proposition: Lemma nat_ind2 : forall (P : nat -> Prop), P O -> P (S O) -> (forall m, P m -> P (S (S m))) -> forall n, P n.
proof: Proof. intros P P0 P1 PSS ; apply nat_strong. assumption. intros [] HN. assumption. apply PSS, HN, Nat.le_succ_diag_r. Qed.
imports: Arith MyNat