proposition: Lemma row_free_castmx m1 m2 n (A : 'M_(m1, n)) e : row_free (castmx e A : 'M_(m2, n)) = row_free A.
proof: Proof. by rewrite /row_free eqmx_cast; congr (_ == _); rewrite e.1. 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)