diff -r ff69913e2608 -r 843e0a2d44d7 Nominal/NewFv.thy
--- a/Nominal/NewFv.thy	Thu May 06 14:09:56 2010 +0200
+++ b/Nominal/NewFv.thy	Thu May 06 14:10:26 2010 +0200
@@ -140,7 +140,7 @@
   val non_rec_vars =
     case binds of
       [(SOME bn, i)] =>
-        if i mem bodys
+        if member (op =) bodys i
         then noatoms
         else ((the (AList.lookup (op=) bn_fvbn bn)) $ nth args i)
     | _ => noatoms