+ intros. xomega.
+ induction 1.
- apply Mem.nextblock_storebytes in H;
rewrite H; xomega.
- apply Mem.nextblock_alloc in H.
rewrite H. clear. xomega.
- apply nextblock_freelist in H.
rewrite H; xomega.
- xomega.
Qed.

Lemma estep_unch_on_loc_not_writable m m' (E:e_step m m'): Mem.unchanged_on (loc_not_writable m) m m'.
*)