proposition: Lemma row_mx0 m n1 n2 : row_mx 0 0 = 0 :> 'M_(m, n1 + n2).
proof: Proof. exact: row_mx_const. 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)