Term.invent_type_names;

--- a/src/Pure/axclass.ML	Thu Dec 13 19:05:10 2001 +0100
+++ b/src/Pure/axclass.ML	Fri Dec 14 11:50:19 2001 +0100
@@ -98,7 +98,7 @@
 
 fun mk_arity (t, ss, c) =
   let
-    val tfrees = ListPair.map TFree (Term.invent_names (length ss) "'", ss);
+    val tfrees = ListPair.map TFree (Term.invent_type_names [] (length ss), ss);
   in Logic.mk_inclass (Type (t, tfrees), c) end;
 
 fun dest_arity tm =