Definition bnd_from_init m := bounded_maps.bounded_map (snd (getMaxPerm m)) /\ (Mem.mem_access m).1 = fun z k => None.

Lemma mem_drop_perm_bounded_init:
forall m b lo hi P m',
bnd_from_init m ->
Mem.drop_perm m b lo hi P = Some m' ->
bnd_from_init m'.