(*Require Import VST.concurrency.cl_step_lemmas.*)
Set Bullet Behavior "Strict Subproofs".
(** Lemmas common to both parts of the progress/preservation simulation results *)
Definition pures_same phi1 phi2 := forall loc k pp, phi1 @ loc = PURE k pp <-> phi2 @ loc = PURE k pp.
Definition isVAL (r : resource) :=
match r with
| YES _ _ (VAL _) _ => Logic.True
| _ => False
end.

Lemma approx_approx n x : approx n (approx n x) = approx n x.