HOL,ZF/Makefile: enclosed multiple "use" calls in parentheses. This
ensures that if one dies, all die. BUT NOT Pure/Makefile, where
PolyML.use"POLY" makes the identifier "use" visible.
(* Title: HOL/subset.thy
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1994 University of Cambridge
*)
subset = Fun