proposition: Lemma det_map_mx n' (A : 'M_n') : \det A^f = f (\det A).
proof: Proof. rewrite rmorph_sum //; apply: eq_bigr => s _. rewrite rmorphM /= rmorph_sign rmorph_prod; congr (_ * _). by apply: eq_bigr => i _; rewrite mxE. 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)