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