proposition: Lemma is_perm_mx1 n : is_perm_mx (1%:M : 'M_n).
proof: Proof. by rewrite -perm_mx1 perm_mx_is_perm. 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)