src/HOL/Tools/Sledgehammer/sledgehammer_hol_clause.ML

added options to Sledgehammer;
syntax: sledgehammer [options] goal_no, where "[options]" and "goal_no" are optional

(*  Title:      HOL/Sledgehammer/sledgehammer_hol_clause.ML
    Author:     Jia Meng, NICTA

FOL clauses translated from HOL formulae.
*)

signature SLEDGEHAMMER_HOL_CLAUSE =
sig
  type kind = Sledgehammer_FOL_Clause.kind
  type fol_type = Sledgehammer_FOL_Clause.fol_type
  type classrel_clause = Sledgehammer_FOL_Clause.classrel_clause
  type arity_clause = Sledgehammer_FOL_Clause.arity_clause
  type axiom_name = string
  type polarity = bool
  type hol_clause_id = int

  datatype combterm =
    CombConst of string * fol_type * fol_type list (* Const and Free *) |
    CombVar of string * fol_type |
    CombApp of combterm * combterm
  datatype literal = Literal of polarity * combterm
  datatype hol_clause =
    HOLClause of {clause_id: hol_clause_id, axiom_name: axiom_name, th: thm,
                  kind: kind, literals: literal list, ctypes_sorts: typ list}

  val type_of_combterm : combterm -> fol_type
  val strip_combterm_comb : combterm -> combterm * combterm list
  val literals_of_term : theory -> term -> literal list * typ list
  exception TRIVIAL
  val make_conjecture_clauses : bool -> theory -> thm list -> hol_clause list
  val make_axiom_clauses : bool -> theory ->
       (thm * (axiom_name * hol_clause_id)) list -> (axiom_name * hol_clause) list
  val get_helper_clauses : bool -> theory -> bool ->
       hol_clause list * (thm * (axiom_name * hol_clause_id)) list * string list ->
       hol_clause list
  val write_tptp_file : bool -> Path.T ->
    hol_clause list * hol_clause list * hol_clause list * hol_clause list *
    classrel_clause list * arity_clause list ->
    int * int
  val write_dfg_file : bool -> Path.T ->
    hol_clause list * hol_clause list * hol_clause list * hol_clause list *
    classrel_clause list * arity_clause list -> int * int
end

structure Sledgehammer_HOL_Clause : SLEDGEHAMMER_HOL_CLAUSE =
struct

open Sledgehammer_FOL_Clause
open Sledgehammer_Fact_Preprocessor

(* Parameter "full_types" below indicates that full type information is to be
exported *)

(* If true, each function will be directly applied to as many arguments as
   possible, avoiding use of the "apply" operator. Use of hBOOL is also
   minimized. *)
val minimize_applies = true;

fun min_arity_of const_min_arity c = the_default 0 (Symtab.lookup const_min_arity c);

(*True if the constant ever appears outside of the top-level position in literals.
  If false, the constant always receives all of its arguments and is used as a predicate.*)
fun needs_hBOOL const_needs_hBOOL c =
  not minimize_applies orelse
    the_default false (Symtab.lookup const_needs_hBOOL c);


(******************************************************)
(* data types for typed combinator expressions        *)
(******************************************************)

type axiom_name = string;
type polarity = bool;
type hol_clause_id = int;

datatype combterm =
  CombConst of string * fol_type * fol_type list (* Const and Free *) |
  CombVar of string * fol_type |
  CombApp of combterm * combterm

datatype literal = Literal of polarity * combterm;

datatype hol_clause =
  HOLClause of {clause_id: hol_clause_id, axiom_name: axiom_name, th: thm,
                kind: kind, literals: literal list, ctypes_sorts: typ list};


(*********************************************************************)
(* convert a clause with type Term.term to a clause with type clause *)
(*********************************************************************)

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 dfg (Type (a, Ts)) =
      let val (folTypes,ts) = types_of dfg Ts
      in  (Comp(make_fixed_type_const dfg a, folTypes), ts)  end
  | type_of _ (tp as TFree (a, _)) = (AtomF (make_fixed_type_var a), [tp])
  | type_of _ (tp as TVar (v, _)) = (AtomV (make_schematic_type_var v), [tp])
and types_of dfg Ts =
      let val (folTyps,ts) = ListPair.unzip (map (type_of dfg) Ts)
      in  (folTyps, union_all ts)  end;

(* same as above, but no gathering of sort information *)
fun simp_type_of dfg (Type (a, Ts)) =
      Comp(make_fixed_type_const dfg a, map (simp_type_of dfg) Ts)
  | simp_type_of _ (TFree (a, _)) = AtomF (make_fixed_type_var a)
  | simp_type_of _ (TVar (v, _)) = AtomV (make_schematic_type_var v);


fun const_type_of dfg thy (c,t) =
      let val (tp,ts) = type_of dfg t
      in  (tp, ts, map (simp_type_of dfg) (Sign.const_typargs thy (c,t))) end;

(* convert a Term.term (with combinators) into a combterm, also accummulate sort info *)
fun combterm_of dfg thy (Const(c,t)) =
      let val (tp,ts,tvar_list) = const_type_of dfg thy (c,t)
          val c' = CombConst(make_fixed_const dfg c, tp, tvar_list)
      in  (c',ts)  end
  | combterm_of dfg _ (Free(v,t)) =
      let val (tp,ts) = type_of dfg t
          val v' = CombConst(make_fixed_var v, tp, [])
      in  (v',ts)  end
  | combterm_of dfg _ (Var(v,t)) =
      let val (tp,ts) = type_of dfg t
          val v' = CombVar(make_schematic_var v,tp)
      in  (v',ts)  end
  | combterm_of dfg thy (P $ Q) =
      let val (P',tsP) = combterm_of dfg thy P
          val (Q',tsQ) = combterm_of dfg thy Q
      in  (CombApp(P',Q'), union (op =) tsP tsQ)  end
  | combterm_of _ _ (t as Abs _) = raise CLAUSE ("HOL CLAUSE", t);

fun predicate_of dfg thy ((@{const Not} $ P), polarity) = predicate_of dfg thy (P, not polarity)
  | predicate_of dfg thy (t,polarity) = (combterm_of dfg thy (Envir.eta_contract t), polarity);

fun literals_of_term1 dfg thy args (@{const Trueprop} $ P) = literals_of_term1 dfg thy args P
  | literals_of_term1 dfg thy args (@{const "op |"} $ P $ Q) =
      literals_of_term1 dfg thy (literals_of_term1 dfg thy args P) Q
  | literals_of_term1 dfg thy (lits,ts) P =
      let val ((pred,ts'),pol) = predicate_of dfg thy (P,true)
      in
          (Literal(pol,pred)::lits, union (op =) ts ts')
      end;

fun literals_of_term_dfg dfg thy P = literals_of_term1 dfg thy ([],[]) P;
val literals_of_term = literals_of_term_dfg false;

(* Trivial problem, which resolution cannot handle (empty clause) *)
exception TRIVIAL;

(* making axiom and conjecture clauses *)
fun make_clause dfg thy (clause_id, axiom_name, kind, th) =
    let val (lits,ctypes_sorts) = literals_of_term_dfg dfg thy (prop_of th)
    in
        if forall isFalse lits then
            raise TRIVIAL
        else
            HOLClause {clause_id = clause_id, axiom_name = axiom_name, th = th,
                       kind = kind, literals = lits, ctypes_sorts = ctypes_sorts}
    end;


fun add_axiom_clause dfg thy ((th,(name,id)), pairs) =
  let val cls = make_clause dfg thy (id, name, Axiom, th)
  in
      if isTaut cls then pairs else (name,cls)::pairs
  end;

fun make_axiom_clauses dfg thy = List.foldl (add_axiom_clause dfg thy) [];

fun make_conjecture_clauses_aux _ _ _ [] = []
  | make_conjecture_clauses_aux dfg thy n (th::ths) =
      make_clause dfg thy (n,"conjecture", Conjecture, th) ::
      make_conjecture_clauses_aux dfg thy (n+1) ths;

fun make_conjecture_clauses dfg thy = make_conjecture_clauses_aux dfg thy 0;


(**********************************************************************)
(* convert clause into ATP specific formats:                          *)
(* TPTP used by Vampire and E                                         *)
(* DFG used by SPASS                                                  *)
(**********************************************************************)

(*Result of a function type; no need to check that the argument type matches.*)
fun result_type (Comp ("tc_fun", [_, tp2])) = tp2
  | result_type _ = error "result_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;

val type_wrapper = "ti";

fun head_needs_hBOOL const_needs_hBOOL (CombConst(c,_,_)) = needs_hBOOL const_needs_hBOOL c
  | head_needs_hBOOL _ _ = true;

fun wrap_type full_types (s, tp) =
  if full_types then type_wrapper ^ paren_pack [s, string_of_fol_type tp] else s;

fun apply ss = "hAPP" ^ paren_pack ss;

fun rev_apply (v, []) = v
  | rev_apply (v, arg::args) = apply [rev_apply (v, args), arg];

fun string_apply (v, args) = rev_apply (v, rev args);

(*Apply an operator to the argument strings, using either the "apply" operator or
  direct function application.*)
fun string_of_applic full_types cma (CombConst (c, _, tvars), args) =
      let val c = if c = "equal" then "c_fequal" else c
          val nargs = min_arity_of cma c
          val args1 = List.take(args, nargs)
            handle Subscript => error ("string_of_applic: " ^ c ^ " has arity " ^
                                         Int.toString nargs ^ " but is applied to " ^
                                         space_implode ", " args)
          val args2 = List.drop(args, nargs)
          val targs = if full_types then [] else map string_of_fol_type tvars
      in
          string_apply (c ^ paren_pack (args1@targs), args2)
      end
  | string_of_applic _ _ (CombVar (v, _), args) = string_apply (v, args)
  | string_of_applic _ _ _ = error "string_of_applic";

fun wrap_type_if full_types cnh (head, s, tp) =
  if head_needs_hBOOL cnh head then wrap_type full_types (s, tp) else s;

fun string_of_combterm (params as (full_types, cma, cnh)) t =
  let val (head, args) = strip_combterm_comb t
  in  wrap_type_if full_types cnh (head,
          string_of_applic full_types cma
                           (head, map (string_of_combterm (params)) args),
          type_of_combterm t)
  end;

(*Boolean-valued terms are here converted to literals.*)
fun boolify params t =
  "hBOOL" ^ paren_pack [string_of_combterm params t];

fun string_of_predicate (params as (_,_,cnh)) t =
  case t of
      (CombApp(CombApp(CombConst("equal",_,_), t1), t2)) =>
          (*DFG only: new TPTP prefers infix equality*)
          ("equal" ^ paren_pack [string_of_combterm params t1, string_of_combterm params t2])
    | _ =>
          case #1 (strip_combterm_comb t) of
              CombConst(c,_,_) => if needs_hBOOL cnh c then boolify params t else string_of_combterm params t
            | _ => boolify params t;


(*** tptp format ***)

fun tptp_of_equality params pol (t1,t2) =
  let val eqop = if pol then " = " else " != "
  in  string_of_combterm params t1 ^ eqop ^ string_of_combterm params t2  end;

fun tptp_literal params (Literal(pol, CombApp(CombApp(CombConst("equal", _, _), t1), t2))) =
      tptp_of_equality params pol (t1,t2)
  | tptp_literal params (Literal(pol,pred)) =
      tptp_sign pol (string_of_predicate params pred);

(*Given a clause, returns its literals paired with a list of literals concerning TFrees;
  the latter should only occur in conjecture clauses.*)
fun tptp_type_lits params pos (HOLClause {literals, ctypes_sorts, ...}) =
      (map (tptp_literal params) literals, 
       map (tptp_of_typeLit pos) (add_typs ctypes_sorts));

fun clause2tptp params (cls as HOLClause {axiom_name, clause_id, kind, ...}) =
  let val (lits,tylits) = tptp_type_lits params (kind = Conjecture) cls
  in
      (gen_tptp_cls (clause_id, axiom_name, kind, lits, tylits), tylits)
  end;


(*** dfg format ***)

fun dfg_literal params (Literal(pol,pred)) = dfg_sign pol (string_of_predicate params pred);

fun dfg_type_lits params pos (HOLClause {literals, ctypes_sorts, ...}) =
      (map (dfg_literal params) literals, 
       map (dfg_of_typeLit pos) (add_typs ctypes_sorts));

fun get_uvars (CombConst _) vars = vars
  | get_uvars (CombVar(v,_)) vars = (v::vars)
  | get_uvars (CombApp(P,Q)) vars = get_uvars P (get_uvars Q vars);

fun get_uvars_l (Literal(_,c)) = get_uvars c [];

fun dfg_vars (HOLClause {literals,...}) = union_all (map get_uvars_l literals);

fun clause2dfg params (cls as HOLClause {axiom_name, clause_id, kind,
                                         ctypes_sorts, ...}) =
  let val (lits,tylits) = dfg_type_lits params (kind = Conjecture) cls
      val vars = dfg_vars cls
      val tvars = get_tvar_strs ctypes_sorts
  in
      (gen_dfg_cls (clause_id, axiom_name, kind, lits, tylits, tvars@vars), tylits)
  end;


(** For DFG format: accumulate function and predicate declarations **)

fun addtypes tvars tab = List.foldl add_foltype_funcs tab tvars;

fun add_decls (full_types, cma, cnh) (CombConst (c, _, tvars), (funcs, preds)) =
      if c = "equal" then (addtypes tvars funcs, preds)
      else
        let val arity = min_arity_of cma c
            val ntys = if not full_types then length tvars else 0
            val addit = Symtab.update(c, arity+ntys)
        in
            if needs_hBOOL cnh c then (addtypes tvars (addit funcs), preds)
            else (addtypes tvars funcs, addit preds)
        end
  | add_decls _ (CombVar(_,ctp), (funcs,preds)) =
      (add_foltype_funcs (ctp,funcs), preds)
  | add_decls params (CombApp(P,Q),decls) = add_decls params (P,add_decls params (Q,decls));

fun add_literal_decls params (Literal (_,c), decls) = add_decls params (c,decls);

fun add_clause_decls params (HOLClause {literals, ...}, decls) =
    List.foldl (add_literal_decls params) decls literals
    handle Symtab.DUP a => error ("function " ^ a ^ " has multiple arities")

fun decls_of_clauses params clauses arity_clauses =
  let val init_functab = Symtab.update (type_wrapper,2) (Symtab.update ("hAPP",2) init_functab)
      val init_predtab = Symtab.update ("hBOOL",1) Symtab.empty
      val (functab,predtab) = (List.foldl (add_clause_decls params) (init_functab, init_predtab) clauses)
  in
      (Symtab.dest (List.foldl add_arity_clause_funcs functab arity_clauses),
       Symtab.dest predtab)
  end;

fun add_clause_preds (HOLClause {ctypes_sorts, ...}, preds) =
  List.foldl add_type_sort_preds preds ctypes_sorts
  handle Symtab.DUP a => error ("predicate " ^ a ^ " has multiple arities")

(*Higher-order clauses have only the predicates hBOOL and type classes.*)
fun preds_of_clauses clauses clsrel_clauses arity_clauses =
    Symtab.dest
        (List.foldl add_classrel_clause_preds
               (List.foldl add_arity_clause_preds
                      (List.foldl add_clause_preds Symtab.empty clauses)
                      arity_clauses)
               clsrel_clauses)


(**********************************************************************)
(* write clauses to files                                             *)
(**********************************************************************)

val init_counters =
  Symtab.make [("c_COMBI", 0), ("c_COMBK", 0), ("c_COMBB", 0), ("c_COMBC", 0),
               ("c_COMBS", 0)];

fun count_combterm (CombConst (c, _, _), ct) =
     (case Symtab.lookup ct c of NONE => ct  (*no counter*)
                               | SOME n => Symtab.update (c,n+1) ct)
  | count_combterm (CombVar _, ct) = ct
  | count_combterm (CombApp(t1,t2), ct) = count_combterm(t1, count_combterm(t2, ct));

fun count_literal (Literal(_,t), ct) = count_combterm(t,ct);

fun count_clause (HOLClause {literals, ...}, ct) =
  List.foldl count_literal ct literals;

fun count_user_clause user_lemmas (HOLClause {axiom_name, literals, ...}, ct) =
  if axiom_name mem_string user_lemmas then List.foldl count_literal ct literals
  else ct;

fun cnf_helper_thms thy = cnf_rules_pairs thy o map pairname

fun get_helper_clauses dfg thy isFO (conjectures, axcls, user_lemmas) =
  if isFO then
    []
  else
    let
        val axclauses = map #2 (make_axiom_clauses dfg thy axcls)
        val ct0 = List.foldl count_clause init_counters conjectures
        val ct = List.foldl (count_user_clause user_lemmas) ct0 axclauses
        fun needed c = the (Symtab.lookup ct c) > 0
        val IK = if needed "c_COMBI" orelse needed "c_COMBK"
                 then cnf_helper_thms thy [@{thm COMBI_def}, @{thm COMBK_def}]
                 else []
        val BC = if needed "c_COMBB" orelse needed "c_COMBC"
                 then cnf_helper_thms thy [@{thm COMBB_def}, @{thm COMBC_def}]
                 else []
        val S = if needed "c_COMBS" then cnf_helper_thms thy [@{thm COMBS_def}]
                else []
        val other = cnf_helper_thms thy [@{thm fequal_imp_equal},
                                         @{thm equal_imp_fequal}]
    in
        map #2 (make_axiom_clauses dfg thy (other @ IK @ BC @ S))
    end;

(*Find the minimal arity of each function mentioned in the term. Also, note which uses
  are not at top level, to see if hBOOL is needed.*)
fun count_constants_term toplev t (const_min_arity, const_needs_hBOOL) =
  let val (head, args) = strip_combterm_comb t
      val n = length args
      val (const_min_arity, const_needs_hBOOL) = fold (count_constants_term false) args (const_min_arity, const_needs_hBOOL)
  in
      case head of
          CombConst (a,_,_) => (*predicate or function version of "equal"?*)
            let val a = if a="equal" andalso not toplev then "c_fequal" else a
            val const_min_arity = Symtab.map_default (a, n) (Integer.min n) const_min_arity
            in
              if toplev then (const_min_arity, const_needs_hBOOL)
              else (const_min_arity, Symtab.update (a,true) (const_needs_hBOOL))
            end
        | _ => (const_min_arity, const_needs_hBOOL)
  end;

(*A literal is a top-level term*)
fun count_constants_lit (Literal (_,t)) (const_min_arity, const_needs_hBOOL) =
  count_constants_term true t (const_min_arity, const_needs_hBOOL);

fun count_constants_clause (HOLClause {literals, ...})
                           (const_min_arity, const_needs_hBOOL) =
  fold count_constants_lit literals (const_min_arity, const_needs_hBOOL);

fun display_arity const_needs_hBOOL (c,n) =
  trace_msg (fn () => "Constant: " ^ c ^
                " arity:\t" ^ Int.toString n ^
                (if needs_hBOOL const_needs_hBOOL c then " needs hBOOL" else ""));

fun count_constants (conjectures, _, extra_clauses, helper_clauses, _, _) =
  if minimize_applies then
     let val (const_min_arity, const_needs_hBOOL) =
          fold count_constants_clause conjectures (Symtab.empty, Symtab.empty)
       |> fold count_constants_clause extra_clauses
       |> fold count_constants_clause helper_clauses
     val _ = List.app (display_arity const_needs_hBOOL) (Symtab.dest (const_min_arity))
     in (const_min_arity, const_needs_hBOOL) end
  else (Symtab.empty, Symtab.empty);

(* TPTP format *)

fun write_tptp_file full_types file clauses =
  let
    val (conjectures, axclauses, _, helper_clauses,
      classrel_clauses, arity_clauses) = clauses
    val (cma, cnh) = count_constants clauses
    val params = (full_types, cma, cnh)
    val (tptp_clss,tfree_litss) = ListPair.unzip (map (clause2tptp params) conjectures)
    val tfree_clss = map tptp_tfree_clause (List.foldl (uncurry (union (op =))) [] tfree_litss)
    val _ =
      File.write_list file (
        map (#1 o (clause2tptp params)) axclauses @
        tfree_clss @
        tptp_clss @
        map tptp_classrel_clause classrel_clauses @
        map tptp_arity_clause arity_clauses @
        map (#1 o (clause2tptp params)) helper_clauses)
    in (length axclauses + 1, length tfree_clss + length tptp_clss)
  end;


(* DFG format *)

fun write_dfg_file full_types file clauses =
  let
    val (conjectures, axclauses, _, helper_clauses,
      classrel_clauses, arity_clauses) = clauses
    val (cma, cnh) = count_constants clauses
    val params = (full_types, cma, cnh)
    val (dfg_clss, tfree_litss) = ListPair.unzip (map (clause2dfg params) conjectures)
    and probname = Path.implode (Path.base file)
    val axstrs = map (#1 o (clause2dfg params)) axclauses
    val tfree_clss = map dfg_tfree_clause (union_all tfree_litss)
    val helper_clauses_strs = map (#1 o (clause2dfg params)) helper_clauses
    val (funcs,cl_preds) = decls_of_clauses params (helper_clauses @ conjectures @ axclauses) arity_clauses
    and ty_preds = preds_of_clauses axclauses classrel_clauses arity_clauses
    val _ =
      File.write_list file (
        string_of_start probname ::
        string_of_descrip probname ::
        string_of_symbols (string_of_funcs funcs)
          (string_of_preds (cl_preds @ ty_preds)) ::
        "list_of_clauses(axioms,cnf).\n" ::
        axstrs @
        map dfg_classrel_clause classrel_clauses @
        map dfg_arity_clause arity_clauses @
        helper_clauses_strs @
        ["end_of_list.\n\nlist_of_clauses(conjectures,cnf).\n"] @
        tfree_clss @
        dfg_clss @
        ["end_of_list.\n\n",
        (*VarWeight=3 helps the HO problems, probably by counteracting the presence of hAPP*)
         "list_of_settings(SPASS).\n{*\nset_flag(VarWeight,3).\n*}\nend_of_list.\n\n",
         "end_problem.\n"])

    in (length axclauses + length classrel_clauses + length arity_clauses +
      length helper_clauses + 1, length tfree_clss + length dfg_clss)
  end;

end;