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

Lemma NoDACChange2 :
forall (s : SFSstate) (o : OBJECT), ~ DACCtrlAttrHaveChanged s s o.