proposition: Lemma comm_mx_stable_ker (f g : 'M[F]_n) : comm_mx f g -> stablemx (kermx f) g.
proof: Proof. move=> comm_fg; apply/sub_kermxP. by rewrite -mulmxA -[g *m _]comm_fg mulmxA mulmx_ker mul0mx. 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)