proposition: Lemma opredI (S : meetLatticeClosed T) : {in S &, forall u v, u `&` v \in S}.
proof: Proof. exact: opredI. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)