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Jul 8, 2020 at 14:38 comment added student Thank you very much! This makes a lot of sense.
Jul 6, 2020 at 20:42 comment added Sebastian You have $\phi^*\delta=\tfrac{1}{(\tilde x^2+\tilde y^2)^2} \delta$. Therefore you need that $e^{2u\circ\phi(\tilde x,\tilde y)} \tfrac{1}{(\tilde x^2+\tilde y^2)^2}$ extends smoothly to $0$ and that the value of this function at $0$ is bigger than 0.
Jul 6, 2020 at 14:48 comment added student Sorry for the typo in the previous comment. It should be $e^{2u}=1/(1+x^2+4y^2)$. Could you give me a reference on how to use the conformal coordinates you gave to proceed computation?
Jul 6, 2020 at 14:29 comment added student Thank you very much for your post. Yes, the question you posted is really what I want to understand. I have trouble in understanding why the metric completion under the metric $g=e^{2u}\delta$ implies that such completed metric is also Riemannian, or why it is also a smooth extension of the original metric defined only on $\mathbb{R}^2$? For example, given $e^{2u}=1/(x^2+4y^2)$, what are such $M$, $U$ and $\phi$? Sorry I have a very poor basis of Riemannian geometry.
Jul 6, 2020 at 13:00 history answered Sebastian CC BY-SA 4.0