proposition: Lemma omorphI : Order.meet_morphism f.
proof: Proof. by move=> x y; rewrite -!set_meet2 omorphSM !image_setU !image_set1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype choice order) mathcomp(ssrnat bigop classical_sets)