proposition: Lemma cap1mx n (A : 'M_n) : (1%:M :&: A = A)%MS.
proof: Proof. by rewrite unlock qidmx_eq1 eqxx capmx_nop_id. 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)