Timeline for Is a finite injective dominant unramified morphism birational?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Jul 11, 2021 at 16:34 | review | Close votes | |||
| Jul 16, 2021 at 3:01 | |||||
| Jul 11, 2021 at 9:52 | comment | added | Francesco Polizzi | See mathoverflow.net/questions/164937/… | |
| Jul 11, 2021 at 9:51 | comment | added | Francesco Polizzi | For varieties over $\mathbb{C}$, the birationality should be a consequence of the following result: If $f:X \to Y$ is a morphism of varieties and either $f$ is finite or $X$ and $Y$ are projective, then $f$ is an isomorphism if and only if $f$ is bijective and $\mathrm{d} f: T_x(X) \to T_{f(x)}(Y)$ is injective for all $x \in X$. | |
| Jul 11, 2021 at 9:30 | comment | added | Laurent Moret-Bailly | Welcome, new contributor. The answer is no: take $\mathrm{Spec}(\mathbb{C})\to \mathrm{Spec}(\mathbb{R})$. | |
| Jul 11, 2021 at 9:17 | review | First posts | |||
| Jul 11, 2021 at 12:56 | |||||
| Jul 11, 2021 at 9:16 | history | asked | Eduardo | CC BY-SA 4.0 |