Let $f:G_1 \rightarrow G_2$ be a local biholomorphism and $g:G_2 \rightarrow G_1 $ continious
such that $(f\circ g)(z)=z$
Proof that $g$ is a biholomorphism
I know that $g$ is biholomorphic if $g' \gt 0$ for all $z\in G_2$ and $g^{-1}$ is continious.
How do I know that $g$ is already a holomorphic function ?
Can someone give me a hint/ or explain why $g$ is holomorphic if $g$ is continous and satisfies the condition above ?