X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2FfoUnif.ml;h=0946873b9af5c11fea237022b2394a40393e3de6;hb=38ec119c163b0e6f97a9800933d5b71c065332e8;hp=83179b4045592ba149a849bbe0b513e61b8b963c;hpb=eca915d2656084f1e58149a476a2d305758b00f9;p=helm.git

diff --git a/helm/software/components/ng_paramodulation/foUnif.ml b/helm/software/components/ng_paramodulation/foUnif.ml
index 83179b404..0946873b9 100644
--- a/helm/software/components/ng_paramodulation/foUnif.ml
+++ b/helm/software/components/ng_paramodulation/foUnif.ml
@@ -13,11 +13,23 @@
 
 exception UnificationFailure of string Lazy.t;;
 
-module Founif (B : Terms.Blob) = struct
-  module Subst = FoSubst (*.Subst(B)*)
+let mem2 a b l =
+  let rec aux found_a found_b = function
+    | x :: tl ->
+       let found_a = found_a || x = a in
+       let found_b = found_b || x = b in
+       if found_a && found_b then true, true
+       else aux found_a found_b tl
+    | [] -> found_a, found_b
+  in
+   aux false false l
+;;
+
+module Founif (B : Orderings.Blob) = struct
+  module Subst = FoSubst 
   module U = FoUtils.Utils(B)
 
-  let unification vars locked_vars t1 t2 =
+  let unification (* vars *) locked_vars t1 t2 =
     let rec occurs_check subst what where =
       match where with
       | Terms.Var i when i = what -> true
@@ -34,24 +46,26 @@ module Founif (B : Terms.Blob) = struct
       in
       match s, t with
       | s, t when U.eq_foterm s t -> subst
-      | Terms.Var i, Terms.Var j
-          when (List.mem i locked_vars) &&(List.mem j locked_vars) ->
-          raise
-            (UnificationFailure (lazy "Inference.unification.unif"))
-      | Terms.Var i, Terms.Var j when (List.mem i locked_vars) ->
-          unif subst t s
-      | Terms.Var i, Terms.Var j when (i > j) && not (List.mem j locked_vars) ->
-          unif subst t s
+      | Terms.Var i, Terms.Var j ->
+          (* TODO: look in locked vars for both i and j at once *)
+          let i_locked, j_locked = mem2 i j locked_vars in
+          if i_locked then
+            if j_locked then
+              raise (UnificationFailure (lazy "Inference.unification.unif"))
+            else
+              Subst.build_subst j s subst
+          else
+            Subst.build_subst i t subst
       | Terms.Var i, t when occurs_check subst i t ->
-          raise
-            (UnificationFailure (lazy "Inference.unification.unif"))
+          raise (UnificationFailure (lazy "Inference.unification.unif"))
       | Terms.Var i, t when (List.mem i locked_vars) -> 
-          raise
-            (UnificationFailure (lazy "Inference.unification.unif"))
-      | Terms.Var i, t ->
-          let subst = Subst.build_subst i t subst in
-          subst
-      | _, Terms.Var _ -> unif subst t s
+          raise (UnificationFailure (lazy "Inference.unification.unif"))
+      | Terms.Var i, t -> Subst.build_subst i t subst
+      | t, Terms.Var i when occurs_check subst i t ->
+          raise (UnificationFailure (lazy "Inference.unification.unif"))
+      | t, Terms.Var i when (List.mem i locked_vars) -> 
+          raise (UnificationFailure (lazy "Inference.unification.unif"))
+      | t, Terms.Var i -> Subst.build_subst i t subst
       | Terms.Node l1, Terms.Node l2 -> (
           try
             List.fold_left2
@@ -64,34 +78,35 @@ module Founif (B : Terms.Blob) = struct
           raise (UnificationFailure (lazy "Inference.unification.unif"))
     in
     let subst = unif Subst.id_subst t1 t2 in
-    let vars = Subst.filter subst vars in
-    subst, vars
+    subst
 ;;
 
+(* Sets of variables in s and t are assumed to be disjoint  *)
   let alpha_eq s t =
     let rec equiv subst s t =
       let s = match s with Terms.Var i -> Subst.lookup i subst | _ -> s
       and t = match t with Terms.Var i -> Subst.lookup i subst | _ -> t
-	
+        
       in
       match s, t with
-	| s, t when U.eq_foterm s t -> subst
-	| Terms.Var i, Terms.Var j
-	    when (not (List.exists (fun (_,k) -> k=t) subst)) ->
+        | s, t when U.eq_foterm s t -> subst
+        | Terms.Var i, Terms.Var j
+            when (not (List.exists (fun (_,k) -> k=t) subst)) ->
             let subst = Subst.build_subst i t subst in
               subst
-	| Terms.Node l1, Terms.Node l2 -> (
+        | Terms.Node l1, Terms.Node l2 -> (
             try
               List.fold_left2
-		(fun subst' s t -> equiv subst' s t)
-		subst l1 l2
+                (fun subst' s t -> equiv subst' s t)
+                subst l1 l2
             with Invalid_argument _ ->
               raise (UnificationFailure (lazy "Inference.unification.unif"))
           )
-	| _, _ ->
+        | _, _ ->
             raise (UnificationFailure (lazy "Inference.unification.unif"))
     in
       equiv Subst.id_subst s t
 ;;
+	
 
 end