proposition: Lemma kermxpolyX n (g : 'M_n) : kermxpoly g 'X = kermx g.
proof: Proof. case: n => [|n] in g *; first by rewrite !thinmx0. by rewrite /kermxpoly horner_mx_X. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(div fintype tuple finfun bigop fingroup perm) mathcomp(ssralg zmodp matrix mxalgebra poly polydiv)