--- a/src/HOL/Tools/prop_logic.ML Wed Oct 21 16:41:22 2009 +1100
+++ b/src/HOL/Tools/prop_logic.ML Wed Oct 21 08:16:25 2009 +0200
@@ -111,8 +111,8 @@
| indices False = []
| indices (BoolVar i) = [i]
| indices (Not fm) = indices fm
- | indices (Or (fm1, fm2)) = (indices fm1) union_int (indices fm2)
- | indices (And (fm1, fm2)) = (indices fm1) union_int (indices fm2);
+ | indices (Or (fm1, fm2)) = union (op =) (indices fm1, indices fm2)
+ | indices (And (fm1, fm2)) = union (op =) (indices fm1, indices fm2);
(* ------------------------------------------------------------------------- *)
(* maxidx: computes the maximal variable index occuring in a formula of *)