src/HOL/subset.thy

Now Datatype.occs_in_prems prints the necessary warning ITSELF.

It is also easier to invoke and even works if the induction variable
is a parameter (rather than a free variable).

(*  Title:      HOL/subset.thy
    ID:         $Id$
    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
    Copyright   1994  University of Cambridge
*)

subset = Fun