diff -r bfe45b716dfc -r 2fbe5ce9845f src/HOL/Isar_examples/Peirce.thy
--- a/src/HOL/Isar_examples/Peirce.thy	Tue Oct 05 18:16:26 1999 +0200
+++ b/src/HOL/Isar_examples/Peirce.thy	Tue Oct 05 18:16:41 1999 +0200
@@ -5,7 +5,7 @@
 
 theory Peirce = Main:;
 
-text {* Peirce's law: examples of classical proof. *};
+section {* Examples of classical proof --- Peirce's law. *};
 
 theorem "((A --> B) --> A) --> A";
 proof;