\(\begin{align*}\varphi ({g^{ - 1}}hg) &= \varphi ({g^{ - 1}})\varphi (h)\varphi (g) \hfill \\
& = \,\varphi ({g^{ - 1}})\bar e\varphi (g) \hfill \\
& = \,\varphi ({g^{ - 1}})\varphi (g) \hfill \\
& = \varphi ({g^{ - 1}}g) \hfill \\
& = \varphi (e) \hfill \\
& = \bar e \hfill \\
\end{align*} \)