diff -r 450c9b682a92 -r 4370e5f0fa3f src/HOL/ex/Puzzle.ML
--- a/src/HOL/ex/Puzzle.ML	Wed Feb 12 18:53:59 1997 +0100
+++ b/src/HOL/ex/Puzzle.ML	Wed Feb 12 18:54:39 1997 +0100
@@ -23,7 +23,7 @@
 by (subgoal_tac "f(na) <= f(f(na))" 1);
 by (fast_tac (!claset addIs [Puzzle.f_ax]) 2);
 by (rtac lessD 1);
-by (best_tac (!claset delrules [le_refl] 
+by (fast_tac (!claset delrules [order_refl] 
                       addIs [Puzzle.f_ax, le_less_trans]) 1);
 val lemma = result() RS spec RS mp;