Timeline for Is relative torsion freeness an open condition?
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Jun 29, 2017 at 8:52 | vote | accept | CommunityBot | ||
| Jun 28, 2017 at 19:33 | answer | added | Hephaistos | timeline score: 1 | |
| Jun 28, 2017 at 5:08 | answer | added | Jason Starr | timeline score: 0 | |
| Jun 27, 2017 at 17:43 | comment | added | Jason Starr | Typo correction: "central fiber" --> "generic fiber". | |
| Jun 27, 2017 at 17:32 | history | edited | Nate Eldredge | CC BY-SA 3.0 |
fix typo in title
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| Jun 27, 2017 at 17:20 | comment | added | Jason Starr | By generic flatness, there is a dense open subscheme of $S$ over which $\mathcal{E}$ is flat. Replacing $S$ by this open, the torsion-free locus is open in the domain $X$, cf. EGA IV_3, Th'eor`eme 12.1.1(ii), p. 174. Thus, the finitely many embedded primes of $\mathcal{E}$ are closed subsets of $X$ that are disjoint from the central fiber. The images of these subsets in $S$ are constructible subsets that do not contain the generic point of $S$. Thus, they are nowhere dense. The union of the closures is a proper closed subset. The open $U$ is the complement. | |
| Jun 27, 2017 at 17:05 | history | asked | user85435 | CC BY-SA 3.0 |