Timeline for Theorems with finite sets of exceptions
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 15, 2021 at 6:13 | comment | added | José Hdz. Stgo. | @RobinSaunders: How do you like the following theorem? arxiv.org/pdf/1505.00647.pdf | |
| Oct 8, 2021 at 9:29 | answer | added | Gerry Myerson | timeline score: 1 | |
| Oct 7, 2021 at 9:30 | history | made wiki | Post Made Community Wiki by Stefan Kohl♦ | ||
| Oct 7, 2021 at 9:03 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Sep 7, 2021 at 9:09 | comment | added | Roland Bacher | Root systems: Four infinite families + exceptions. Regular polytopes: three infinite families plus two exceptions in dimension 3, three exceptions in dimension 4 (and infinitely many exceptions in dimension 2). | |
| Sep 7, 2021 at 8:48 | answer | added | bathalf15320 | timeline score: 0 | |
| Sep 7, 2021 at 8:22 | comment | added | Zach Teitler | The Alexander-Hirschowitz theorem: General collections of double points impose independent conditions on homogeneous forms, with a known list of exceptions. Equivalently, every secant variety of a Veronese variety has expected dimension, with a known list of exceptions. Apart from quadrics, there are 4 exceptions. | |
| Sep 7, 2021 at 7:07 | history | edited | YCor |
edited tags
|
|
| Sep 7, 2021 at 6:46 | comment | added | Francesco Polizzi | We have $\operatorname{Out}(S_n)=\{1\}$ for $n \neq 6$, whereas $\operatorname{Out}(S_6)=\mathbb{Z}_2$. | |
| Sep 7, 2021 at 0:31 | comment | added | Robin Saunders | @AlexandreEremenko I didn't add that one because it's on the Wikipedia article. | |
| Sep 7, 2021 at 0:30 | comment | added | Robin Saunders | @SamHopkins Thanks. I did search for similar questions, but there are many ways to word the concept, which makes those harder to find. I also didn't think to check math.stackexchange, which was an oversight. I'm happy for this to be closed if that's what others think best - I think the wording's a little more specific than the other MO question, but the stackexchange one has quite a few good answers. | |
| Sep 7, 2021 at 0:30 | comment | added | Alexandre Eremenko | Classification of finite simple groups is a notable example. Classification of finite subgroups of $SL(2,C)$ or $SO(3)$ has the same feature: 2 infinite series and few sporadic examples. | |
| Sep 7, 2021 at 0:20 | comment | added | Sam Hopkins | The MO question: mathoverflow.net/questions/393710/anomalous-phenomena | |
| Sep 7, 2021 at 0:19 | comment | added | Sam Hopkins | Someone asked a very similar question here a few months ago that was closed; also, a similar question on Math Stackexchange: math.stackexchange.com/questions/186103/… | |
| Sep 7, 2021 at 0:15 | history | asked | Robin Saunders | CC BY-SA 4.0 |