--- a/src/HOL/Sexp.thy Tue Jun 30 20:49:49 1998 +0200
+++ b/src/HOL/Sexp.thy Tue Jun 30 20:50:34 1998 +0200
@@ -6,7 +6,7 @@
S-expressions, general binary trees for defining recursive data structures
*)
-Sexp = Univ +
+Sexp = Univ + Inductive +
consts
sexp :: 'a item set