Local Open Scope logic.
Fixpoint power_later (n:nat) P :=
match n with
| 0%nat => P
| S n' => later (power_later n' P)
end
.

Lemma power_later_andp: forall (n:nat) (P Q : mpred), power_later n (P && Q) = (power_later n P) && (power_later n Q).