Local Open Scope pred.

Lemma sub_wand {A} {JA: Join A}{PA: Perm_alg A}{SA: Sep_alg A}{AG: ageable A}{XA: Age_alg A} : forall G P P' Q Q',
G |-- P' >=> P ->
G |-- Q >=> Q' ->
G |-- (P -* Q) >=> (P' -* Q').