proposition: Lemma le_succ_succ : forall a b, nf a -> nf b -> a <= b -> succ a <= succ b.
proof: Proof. destruct 3. subst a;left;auto. right. apply lt_succ_succ;auto. Qed.
imports: Arith Omega Compare_dec Relations Wellfounded Tools More_nat Wf_nat AccP not_decreasing ArithRing term rpo List