proposition: Fact meet_lel x y : meet x y <= meet y x.
proof: Proof. have:= le_refl (meet x y); rewrite meetP => /andP [mlex mley]. by rewrite meetP mlex mley. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)