proposition: Lemma vspace_modr U V W : (W <= U -> (U :&: V) + W = U :&: (V + W))%VS.
proof: Proof. by rewrite -!(addvC W) !(capvC U); apply: vspace_modl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)