(** ** Properties of [drop_perm]. *)

Axiom load_drop:
forall m b lo hi p m', drop_perm m b lo hi p = Some m' ->
forall chunk b' ofs,
b' <> b \/ ofs + size_chunk chunk <= lo \/ hi <= ofs \/ perm_order p Readable ->
load chunk m' b' ofs = load chunk m b' ofs.