indexname x), [tp])
+and types_of Ts =
+    let val (folTyps, ts) = ListPair.unzip (map type_of Ts) in
+      (folTyps, union_all ts)
+    end
+
+(* same as above, but no gathering of sort information *)
+fun simp_type_of (Type (a, Ts)) =
+      TyConstr (`make_fixed_type_const a, map simp_type_of Ts)
+  | simp_type_of (TFree (a, _)) = TyFree (`make_fixed_type_var a)
+  | simp_type_of (TVar (x, _)) =
+    TyVar (make_schematic_type_var x, string_of_indexname x)
+
+(* convert a Term.term (with combinators) into a combterm, also accummulate sort info *)
+fun combterm_of thy (Const (c, T)) =
+      let
+        val (tp, ts) = type_of T
+        val tvar_list =
+          (if String.isPrefix skolem_theory_name c then
+             [] |> Term.add_tvarsT T |> map TVar
+           else
+             (c, T) |> Sign.const_typargs thy)
+          |> map simp_type_of
+        val c' = CombConst (`make_fixed_const c, tp, tvar_list)
+      in  (c',ts)  end
+  | combterm_of _ (Free(v, T)) =
+      let val (tp,ts) = type_of T
+          val v' = CombConst (`make_fixed_var v, tp, [])
+      in  (v',ts)  end
+  | combterm_of _ (Var(v, T)) =
+      let val (tp,ts) = type_of T
+          val v' = CombVar ((make_schematic_var v, string_of_indexname v), tp)
+      in  (v',ts)  end
+  | combterm_of thy (P $ Q) =
+      let val (P', tsP) = combterm_of thy P
+          val (Q', tsQ) = combterm_of thy Q
+      in  (CombApp (P', Q'), union (op =) tsP tsQ)  end
+  | combterm_of _ (t as Abs _) = raise Fail "HOL clause: Abs"
+
+fun predicate_of thy ((@{const Not} $ P), pos) = predicate_of thy (P, not pos)
+  | predicate_of thy (t, pos) = (combterm_of thy (Envir.eta_contract t), pos)
+
+fun literals_of_term1 args thy (@{const Trueprop} $ P) =
+    literals_of_term1 args thy P
+  | literals_of_term1 args thy (@{const "op |"} $ P $ Q) =
+    literals_of_term1 (literals_of_term1 args thy P) thy Q
+  | literals_of_term1 (lits, ts) thy P =
+    let val ((pred, ts'), pol) = predicate_of thy (P, true) in
+      (Literal (pol, pred) :: lits, union (op =) ts ts')
+    end
+val literals_of_term = literals_of_term1 ([], [])
+
+fun skolem_name i j num_T_args =
+  skolem_prefix ^ (space_implode "_" (map Int.toString [i, j, num_T_args])) ^
+  skolem_infix ^ "g"
+
+fun conceal_skolem_somes i skolem_somes t =
+  if exists_Const (curry (op =) @{const_name skolem_id} o fst) t then
+    let
+      fun aux skolem_somes
+              (t as (Const (@{const_name skolem_id}, Type (_, [_, T])) $ _)) =
+          let
+            val (skolem_somes, s) =
+              if i = ~1 then
+                (skolem_somes, @{const_name undefined})
+              else case AList.find (op aconv) skolem_somes t of
+                s :: _ => (skolem_somes, s)
+              | [] =>
+                let
+                  val s = skolem_theory_name ^ "." ^
+                          skolem_name i (length skolem_somes)
+                                        (length (Term.add_tvarsT T []))
+                in ((s, t) :: skolem_somes, s) end
+          in (skolem_somes, Const (s, T)) end
+        | aux skolem_somes (t1 $ t2) =
+          let
+            val (skolem_somes, t1) = aux skolem_somes t1
+            val (skolem_somes, t2) = aux skolem_somes t2
+          in (skolem_somes, t1 $ t2) end
+        | aux skolem_somes (Abs (s, T, t')) =
+          let val (skolem_somes, t') = aux skolem_somes t' in
+            (skolem_somes, Abs (s, T, t'))
+          end
+        | aux skolem_somes t = (skolem_somes, t)
+    in aux skolem_somes t end
+  else
+    (skolem_somes, t)
+
+fun is_quasi_fol_theorem thy =
+  Meson.is_fol_term thy o snd o conceal_skolem_somes ~1 [] o prop_of
+
+(* Trivial problem, which resolution cannot handle (empty clause) *)
+exception TRIVIAL of unit
+
+(* making axiom and conjecture clauses *)
+fun make_clause thy (clause_id, axiom_name, kind, th) skolem_somes =
+  let
+    val (skolem_somes, t) =
+      th |> prop_of |> conceal_skolem_somes clause_id skolem_somes
+    val (lits, ctypes_sorts) = literals_of_term thy t
+  in
+    if forall isFalse lits then
+      raise TRIVIAL ()
+    else
+      (skolem_somes,
+       HOLClause {clause_id = clause_id, axiom_name = axiom_name, th = th,
+                  kind = kind, literals = lits, ctypes_sorts = ctypes_sorts})
+  end
+
+fun add_axiom_clause thy (th, ((name, id), _ : thm)) (skolem_somes, clss) =
+  let
+    val (skolem_somes, cls) = make_clause thy (id, name, Axiom, th) skolem_somes
+  in (skolem_somes, clss |> not (isTaut cls) ? cons (name, cls)) end
+
+fun make_axiom_clauses thy clauses =
+  ([], []) |> fold_rev (add_axiom_clause thy) clauses |> snd
+
+fun make_conjecture_clauses thy =
+  let
+    fun aux _ _ [] = []
+      | aux n skolem_somes (th :: ths) =
+        let
+          val (skolem_somes, cls) =
+            make_clause thy (n, "conjecture", Conjecture, th) skolem_somes
+        in cls :: aux (n + 1) skolem_somes ths end
+  in aux 0 [] end
+
+(** Helper clauses **)
+
+fun count_combterm (CombConst ((c, _), _, _)) =
+    Symtab.map_entry c (Integer.add 1)
+  | count_combterm (CombVar _) = I
+  | count_combterm (CombApp (t1, t2)) = count_combterm t1 #> count_combterm t2
+fun count_literal (Literal (_, t)) = count_combterm t
+fun count_clause (HOLClause {literals, ...}) = fold count_literal literals
+
+fun raw_cnf_rules_pairs ps = map (fn (name, thm) => (thm, ((name, 0), thm))) ps
+fun cnf_helper_thms thy raw =
+  map (`Thm.get_name_hint)
+  #> (if raw then raw_cnf_rules_pairs else cnf_rules_pairs thy)
+
+val optional_helpers =
+  [(["c_COMBI", "c_COMBK"], (false, @{thms COMBI_def COMBK_def})),
+   (["c_COMBB", "c_COMBC"], (false, @{thms COMBB_def COMBC_def})),
+   (["c_COMBS"], (false, @{thms COMBS_def}))]
+val optional_typed_helpers =
+  [(["c_True", "c_False"], (true, @{thms True_or_False})),
+   (["c_If"], (true, @{thms if_True if_False True_or_False}))]
+val mandatory_helpers = @{thms fequal_imp_equal equal_imp_fequal}
+
+val init_counters =
+  Symtab.make (maps (maps (map (rpair 0) o fst))
+                    [optional_helpers, optional_typed_helpers])
+
+fun get_helper_clauses thy is_FO full_types conjectures axcls =
+  let
+    val axclauses = map snd (make_axiom_clauses thy axcls)
+    val ct = fold (fold count_clause) [conjectures, axclauses] init_counters
+    fun is_needed c = the (Symtab.lookup ct c) > 0
+    val cnfs =
+      (optional_helpers
+       |> full_types ? append optional_typed_helpers
+       |> maps (fn (ss, (raw, ths)) =>
+                   if exists is_needed ss then cnf_helper_thms thy raw ths
+                   else []))
+      @ (if is_FO then [] else cnf_helper_thms thy false mandatory_helpers)
+  in map snd (make_axiom_clauses thy cnfs) end
+
+fun make_clause_table xs =
+  fold (Termtab.update o `(prop_of o fst)) xs Termtab.empty
+
+
+(***************************************************************)
+(* Type Classes Present in the Axiom or Conjecture Clauses     *)
+(***************************************************************)
+
+fun set_insert (x, s) = Symtab.update (x, ()) s
+
+fun add_classes (sorts, cset) = List.foldl set_insert cset (flat sorts)
+
+(*Remove this trivial type class*)
+fun delete_type cset = Symtab.delete_safe (the_single @{sort HOL.type}) cset;
+
+fun tfree_classes_of_terms ts =
+  let val sorts_list = map (map #2 o OldTerm.term_tfrees) ts
+  in  Symtab.keys (delete_type (List.foldl add_classes Symtab.empty sorts_list))  end;
+
+fun tvar_classes_of_terms ts =
+  let val sorts_list = map (map #2 o OldTerm.term_tvars) ts
+  in  Symtab.keys (delete_type (List.foldl add_classes Symtab.empty sorts_list))  end;
+
+(*fold type constructors*)
+fun fold_type_consts f (Type (a, Ts)) x = fold (fold_type_consts f) Ts (f (a,x))
+  | fold_type_consts _ _ x = x;
+
+(*Type constructors used to instantiate overloaded constants are the only ones needed.*)
+fun add_type_consts_in_term thy =
+  let
+    val const_typargs = Sign.const_typargs thy
+    fun aux (Const x) = fold (fold_type_consts set_insert) (const_typargs x)
+      | aux (Abs (_, _, u)) = aux u
+      | aux (Const (@{const_name skolem_id}, _) $ _) = I
+      | aux (t $ u) = aux t #> aux u
+      | aux _ = I
+  in aux end
+
+fun type_consts_of_terms thy ts =
+  Symtab.keys (fold (add_type_consts_in_term thy) ts Symtab.empty);
+
+(* Remove existing axiom clauses from the conjecture clauses, as this can
+   dramatically boost an ATP's performance (for some reason). *)
+fun subtract_cls ax_clauses =
+  filter_out (Termtab.defined (make_clause_table ax_clauses) o prop_of)
+
+(* prepare for passing to writer,
+   create additional clauses based on the information from extra_cls *)
+fun prepare_clauses full_types goal_cls axcls extra_cls thy =
+  let
+    val is_FO = forall (Meson.is_fol_term thy o prop_of) goal_cls
+    val ccls = subtract_cls extra_cls goal_cls
+    val _ = app (fn th => trace_msg (fn _ => Display.string_of_thm_global thy th)) ccls
+    val ccltms = map prop_of ccls
+    and axtms = map (prop_of o #1) extra_cls
+    val subs = tfree_classes_of_terms ccltms
+    and supers = tvar_classes_of_terms axtms
+    and tycons = type_consts_of_terms thy (ccltms @ axtms)
+    (*TFrees in conjecture clauses; TVars in axiom clauses*)
+    val conjectures = make_conjecture_clauses thy ccls
+    val (_, extra_clauses) = ListPair.unzip (make_axiom_clauses thy extra_cls)
+    val (clnames, axiom_clauses) = ListPair.unzip (make_axiom_clauses thy axcls)
+    val helper_clauses =
+      get_helper_clauses thy is_FO full_types conjectures extra_cls
+    val (supers', arity_clauses) = make_arity_clauses thy tycons supers
+    val classrel_clauses = make_classrel_clauses thy subs supers'
+  in
+    (Vector.fromList clnames,
+      (conjectures, axiom_clauses, extra_clauses, helper_clauses, classrel_clauses, arity_clauses))
+  end
+
+end;