End Abelian.
Section AbelianQuotient.
Variables (gT : finGroupType) (G : {group gT}).
Variables (n : nat) (rG : mx_representation F G n).

(* Specifications: *)
Lemma center_kquo_cyclic : mx_irreducible rG -> cyclic 'Z(G / rker rG)%g.
Lemma der1_sub_rker :
group_splitting_field G -> mx_irreducible rG ->
(G^`(1) \subset rker rG)%g = (n == 1)%N.