(* Definition split_rmap (m: rmap) : rmap * rmap := (proj1_sig (make_rmap _ (split_rmap_valid1 m) (level m) (split_rmap_ok1 m)), proj1_sig (make_rmap _ (split_rmap_valid2 m) (level m) (split_rmap_ok2 m))). *)

Lemma nonlock_permission_bytes_share_join:
forall sh1 sh2 sh a n,
join sh1 sh2 sh ->
nonlock_permission_bytes sh1 a n *
nonlock_permission_bytes sh2 a n =
nonlock_permission_bytes sh a n.