Definition identity_rmap' : R.rmap' := exist valid (fun _: AV.address => R.NO) AV.valid_empty.Definition identity_rmap (n:nat) : rmap := R.squash (n, identity_rmap').

Lemma ageN_squash : forall d n rm, le d n -> ageN d (squash (n, rm)) = Some (squash ((n - d)%nat, rm)).