diff -r 340df9f3491f -r 22f665a2e91c src/HOL/Bali/DefiniteAssignment.thy
--- a/src/HOL/Bali/DefiniteAssignment.thy	Sun Sep 11 22:56:05 2011 +0200
+++ b/src/HOL/Bali/DefiniteAssignment.thy	Mon Sep 12 07:55:43 2011 +0200
@@ -972,7 +972,7 @@
     case (UnOp unop e) 
     thus ?case
       by - (erule wt_elim_cases,cases unop,
-            (fastsimp simp add: assignsE_const_simp)+)
+            (fastforce simp add: assignsE_const_simp)+)
   next
     case (BinOp binop e1 e2)
     from BinOp.prems obtain e1T e2T