Timeline for Direct image sheaf and tensor product (is the projection formula an isomorphism?)
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
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| Feb 22, 2012 at 17:57 | comment | added | user2035 | Well, you need some restrictive condition, be it the morphism being affine or $N$ being flat (or locally free, which is the same for coherent sheaves). | |
| Feb 22, 2012 at 11:29 | vote | accept | TonyS | ||
| Feb 22, 2012 at 11:28 | comment | added | TonyS | Thanks. It is so obvious now, finite morphisms are affine, so one can look at this like you say in affine charts. I always forget all the connections between the various properties of morphisms. In the projection formula given in Hartshorne, one sheaf has to be locally free, which is very restrictive, i like the version in EGA better. | |
| Feb 22, 2012 at 7:58 | history | answered | user2035 | CC BY-SA 3.0 |