End CfDetOps.
Definition cfcenter (gT : finGroupType) (G : {set gT}) (phi : 'CF(G)) :=
if phi \is a character then [set g in G | `|phi g| == phi 1%g] else cfker phi.
Notation "''Z' ( phi )" := (cfcenter phi) : cfun_scope.
Section Center.
Variable (gT : finGroupType) (G : {group gT}).
Implicit Types (phi chi : 'CF(G)) (H : {group gT}).

(* This is Isaacs (2.27)(a). *)
Lemma cfcenter_repr n (rG : mx_representation algCF G n) :
'Z(cfRepr rG)%CF = rcenter rG.