proposition: Lemma comm_mx_stable_eigenspace (f g : 'M[F]_n) a : comm_mx f g -> stablemx (eigenspace f a) g.
proof: Proof. move=> cfg; rewrite comm_mx_stable_ker//. by apply/comm_mx_sym/comm_mxB => //; apply:comm_mx_scalar. 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)