+ let are_invertible maxvar varlist l r =
+ let _,_,subst = U.relocate maxvar varlist FoSubst.id_subst in
+ let l = FoSubst.apply_subst subst l in
+ try (ignore(Unif.alpha_eq l r);true) with
+ FoUnif.UnificationFailure _ -> false
+
+ let index_unit_clause maxvar t = function
+ | (_,Terms.Equation (l,_,_,Terms.Gt),_,_) as c ->
+ DT.index t l (Terms.Left2Right, c)
+ | (_,Terms.Equation (_,r,_,Terms.Lt),_,_) as c ->
+ DT.index t r (Terms.Right2Left, c)
+ | (_,Terms.Equation (l,r,_,Terms.Incomparable),vl,_) as c ->
+(* if are_invertible maxvar vl l r then
+ (prerr_endline ("Invertible " ^ (Pp.pp_foterm l) ^ "=" ^
+ (Pp.pp_foterm r));
+ DT.index t l (Terms.Left2Right, c))
+ else *)
+ DT.index
+ (DT.index t l (Terms.Left2Right, c))
+ r (Terms.Right2Left, c)
+ | (_,Terms.Equation (_,r,_,Terms.Eq),_,_) -> assert false
+ | (_,Terms.Predicate p,_,_) as c ->
+ DT.index t p (Terms.Nodir, c)
+ ;;
+
+ type active_set = B.t Terms.unit_clause list * DT.t
+