Definition rmap_age1 (k:rmap) : option rmap :=
match unsquash k with
| (O,_) => None
| (S n,x) => Some (squash (n,x))
end.
Definition rmap_unage (k:rmap) : rmap :=
match unsquash k with
| (n,x) => squash (S n, x)
end.

Lemma unevolve_identity_rmap :
forall w w':rmap, necR w w' -> identity w' -> identity w.