Given the ring R of class functions on a finite group G, return G.
The centre of the character x of G, i.e. the subgroup of G consisting of those classes C of G for which |x(g)|, g in C, is equal to the degree of x.
The (minimal) coefficient field Q_m of the class function x.
The kernel of the character x of G, i.e. the normal subgroup of G consisting of those elements g for which x(g) = x(1).