(** ** Properties of [store]. *)
(** [store] preserves block validity, permissions, access validity, and bounds. Moreover, a [store] succeeds if and only if the corresponding access is valid for writing. *)

Axiom store_valid_access_2:
forall chunk m1 b ofs v m2, store chunk m1 b ofs v = Some m2 ->
forall chunk' b' ofs' p,
valid_access m2 chunk' b' ofs' p -> valid_access m1 chunk' b' ofs' p.