Definition linear_irr := [set i | 'n_i == 1%N].

(* Specifications: *)
Lemma irr_degree_abelian : abelian G -> forall i, 'n_i = 1%N.
Lemma Wedderburn_subring_center i : ('Z('R_i) :=: mxvec 'e_i)%MS.
Lemma Wedderburn_center :
('Z(R_G) :=: \matrix_(i < #|sG|) mxvec 'e_(enum_val i))%MS.
Lemma card_irr : #|sG| = tG.
Section CenterMode.