rewrite R.unsquash_squash.
simpl.
apply extensionality; intro l.
unfold compose; simpl; auto.
Qed.

Lemma make_rmap (f: AV.address -> resource) (V: AV.valid (res_option oo f))
(n: nat) (H: resource_fmap (approx n) oo f = f) :
{phi: rmap | level phi = n /\ resource_at phi = f}.