proposition: Lemma simmxPp m n {P : 'M[F]_(m, n)} {A B} : stablemx P A -> A ~_P B -> P *m A = B *m P.
proof: Proof. by move=> stablemxPA /eqP <-; rewrite mulmxKpV. 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)