(* Where should this sit? *)
Section Timeless.
Definition except0 P := P || |>FF.
Definition timeless P := |>P |-- except0 P.
Definition timeless' (P : mpred) := forall (a a' : rmap),
predicates_hered.app_pred P a' -> age a a' ->
predicates_hered.app_pred P a.

Lemma memory_block_timeless : forall sh n p,
timeless (memory_block sh n p).