Ring generated by character values

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Definition

In characteristic zero or a prime characteristic

Suppose G is a finite group and fix a characteristic that is either zero or a prime not dividing the order of G. The ring generated by character values is the smallest ring containing all the character values of G over a splitting field.

Note that in prime characteristic, it is the same as the field generated by character values.

In characteristic zero, it is contained in a cyclotomic extension of the ring of integers \mathbb{Z}, because characters are cyclotomic integers.

Note that this differes from the character ring, which is the ring of characters as functions.