proposition: Lemma mx11_is_trig (M : 'M_1) : is_trig_mx M.
proof: Proof. by apply/is_trig_mxP => i j; rewrite !ord1 ltnn. 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)