proposition: Lemma joinxC x : x `|` ~` x = \top.
proof: Proof. by rewrite complE diffKU joinx1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)