(* Lemma ENTAIL_normal_ret_assert: forall Delta P Q ek vl, (ek = EK_normal -> vl = None -> ENTAIL Delta, P |-- Q) -> ENTAIL Delta, normal_ret_assert P ek vl |-- normal_ret_assert Q ek vl. *)

(* Specifications: *)
Lemma local_andp_prop:  forall P Q, local P && prop Q = prop Q && local P.
Lemma local_sepcon_assoc2:
forall P Q R, R * (local P && Q) = local P && (R * Q).