Timeline for Is the following morphism etale
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 28, 2011 at 20:43 | comment | added | Kevin Buzzard | Very nice -- thanks to both of you. | |
| Jul 27, 2011 at 19:05 | comment | added | Laurent Moret-Bailly | @Torsten: You beat me by 3 minutes on this one. | |
| Jul 27, 2011 at 19:03 | comment | added | Laurent Moret-Bailly | @Kevin: Yes: $Y=$ union of the two diagonals in the plane, $Z=$ the $x$-axis, map= the $x$-projection. | |
| Jul 27, 2011 at 19:00 | comment | added | Torsten Ekedahl | @Kevin: Yes, start with an étale double cover $X\to Z$ with a fibre consisting of two points. Construct $Y$ as the nodal "curve" with these two points identified. | |
| Jul 27, 2011 at 17:43 | comment | added | Kevin Buzzard | If $Y$ is not normal then can the hypothesis of the question ever be true? i.e. does there ever exist $Z$ and some map $Y\to Z$ as in the question such that the induced map $X\to Z$ is etale with $X$ the normalization? | |
| Jul 27, 2011 at 16:41 | vote | accept | Homalor | ||
| Jul 27, 2011 at 16:34 | history | answered | Qing Liu | CC BY-SA 3.0 |