Timeline for Smooth morphism to homogeneous spaces and fibers
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 8, 2015 at 18:47 | vote | accept | Ron | ||
| Jun 30, 2015 at 18:32 | comment | added | Allen Knutson | I usually use "$f$ is equivariant". | |
| Jun 30, 2015 at 16:44 | answer | added | Jason Starr | timeline score: 1 | |
| Jun 30, 2015 at 13:02 | comment | added | Ron | @Starr: Thank you very much for your answer. I am reading one of your articles "Families of rationally simply connected varieties over surface and torsors for semi-simple groups". In the first line of the proof of Lemma 15.7 you say that the considered evaluation map has isomorphic fibers because the target is homogeneous. I was trying to understand this statement. | |
| Jun 30, 2015 at 12:59 | comment | added | Jason Starr | Also, there is another example: starting with $X' = Y\times Z$ and with $N$ everywhere disjoint graphs of morphisms from $Y$ to $Z$, let $X$ be the blowing up of these graphs. Because of these examples, usually people ask for the weaker conclusion that the fibers are birational. Moret-Bailly's pencils are counterexamples to "birational triviality". | |
| Jun 30, 2015 at 12:14 | comment | added | Jason Starr | This question is similar to others that come up from time-to-time, and I will remind of the following (sorry to keep repeating this): Moret-Bailly constructed pencils of Abelian surfaces over $\mathbb{P}^1$ that are not isotrivial. | |
| Jun 30, 2015 at 11:54 | comment | added | Ron | Sorry, typo. Corrected now. | |
| Jun 30, 2015 at 11:54 | history | edited | Ron | CC BY-SA 3.0 |
edited body
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| Jun 30, 2015 at 11:48 | comment | added | Achim Krause | how's $Z$ related to the situation? | |
| Jun 30, 2015 at 10:32 | history | asked | Ron | CC BY-SA 3.0 |