src/HOL/Tools/Metis/metis_tactics.ML

first step in sharing more code between ATP and Metis translation

(*  Title:      HOL/Tools/Metis/metis_tactics.ML
    Author:     Kong W. Susanto, Cambridge University Computer Laboratory
    Author:     Lawrence C. Paulson, Cambridge University Computer Laboratory
    Author:     Jasmin Blanchette, TU Muenchen
    Copyright   Cambridge University 2007

HOL setup for the Metis prover.
*)

signature METIS_TACTICS =
sig
  val metisN : string
  val metisF_N : string
  val metisFT_N : string
  val trace : bool Config.T
  val verbose : bool Config.T
  val type_lits : bool Config.T
  val new_skolemizer : bool Config.T
  val metis_tac : Proof.context -> thm list -> int -> tactic
  val metisF_tac : Proof.context -> thm list -> int -> tactic
  val metisFT_tac : Proof.context -> thm list -> int -> tactic
  val metisHO_tac : Proof.context -> thm list -> int -> tactic
  val setup : theory -> theory
end

structure Metis_Tactics : METIS_TACTICS =
struct

open ATP_Translate
open Metis_Translate
open Metis_Reconstruct

fun method_binding_for_mode HO = @{binding metis}
  | method_binding_for_mode FO = @{binding metisF}
  | method_binding_for_mode FT = @{binding metisFT}

val metisN = Binding.qualified_name_of (method_binding_for_mode HO)
val metisF_N = Binding.qualified_name_of (method_binding_for_mode FO)
val metisFT_N = Binding.qualified_name_of (method_binding_for_mode FT)

val type_lits = Attrib.setup_config_bool @{binding metis_type_lits} (K true)
val new_skolemizer = Attrib.setup_config_bool @{binding metis_new_skolemizer} (K false)

fun is_false t = t aconv (HOLogic.mk_Trueprop HOLogic.false_const);

fun have_common_thm ths1 ths2 =
  exists (member Thm.eq_thm ths1) (map Meson.make_meta_clause ths2)

(*Determining which axiom clauses are actually used*)
fun used_axioms axioms (th, Metis_Proof.Axiom _) = SOME (lookth axioms th)
  | used_axioms _ _ = NONE;

val clause_params =
  {ordering = Metis_KnuthBendixOrder.default,
   orderLiterals = Metis_Clause.UnsignedLiteralOrder,
   orderTerms = true}
val active_params =
  {clause = clause_params,
   prefactor = #prefactor Metis_Active.default,
   postfactor = #postfactor Metis_Active.default}
val waiting_params =
  {symbolsWeight = 1.0,
   variablesWeight = 0.0,
   literalsWeight = 0.0,
   models = []}
val resolution_params = {active = active_params, waiting = waiting_params}

(* Main function to start Metis proof and reconstruction *)
fun FOL_SOLVE (mode :: fallback_modes) ctxt cls ths0 =
  let val thy = Proof_Context.theory_of ctxt
      val type_lits = Config.get ctxt type_lits
      val new_skolemizer =
        Config.get ctxt new_skolemizer orelse null (Meson.choice_theorems thy)
      val th_cls_pairs =
        map2 (fn j => fn th =>
                (Thm.get_name_hint th,
                 Meson_Clausify.cnf_axiom ctxt new_skolemizer j th))
             (0 upto length ths0 - 1) ths0
      val thss = map (snd o snd) th_cls_pairs
      val dischargers = map (fst o snd) th_cls_pairs
      val _ = trace_msg ctxt (fn () => "FOL_SOLVE: CONJECTURE CLAUSES")
      val _ = app (fn th => trace_msg ctxt (fn () => Display.string_of_thm ctxt th)) cls
      val _ = trace_msg ctxt (fn () => "THEOREM CLAUSES")
      val _ = app (app (fn th => trace_msg ctxt (fn () => Display.string_of_thm ctxt th))) thss
      val (mode, {axioms, tfrees, old_skolems}) =
        prepare_metis_problem mode ctxt type_lits cls thss
      val _ = if null tfrees then ()
              else (trace_msg ctxt (fn () => "TFREE CLAUSES");
                    app (fn TyLitFree ((s, _), (s', _)) =>
                            trace_msg ctxt (fn () => s ^ "(" ^ s' ^ ")")) tfrees)
      val _ = trace_msg ctxt (fn () => "CLAUSES GIVEN TO METIS")
      val thms = map #1 axioms
      val _ = app (fn th => trace_msg ctxt (fn () => Metis_Thm.toString th)) thms
      val _ = trace_msg ctxt (fn () => "mode = " ^ string_of_mode mode)
      val _ = trace_msg ctxt (fn () => "START METIS PROVE PROCESS")
  in
      case filter (is_false o prop_of) cls of
          false_th::_ => [false_th RS @{thm FalseE}]
        | [] =>
      case Metis_Resolution.new resolution_params {axioms = thms, conjecture = []}
           |> Metis_Resolution.loop of
          Metis_Resolution.Contradiction mth =>
            let val _ = trace_msg ctxt (fn () => "METIS RECONSTRUCTION START: " ^
                          Metis_Thm.toString mth)
                val ctxt' = fold Variable.declare_constraints (map prop_of cls) ctxt
                             (*add constraints arising from converting goal to clause form*)
                val proof = Metis_Proof.proof mth
                val result = fold (replay_one_inference ctxt' mode old_skolems)
                                  proof axioms
                and used = map_filter (used_axioms axioms) proof
                val _ = trace_msg ctxt (fn () => "METIS COMPLETED...clauses actually used:")
                val _ = app (fn th => trace_msg ctxt (fn () => Display.string_of_thm ctxt th)) used
                val unused = th_cls_pairs |> map_filter (fn (name, (_, cls)) =>
                  if have_common_thm used cls then NONE else SOME name)
            in
                if not (null cls) andalso not (have_common_thm used cls) then
                  verbose_warning ctxt "The assumptions are inconsistent"
                else
                  ();
                if not (null unused) then
                  verbose_warning ctxt ("Unused theorems: " ^ commas_quote unused)
                else
                  ();
                case result of
                    (_,ith)::_ =>
                        (trace_msg ctxt (fn () => "Success: " ^ Display.string_of_thm ctxt ith);
                         [discharge_skolem_premises ctxt dischargers ith])
                  | _ => (trace_msg ctxt (fn () => "Metis: No result"); [])
            end
        | Metis_Resolution.Satisfiable _ =>
            (trace_msg ctxt (fn () => "Metis: No first-order proof with the lemmas supplied");
             if null fallback_modes then
               ()
             else
               raise METIS ("FOL_SOLVE",
                            "No first-order proof with the lemmas supplied");
             [])
  end
  handle METIS (loc, msg) =>
         case fallback_modes of
           [] => error ("Failed to replay Metis proof in Isabelle." ^
                        (if Config.get ctxt verbose then "\n" ^ loc ^ ": " ^ msg
                         else ""))
         | mode :: _ =>
           (verbose_warning ctxt
                ("Falling back on " ^
                 quote (Binding.qualified_name_of
                            (method_binding_for_mode mode)) ^ "...");
            FOL_SOLVE fallback_modes ctxt cls ths0)

val neg_clausify =
  single
  #> Meson.make_clauses_unsorted
  #> map Meson_Clausify.introduce_combinators_in_theorem
  #> Meson.finish_cnf

fun preskolem_tac ctxt st0 =
  (if exists (Meson.has_too_many_clauses ctxt)
             (Logic.prems_of_goal (prop_of st0) 1) then
     Simplifier.full_simp_tac (Meson_Clausify.ss_only @{thms not_all not_ex}) 1
     THEN cnf.cnfx_rewrite_tac ctxt 1
   else
     all_tac) st0

val type_has_top_sort =
  exists_subtype (fn TFree (_, []) => true | TVar (_, []) => true | _ => false)

fun generic_metis_tac modes ctxt ths i st0 =
  let
    val _ = trace_msg ctxt (fn () =>
        "Metis called with theorems " ^
        cat_lines (map (Display.string_of_thm ctxt) ths))
  in
    if exists_type type_has_top_sort (prop_of st0) then
      (verbose_warning ctxt "Proof state contains the universal sort {}";
       Seq.empty)
    else
      Meson.MESON (preskolem_tac ctxt) (maps neg_clausify)
                  (fn cls => resolve_tac (FOL_SOLVE modes ctxt cls ths) 1)
                  ctxt i st0
  end

val metis_modes = [HO, FT]
val metisF_modes = [FO, FT]
val metisFT_modes = [FT]
val metisHO_modes = [HO]

val metis_tac = generic_metis_tac metis_modes
val metisF_tac = generic_metis_tac metisF_modes
val metisFT_tac = generic_metis_tac metisFT_modes
val metisHO_tac = generic_metis_tac metisHO_modes

(* Whenever "X" has schematic type variables, we treat "using X by metis" as
   "by (metis X)", to prevent "Subgoal.FOCUS" from freezing the type variables.
   We don't do it for nonschematic facts "X" because this breaks a few proofs
   (in the rare and subtle case where a proof relied on extensionality not being
   applied) and brings few benefits. *)
val has_tvar =
  exists_type (exists_subtype (fn TVar _ => true | _ => false)) o prop_of

fun setup_method (modes as mode :: _) =
  Method.setup (method_binding_for_mode mode)
    (Attrib.thms >> (fn ths => fn ctxt =>
       METHOD (fn facts =>
                  let
                    val (schem_facts, nonschem_facts) =
                      List.partition has_tvar facts
                  in
                    HEADGOAL (Method.insert_tac nonschem_facts THEN'
                              CHANGED_PROP
                              o generic_metis_tac modes ctxt (schem_facts @ ths))
                  end)))

val setup =
  [(metis_modes, "Metis for FOL and HOL problems"),
   (metisF_modes, "Metis for FOL problems"),
   (metisFT_modes, "Metis for FOL/HOL problems with fully-typed translation")]
  |> fold (uncurry setup_method)

end;