proposition: Lemma xrow_const i1 i2 a : xrow i1 i2 (const_mx a) = const_mx a.
proof: Proof. exact: row_perm_const. 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)