diff -r a2775776be3f -r edaf5a6ffa99 src/HOL/Predicate_Compile_Examples/Predicate_Compile_Quickcheck_Examples.thy
--- a/src/HOL/Predicate_Compile_Examples/Predicate_Compile_Quickcheck_Examples.thy	Tue Sep 07 11:51:53 2010 +0200
+++ b/src/HOL/Predicate_Compile_Examples/Predicate_Compile_Quickcheck_Examples.thy	Tue Sep 07 11:51:53 2010 +0200
@@ -187,7 +187,7 @@
 
 lemma
   "exec c s s' ==> exec (Seq c c) s s'"
-(*quickcheck[generator = predicate_compile_wo_ff, size=2, iterations=10]*)
+  quickcheck[generator = predicate_compile_wo_ff, size=2, iterations=20, expect = counterexample]
 oops
 
 subsection {* Lambda *}