(* 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. *)

Lemma local_andp_prop:  forall P Q, local P && prop Q = prop Q && local P.