proposition: Lemma mxrankM_maxl m n p (A : 'M_(m, n)) (B : 'M_(n, p)) : \rank (A *m B) <= \rank A.
proof: Proof. by rewrite -{1}(mulmx_base A) -mulmxA 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)