Hint Resolve @compareM_refl.
(* Rules for the BI connectives *)

Lemma split_sepcon {A} {JA: Join A}{PA: Perm_alg A}{AG: ageable A}{XA: Age_alg A} : forall (P Q R S:pred A),
P |-- Q ->
R |-- S ->
(P * R) |-- (Q * S).