proposition: Lemma vspace_modl U V W : (U <= W -> U + (V :&: W) = (U + V) :&: W)%VS.
proof: Proof. by move=> sUV; apply/vs2mxP; rewrite !(vs2mxD, vs2mxI); apply/eqmxP/matrix_modl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)