X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_paramodulation%2Fterms.ml;h=87b4f383bc53bf13885069592eaf896ad9f58a0e;hb=33a4938d5ce3a5c240c0d35b6362c8072f8ba482;hp=169d19b80b68a52d0eb062162464e451a96a5757;hpb=772def9075b7b62870ebf4cecec6bcd37a549b1d;p=helm.git

diff --git a/helm/software/components/ng_paramodulation/terms.ml b/helm/software/components/ng_paramodulation/terms.ml
index 169d19b80..87b4f383b 100644
--- a/helm/software/components/ng_paramodulation/terms.ml
+++ b/helm/software/components/ng_paramodulation/terms.ml
@@ -18,7 +18,7 @@ type 'a foterm =
 
 type 'a substitution = (int * 'a foterm) list
 
-type comparison = Lt | Eq | Gt | Incomparable
+type comparison = Lt | Eq | Gt | Incomparable | Invertible
 
 type rule = Superposition | Demodulation
 type direction = Left2Right | Right2Left | Nodir
@@ -46,6 +46,19 @@ type 'a unit_clause =
 
 type 'a passive_clause = int * 'a unit_clause (* weight * equation *)
 
+let is_eq_clause (_,l,_,_) =
+  match l with
+    | Equation _ -> true
+    | Predicate _ -> false
+;;
+
+let vars_of_term t =
+  let rec aux acc = function
+    | Leaf _ -> acc
+    | Var i -> if (List.mem i acc) then acc else i::acc
+    | Node l -> List.fold_left aux acc l
+  in aux [] t
+;;
 
 module OT =
  struct
@@ -83,6 +96,7 @@ module type Blob =
     val eq : t -> t -> bool
     val compare : t -> t -> int
     val eqP : t
+    val is_eq: t foterm -> (t foterm* t foterm *t foterm) option 
     val pp : t -> string
     type input
     val embed : input -> t foterm