For representation of finite groups on complex vector space, I knows two facts:
If a representation is self-conjugate (it is equivalent to its complex conjugate), then its character function is real-valued.
A representation is determined by its character function.
So I wonder whether a real-valued character function means that this representation is self-conjugate. But I cannot give a proof now.
Is this true? Or, can you give a counter-example?
I think I found a way to prove this.
First, if it is self-conjugate, clearly the character is real-valued. On the other hand, if the character is real-valued, then by \begin{equation} \chi_{D^*}(g) = \operatorname{Tr}(D^*(g)) = \operatorname{Tr}(D(g))^* = \chi^*_{D}(g) = \chi_{D}(g) \end{equation} The conjugate representation has the same character, hence is equivalent to original representation. Hence this representation is self-conjugate.