proposition: Lemma lt0B x y : x < y -> \bot < y `\` x.
proof: Proof. by move=> ?; rewrite lt_leAnge le0x leBLR joinx0 /= lt_geF. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)