src/HOL/Tools/Sledgehammer/sledgehammer_fact_filter.ML

--- a/src/HOL/Tools/Sledgehammer/sledgehammer_fact_filter.ML	Tue Jun 22 18:31:49 2010 +0200
+++ b/src/HOL/Tools/Sledgehammer/sledgehammer_fact_filter.ML	Tue Jun 22 18:47:45 2010 +0200
@@ -40,7 +40,7 @@
 open Sledgehammer_HOL_Clause
 
 (* Experimental feature: Filter theorems in natural form or in CNF? *)
-val use_natural_form = ref false
+val use_natural_form = Unsynchronized.ref false
 
 type relevance_override =
   {add: Facts.ref list,