Timeline for Ideal class groups and extension of number fields
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 30, 2011 at 16:18 | vote | accept | Tom Bachmann | ||
| Dec 28, 2011 at 9:42 | answer | added | Niels | timeline score: 2 | |
| Dec 27, 2011 at 16:46 | comment | added | Bhargav | Pushforwards are exact along a finite morphism if you work in the etale topology (or Nisnevich, but not Zariski). So if you're working in the etale topology, the answer to (1) is always "yes," without much thought. In fact, even in the Zariski topology, in the special case at hand, one is in good shape: the stalks of R^1 f_* O_X* are given by Picard groups of semilocal rings of X; such rings are always PIDs (as X is Dedekind), so R^1 f_* O_X* does indeed vanish. | |
| Dec 27, 2011 at 16:19 | history | asked | Tom Bachmann | CC BY-SA 3.0 |