Let $T^2$ be a smooth compact surface and let $p\in T^2$. Suppose that $T^2$ admits a symmetric $\left(0,2\right)$-tensor $g$ which is a flat Riemannian metric restricted to $T^2-\{p\}$. Is it true that $\chi(T)=0$?
Flat metric on compact surface minus a point
Gianni del Fiore
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