proposition: Lemma memvB U : {in U &, forall u v, u - v \in U}.
proof: Proof. exact: rpredB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)