--- a/src/HOL/ex/Quickcheck_Examples.thy Mon Dec 05 12:36:06 2011 +0100
+++ b/src/HOL/ex/Quickcheck_Examples.thy Mon Dec 05 12:36:19 2011 +0100
@@ -411,10 +411,9 @@
lemma
"xs = [] ==> hd xs \<noteq> x"
-quickcheck[exhaustive, potential = false, expect = no_counterexample]
-quickcheck[exhaustive, potential = true, expect = counterexample]
-quickcheck[random, potential = false, report = false, expect = no_counterexample]
-quickcheck[random, potential = true, report = false, expect = counterexample]
+quickcheck[exhaustive, expect = no_counterexample]
+quickcheck[random, report = false, expect = no_counterexample]
+quickcheck[random, report = true, expect = counterexample]
oops
lemma