proposition: Lemma rank_row_0mx m n p (A : 'M_(m, n)) : \rank (row_mx (0 : 'M_(m, p)) A) = \rank A.
proof: Proof. by rewrite -mxrank_tr -[RHS]mxrank_tr tr_row_mx trmx0 rank_col_0mx. 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 finalg zmodp matrix)