--- a/src/HOL/Library/Boolean_Algebra.thy Mon Dec 10 11:24:08 2007 +0100
+++ b/src/HOL/Library/Boolean_Algebra.thy Mon Dec 10 11:24:09 2007 +0100
@@ -8,7 +8,7 @@
header {* Boolean Algebras *}
theory Boolean_Algebra
-imports Main
+imports PreList
begin
locale boolean =