intros; intro.
inversion H; simpl in H1.
cut (x = y).
intro EQ; rewrite EQ in H2; inversion H2; auto.
rewrite H0 in H1; injection H1; auto.
Qed.

Lemma NoMACObjChange2 :
forall (s : SFSstate) (o : OBJECT), ~ MACObjCtrlAttrHaveChanged s s o.