diff -r 51ed014406fa -r 5c5fdce3a4e4 src/HOL/Set.thy
--- a/src/HOL/Set.thy	Fri May 30 15:17:36 1997 +0200
+++ b/src/HOL/Set.thy	Fri May 30 15:19:58 1997 +0200
@@ -16,7 +16,7 @@
   set :: (term) term
 
 instance
-  set :: (term) {ord, minus}
+  set :: (term) {ord, minus, power}
 
 consts
   "{}"          :: 'a set                           ("{}")