proposition: Lemma meetKI y x : x `&` (x `&` y) = x `&` y.
proof: Proof. by rewrite meetA meetxx. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)