Section POrder.
Implicit Types (T : porderType disp).
Definition porderMixin n T := [porderMixin of n.-tuple T by <:].
Canonical porderType n T := POrderType disp' (n.-tuple T) (porderMixin n T).

Lemma ltEtprod n T (t1 t2 : n.-tuple T) :
t1 < t2 = [exists i, tnth t1 i != tnth t2 i] &&
[forall i, tnth t1 i <= tnth t2 i].