# Field generated by character values need not be a splitting field

From Groupprops

(Redirected from Characters span class functions not implies splitting)

## Statement

### In characteristic zero

It is possible to have a finite group such that the Field generated by character values (?) in characteristic zero is not a Splitting field (?).

## Related facts

- Field generated by character values is splitting field implies it is the unique minimal splitting field
- Rational not implies rational-representation

## Proof

`Further information: quaternion group, faithful irreducible representation of quaternion group, linear representation theory of quaternion group`

The idea is to pick a group where one or more of the representations have Schur index greater than 1. The smallest example is the quaternion group, where the field generated by character values is the field of rational numbers (so the group is a rational group) but the two-dimensional faithful irreducible representation cannot be realized over the rationals or even over the reals (this can be shown via the indicator theorem).