diff -r efd2b952f425 -r ccf2cbe86d70 src/HOL/IMP/Util.thy
--- a/src/HOL/IMP/Util.thy	Thu Dec 01 15:41:58 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,25 +0,0 @@
-(* Author: Tobias Nipkow *)
-
-theory Util imports Main
-begin
-
-subsection "Show sets of variables as lists"
-
-text {* Sets may be infinite and are not always displayed by element 
-  if computed as values. Lists do not have this problem. 
-
-  We define a function @{text show} that converts a set of
-  variable names into a list. To keep things simple, we rely on
-  the convention that we only use single letter names.
-*}
-definition 
-  letters :: "string list" where
-  "letters = map (\<lambda>c. [c]) chars"
-
-definition 
-  "show" :: "string set \<Rightarrow> string list" where
-  "show S = filter (\<lambda>x. x \<in> S) letters" 
-
-value "show {''x'', ''z''}"
-
-end