proposition: Lemma block_mxKul : ulsubmx A = Aul.
proof: Proof. by rewrite /ulsubmx col_mxKu row_mxKl. 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)