Timeline for Derivative of dual isogeny is pullback on $H^1$
Current License: CC BY-SA 4.0
4 events
| when toggle format | what | by | license | comment | |
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| Dec 28, 2021 at 19:21 | comment | added | Hank Scorpio | @PiotrAchinger aha, that's quite nice. Thanks for the insight. | |
| Dec 14, 2021 at 7:39 | comment | added | Piotr Achinger | Since pullback of line bundles agrees with pullback on $H^1(\mathcal{O}^*)$, you can use naturality of the short exact sequence $$ 0\to \mathcal{O}_X\to \mathcal{O}^*_{X[\varepsilon]}\to \mathcal{O}^*_X\to 0 $$ to conclude (where $X[\varepsilon] = X\times \operatorname{Spec}k[\varepsilon]/(\varepsilon^2)$). | |
| Dec 14, 2021 at 7:37 | comment | added | Piotr Achinger | (The last paragraph is Hartshorne Ex IV 4.15.) | |
| Dec 13, 2021 at 22:40 | history | asked | Hank Scorpio | CC BY-SA 4.0 |