Section IntervalChoice.
Variable T : choiceType.
Definition itv_bound_porderMixin :=
LePOrderMixin lt_bound_def le_bound_refl le_bound_anti le_bound_trans.
Canonical itv_bound_porderType :=
POrderType (itv_bound_display disp) (itv_bound T) itv_bound_porderMixin.

Lemma subitv_trans : transitive subitv.