proposition: Fact opredU : join_closed S.
proof: Proof. by move=> x y Sx Sy; rewrite joinEtotal; case: leP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)