proposition: Lemma lt_wf_double_rec : forall P:nat -> nat -> Set, (forall n m, (forall p q, p < n -> P p q) -> (forall p, p < m -> P n p) -> P n m) -> forall n m, P n m.
proof: Proof. intros P Hrec p; pattern p; apply lt_wf_rec. intros n H q; pattern q; apply lt_wf_rec; auto. Defined.
imports: PeanoNat