proposition: Lemma perm_mx1 n : perm_mx 1 = 1%:M :> 'M_n.
proof: Proof. exact: row_perm1. 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)