proposition: Lemma mxrowD m (R_ R'_ : forall j, 'M[V]_(m, q_ j)) : \mxrow_j (R_ j + R'_ j) = \mxrow_j (R_ j) + \mxrow_j (R'_ j).
proof: Proof. by apply/matrixP=> i j; rewrite !mxE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)