+naxiom DT: nat → Type.
+naxiom dt: ∀n. DT n.
+
+ninductive nnat (n: nat) (A:DT n): Type ≝
+ nO: nnat n A
+ | nS: mat n A → mat n A → nnat n A
+with mat: Type ≝
+ |mS : nnat n A → mat n A.
+
+nlet rec nnzero (n:nnat 0 (dt ?)) : nnat 0 (dt ?) ≝
+ match n return ? with
+ [ nO ⇒ nO 0 (dt ?)
+ | nS m _ ⇒ nmzero m ]
+and nmzero (m:mat 0 (dt ?)) : nnat 0 (dt ?) ≝
+ match m return ? with
+ [ mS n ⇒ nnzero n ].
+
+nrecord pair (n: nat) (x: DT n) (label: Type): Type ≝
+ { lbl:label; l: pair n x label; r: pair n x label}.