--- a/src/FOL/ex/Natural_Numbers.thy Sun Nov 02 18:21:14 2014 +0100
+++ b/src/FOL/ex/Natural_Numbers.thy Sun Nov 02 18:21:45 2014 +0100
@@ -2,7 +2,7 @@
Author: Markus Wenzel, TU Munich
*)
-header {* Natural numbers *}
+section {* Natural numbers *}
theory Natural_Numbers
imports FOL