proposition: Lemma rank_col_mx0 m n p (A : 'M_(m, n)) : \rank (col_mx A (0 : 'M_(p, n))) = \rank A.
proof: Proof. by rewrite -addsmxE addsmx0. 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)