src/HOL/Library/Prefix_Order.thy

--- a/src/HOL/Library/Prefix_Order.thy	Wed Jun 17 10:57:11 2015 +0200
+++ b/src/HOL/Library/Prefix_Order.thy	Wed Jun 17 11:03:05 2015 +0200
@@ -2,7 +2,7 @@
     Author:     Tobias Nipkow and Markus Wenzel, TU Muenchen
 *)
 
-section {* Prefix order on lists as order class instance *}
+section \<open>Prefix order on lists as order class instance\<close>
 
 theory Prefix_Order
 imports Sublist