proposition: Lemma only_OO_is_grater_than_OO : forall y : Nat, Le OO y -> EqNat OO y.
proof: Proof. cofix u. intros y H. case H. apply EqNat_inj. apply OO_unfold. intros. rewrite OO_unfold. apply eqSUCC. apply u. assumption. Qed.
imports: Acc_and_Inf