proposition: Lemma rstabs_conj m (U : 'M_(m, n)) : rstabs rGB U = rstabs rG (U *m B).
proof: Proof. apply/setP=> x; rewrite !inE rconj_mxE !mulmxA. by rewrite -{2}[U](mulmxK uB) submxMfree // row_free_unit unitmx_inv. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime) mathcomp(ssralg poly polydiv finset fingroup morphism) mathcomp(perm automorphism quotient finalg action zmodp) mathcomp(commutator cyclic center pgroup matrix mxalgebra) mathcomp(mxpoly)