proposition: Lemma disj_diffr x y : x `&` y == \bot -> y `\` x = y.
proof: Proof. by rewrite meetC => /disj_diffl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)