proposition: Lemma memv_pi2 U V w : (addv_pi2 U V) w \in V.
proof: Proof. exact: memv_pi. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)