proposition: Lemma bound_meetC : commutative bound_meet.
proof: Proof. case=> [? ?|[]][? ?|[]] //=; rewrite meetC; congr BSide. by case: lcomparableP; rewrite ?orbF // orbC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(div fintype bigop order ssralg finset fingroup) mathcomp(ssrnum)