diff -r fd3ab8bcb69d -r b5030aaca2ab src/FOLP/ex/Prolog.thy
--- a/src/FOLP/ex/Prolog.thy	Tue May 03 15:00:00 1994 +0200
+++ b/src/FOLP/ex/Prolog.thy	Tue May 03 15:14:54 1994 +0200
@@ -9,7 +9,7 @@
 *)
 
 Prolog = FOL +
-types   list 1
+types   'a list
 arities list    :: (term)term
 consts  Nil     :: "'a list"
         ":"     :: "['a, 'a list]=> 'a list"            (infixr 60)