diff -r c7f04a008c9c -r 043ef82000b4 CookBook/Recipes/Sat.thy
--- a/CookBook/Recipes/Sat.thy	Wed Mar 18 03:03:51 2009 +0100
+++ b/CookBook/Recipes/Sat.thy	Wed Mar 18 03:27:15 2009 +0100
@@ -104,7 +104,7 @@
 done
 
 text {*
-  However, for prove anything more exciting you have to use a SAT solver
+  However, for proving anything more exciting you have to use a SAT solver
   that can produce a proof. The internal one is not usuable for this. 
 
   \begin{readmore}