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 corable_power_later: forall n P, corable P -> corable (power_later n P).
Ltac power_normalize :=
repeat (
try rewrite -> power_later_andp;
try rewrite -> power_later_sepcon;
try rewrite <- power_later_TT)
.