Solution (source code)

= Solution

The <trace> is invariant under a <similarity transformation>, by cyclicity of the trace:
$$
\boxed{\chi_{\widetilde D}(g)=\operatorname{tr}(SD(g)S^{-1})=\operatorname{tr}(D(g)S^{-1}S)=\chi_D(g).}
$$
Hence <equivalent representations> have the same <character of a representation>.