proposition: Lemma mxrank_add m n (A B : 'M_(m, n)) : \rank (A + B)%R <= \rank A + \rank B.
proof: Proof. by rewrite -{1}(mulmx_base A) -{1}(mulmx_base B) -mul_row_col mulmx_max_rank. 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)