X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Fsuperposition.ml;h=6f1fb0f7f91a3e1395bf3dc71fa6a65cb39a3136;hb=dce1bca274f93a3bddcc0f6b04cbf126ccff42b0;hp=585fbe2371caf146bb2377e072cc75b37039addb;hpb=846c22b353bed991d0504818fa58e5ed65dec670;p=helm.git

diff --git a/helm/software/components/ng_paramodulation/superposition.ml b/helm/software/components/ng_paramodulation/superposition.ml
index 585fbe237..6f1fb0f7f 100644
--- a/helm/software/components/ng_paramodulation/superposition.ml
+++ b/helm/software/components/ng_paramodulation/superposition.ml
@@ -20,7 +20,11 @@ module Superposition (B : Orderings.Blob) =
     module Utils = FoUtils.Utils(B)
     module Pp = Pp.Pp(B)
     
-    exception Success of B.t Terms.bag * int * B.t Terms.unit_clause
+    exception Success of 
+      B.t Terms.bag 
+      * int 
+      * B.t Terms.unit_clause
+      * B.t Terms.substitution
 
     (* let debug s = prerr_endline (Lazy.force s);; *)
     let debug _ = ();; 
@@ -311,15 +315,21 @@ module Superposition (B : Orderings.Blob) =
     ;;
 
     (* move away *)
-    let is_identity_clause ~unify = function
+    let is_identity_clause = function
       | _, Terms.Equation (_,_,_,Terms.Eq), _, _ -> true
-      | _, Terms.Equation (l,r,_,_), vl, proof when unify ->
-          (try ignore(Unif.unification (* vl *) [] l r); true
-          with FoUnif.UnificationFailure _ -> false)
       | _, Terms.Equation (_,_,_,_), _, _ -> false
       | _, Terms.Predicate _, _, _ -> assert false          
     ;;
 
+    let is_identity_goal = function
+      | _, Terms.Equation (_,_,_,Terms.Eq), _, _ -> Some []
+      | _, Terms.Equation (l,r,_,_), vl, proof ->
+          (try Some (Unif.unification (* vl *) [] l r)
+           with FoUnif.UnificationFailure _ -> None)
+      | _, Terms.Equation (_,_,_,_), _, _ -> None
+      | _, Terms.Predicate _, _, _ -> assert false          
+    ;;
+
     let build_new_clause bag maxvar filter rule t subst id id2 pos dir =
       let maxvar, _vl, subst = Utils.relocate maxvar (Terms.vars_of_term
       (Subst.apply_subst subst t)) subst in
@@ -475,10 +485,10 @@ module Superposition (B : Orderings.Blob) =
     (* demodulate and check for subsumption *)
     let simplify table maxvar bag clause =
       debug (lazy "simplify...");
-      if is_identity_clause ~unify:false clause then bag,None
+      if is_identity_clause clause then bag,None
       (* else if orphan_murder bag actives clause then bag,None *)
       else let bag, clause = demodulate bag clause table in
-      if is_identity_clause ~unify:false clause then bag,None
+      if is_identity_clause clause then bag,None
       else
         match is_subsumed ~unify:false bag maxvar clause table with
           | None -> bag, Some clause
@@ -608,9 +618,9 @@ module Superposition (B : Orderings.Blob) =
         if no_demod then bag, clause else demodulate bag clause table 
       in
       if List.exists (are_alpha_eq clause) g_actives then None
-      else if (is_identity_clause ~unify:true clause)
-      then raise (Success (bag, maxvar, clause))
-      else   
+      else match (is_identity_goal clause) with
+	| Some subst -> raise (Success (bag,maxvar,clause,subst))
+	| None ->
         let (id,lit,vl,_) = clause in 
         (* this optimization makes sense only if we demodulated, since in 
 	   that case the clause should have been turned into an identity *)
@@ -627,7 +637,7 @@ module Superposition (B : Orderings.Blob) =
          | None -> Some (bag,clause)
          | Some (bag,maxvar,cl,subst) -> 
              debug (lazy "Goal subsumed");
-             raise (Success (bag,maxvar,cl))
+             raise (Success (bag,maxvar,cl,subst))
 (*
         match is_subsumed ~unify:true bag maxvar clause table with
         | None -> Some (bag, clause)