proposition: Lemma memv_pi U V w : (daddv_pi U V) w \in U.
proof: Proof. by rewrite unlock memvE /subsetv genmxE /= r2vK proj_mx_sub. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)