--- a/src/HOL/Library/Countable_Set.thy Sun Nov 02 17:16:01 2014 +0100
+++ b/src/HOL/Library/Countable_Set.thy Sun Nov 02 17:20:45 2014 +0100
@@ -3,7 +3,7 @@
Author: Andrei Popescu
*)
-header {* Countable sets *}
+section {* Countable sets *}
theory Countable_Set
imports Countable Infinite_Set