Timeline for direct image functor
Current License: CC BY-SA 2.5
10 events
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| Apr 13, 2017 at 12:58 | history | edited | CommunityBot |
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| Dec 9, 2010 at 17:36 | history | edited | Francesco Polizzi | CC BY-SA 2.5 |
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| Dec 9, 2010 at 17:12 | history | edited | Francesco Polizzi | CC BY-SA 2.5 |
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| Dec 9, 2010 at 16:50 | comment | added | Francesco Polizzi | @Steven: Actually it was not a counterexample :-) I was too concentrated to the non-vanishing of $R^1f_∗$ and I did not think about the original question. I've edited the post, now it's ok... | |
| Dec 9, 2010 at 16:47 | history | edited | Francesco Polizzi | CC BY-SA 2.5 |
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| Dec 9, 2010 at 16:41 | history | edited | Francesco Polizzi | CC BY-SA 2.5 |
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| Dec 9, 2010 at 16:28 | comment | added | t3suji | There are simple counterexamples though. For instance, if $f$ is the map to a point, the local freeness condition is vacuous, but the sequence of direct images (which are basically the spaces of global sections) does not need to be exact. (Of course, you can't construct a counterexample with a split exact sequence.) | |
| Dec 9, 2010 at 16:21 | comment | added | Steven Landsburg | This does not appear to be a counterexample. | |
| Dec 9, 2010 at 16:21 | history | edited | Francesco Polizzi | CC BY-SA 2.5 |
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| Dec 9, 2010 at 16:15 | history | answered | Francesco Polizzi | CC BY-SA 2.5 |