diff -r 14bd6e5985f1 -r a75558a4ed37 src/HOL/Subst/Setplus.thy
--- a/src/HOL/Subst/Setplus.thy	Thu May 15 12:29:59 1997 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,14 +0,0 @@
-(*  Title:      Substitutions/setplus.thy
-    Author:     Martin Coen, Cambridge University Computer Laboratory
-    Copyright   1993  University of Cambridge
-
-Minor additions to HOL's set theory
-*)
-
-Setplus = Set + 
-
-rules
-
-  ssubset_def    "A < B == A <= B & ~ A=B"
-
-end