Definition no_preds (r: resource) :=
   match r with NO => True | YES _ _ pp => pp=NoneP | PURE _ pp => pp=NoneP end.

Lemma join_YES_pfullshare1: forall pp k p x y, join (YES (mk_lifted Share.top pp) k p) x y -> (NO, YES pfullshare k p) = (x,y).