proposition: Lemma meet1x : left_id \top (@meet _ L).
proof: Proof. by move=> x; apply/eqP; rewrite meetC meetx1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)