Section RAMIF_PLAIN.
Context {A : Type}.
Context {ND : NatDed A}.
Context {SL : SepLog A}.

(* Using split to prove frame will lead to a simpler proof. *)
(* But it requires a unitary separation logic.              *)
Lemma frame: forall g l g' l' F, g |-- l * (l' -* g') -> g * F |-- l * (l' -* g' * F).