Timeline for Flat cohomology of an ordinary liftable Calabi-Yau threefold
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
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| Sep 1, 2015 at 11:08 | comment | added | Oli Gregory | Thinking about it, I guess that a generic quintic threefold satisfies the hypotheses and provides a counter-example. Thanks to Daniel Litt for pointing this out; I definitely should've thought through that case. | |
| Jul 28, 2015 at 7:53 | comment | added | Oli Gregory | @WillSawin Yes, I had come to the same conclusion but I was rather hoping that somebody here would tell me that the hypotheses excludes this sort of thing. For example, in the K3 surface case I mentioned, this all works out because $k$ is perfect. Unfortunately I tend to agree with you that this seems false, which is rather a nuisance for the construction I had in mind... | |
| Jul 28, 2015 at 4:10 | comment | added | Will Sawin | This seems false, because the Picard group might be $\mathbb Z$, in which case your formula shows that the cohomology group is $\mathbb Q_p/\mathbb Z_p$. | |
| Jul 27, 2015 at 9:25 | history | edited | Oli Gregory | CC BY-SA 3.0 |
edited title
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| Jul 27, 2015 at 9:16 | history | asked | Oli Gregory | CC BY-SA 3.0 |