proposition: Lemma addvA : associative addV.
proof: Proof. by move=> U V W; apply/vs2mxP; rewrite !vs2mxD addsmxA submx_refl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)