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: HOLCF/Up2.thy
ID: $Id$
Author: Franz Regensburger
Copyright 1993 Technische Universitaet Muenchen
Class Instance u::(pcpo)po
*)
Up2 = Up1 +
instance u :: (pcpo)po (refl_less_up,antisym_less_up,trans_less_up)
end