Timeline for When is 2 qualitatively different from 3?
Current License: CC BY-SA 4.0
89 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 2 at 8:38 | answer | added | Roland Bacher | timeline score: 2 | |
| Nov 28 at 19:47 | answer | added | user76284 | timeline score: 2 | |
| Nov 28 at 19:29 | answer | added | user76284 | timeline score: 1 | |
| Nov 28 at 18:44 | answer | added | user76284 | timeline score: 1 | |
| Nov 28 at 17:08 | answer | added | user76284 | timeline score: 1 | |
| Nov 26 at 0:21 | answer | added | Jesse Elliott | timeline score: 2 | |
| Nov 25 at 22:47 | answer | added | Sam Hopkins | timeline score: 0 | |
| Nov 25 at 20:24 | answer | added | Dan Romik | timeline score: 3 | |
| Nov 24 at 21:04 | answer | added | Turbo | timeline score: 3 | |
| Nov 17 at 22:21 | answer | added | Mohan | timeline score: 3 | |
| Nov 17 at 19:41 | answer | added | user76284 | timeline score: 4 | |
| Nov 17 at 19:09 | answer | added | user76284 | timeline score: 2 | |
| Nov 13 at 4:04 | answer | added | Daniel Weber | timeline score: 2 | |
| Nov 13 at 2:43 | answer | added | tkf | timeline score: 3 | |
| Nov 13 at 2:34 | answer | added | tkf | timeline score: 3 | |
| Nov 12 at 14:21 | answer | added | usul | timeline score: 4 | |
| Nov 12 at 10:10 | answer | added | Patrick Lambein | timeline score: 3 | |
| Nov 12 at 8:34 | answer | added | Lucenaposition | timeline score: 4 | |
| Nov 12 at 7:12 | comment | added | Ville Salo | cstheory.stackexchange.com/questions/47333/… some answers fit here. | |
| Nov 12 at 0:47 | answer | added | Nathaniel Johnston | timeline score: 2 | |
| Nov 11 at 23:21 | answer | added | Michael | timeline score: 3 | |
| Nov 11 at 16:58 | answer | added | Abhiram Natarajan | timeline score: 3 | |
| Nov 11 at 14:44 | answer | added | seldon | timeline score: 2 | |
| Nov 11 at 14:26 | comment | added | Miguel González | There is the so-called Hartshorne-Serre correspondence between codimension $2$ smooth subvarieties $Y \subset X$ (with some additional condition) of a smooth algebraic variety $X$ and certain rank $2$ vector bundles on $X$. There is no general analogue of Serre's construction in codimension $3$ or more. mathoverflow.net/questions/136797/… | |
| Nov 11 at 10:35 | comment | added | Peter LeFanu Lumsdaine | Many examples are of the form “for $n \geq 2$ things are simple; for $n \geq 3$ they’re complicated” (e.g. @BenJohnsrude’s comment of Kakeya sets, or Wojowu’s answer on free lattices). These seem much less notable or interesting than examples where the complexity of the problem is decreasing or non-monotonic in $n$ — where $n = 3$ is simple (and maybe also $n \geq 3$) but $n=2$ is complicated. | |
| Nov 11 at 8:05 | answer | added | HenrikRüping | timeline score: 3 | |
| Nov 11 at 7:50 | answer | added | Fedor Petrov | timeline score: 2 | |
| Nov 11 at 7:25 | answer | added | Phil Harmsworth | timeline score: 2 | |
| Nov 11 at 6:24 | answer | added | Fedor Petrov | timeline score: 3 | |
| Nov 11 at 5:17 | answer | added | Antoine Labelle | timeline score: 6 | |
| Nov 11 at 4:29 | answer | added | user369335 | timeline score: 3 | |
| Nov 11 at 2:43 | answer | added | Oscar Lanzi | timeline score: 6 | |
| Nov 10 at 22:00 | answer | added | user76284 | timeline score: 8 | |
| Nov 10 at 21:53 | answer | added | user76284 | timeline score: 6 | |
| Nov 10 at 21:48 | answer | added | C7X | timeline score: 5 | |
| Nov 10 at 21:33 | answer | added | user76284 | timeline score: 6 | |
| Nov 10 at 21:10 | comment | added | Sophie Swett | I wonder how many of these are explained by the fact that when you have 2 possibilities, eliminating one possibility is the same thing as finding the answer, but when you have 3 or more possibilities, those are not the same thing. | |
| Nov 10 at 18:23 | answer | added | user76284 | timeline score: 4 | |
| Nov 10 at 12:46 | comment | added | Kimball | Related: see math.stackexchange.com/q/3344266/11323 about 3 vs 4 | |
| Nov 10 at 12:42 | answer | added | Alexandre Eremenko | timeline score: 12 | |
| Nov 10 at 12:00 | answer | added | M. Winter | timeline score: 9 | |
| Nov 10 at 11:30 | comment | added | eddy ardonne | @YCor This also holds for the examples of the OP. Often counting $1,2,3,\infty$ makes sense. | |
| Nov 10 at 9:38 | comment | added | YCor | For almost all answers, it is rather "2" vs "$n\ge 3$". | |
| Nov 10 at 8:41 | answer | added | Carl Schildkraut | timeline score: 10 | |
| Nov 10 at 7:47 | answer | added | Alessandro Della Corte | timeline score: 11 | |
| Nov 10 at 7:41 | history | edited | Federico Poloni |
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| Nov 10 at 5:49 | answer | added | Fedor Petrov | timeline score: 2 | |
| Nov 10 at 4:13 | comment | added | user76284 | I'd like to see an answer to the why question. | |
| Nov 10 at 4:05 | answer | added | Tony Huynh | timeline score: 7 | |
| Nov 10 at 3:35 | answer | added | Keith Kearnes | timeline score: 10 | |
| Nov 10 at 2:28 | history | became hot network question | |||
| Nov 10 at 1:25 | answer | added | Tim Campion | timeline score: 5 | |
| Nov 10 at 0:35 | answer | added | John Doyle | timeline score: 23 | |
| Nov 9 at 23:43 | comment | added | Gerry Myerson | Maybe I was thinking of math.stackexchange.com/questions/1573308/… or of one of the many questions about "two" that are mentioned there under Linked or Related. Here on MO we have had mathoverflow.net/questions/915/… | |
| Nov 9 at 23:24 | comment | added | Gerry Myerson | I think there was a question about oddities of two some time ago, perhaps it was on math.stackexchange. | |
| Nov 9 at 23:23 | answer | added | Gerry Myerson | timeline score: 5 | |
| Nov 9 at 22:58 | answer | added | Corentin B | timeline score: 11 | |
| Nov 9 at 22:18 | answer | added | Wojowu | timeline score: 6 | |
| Nov 9 at 22:08 | answer | added | Corentin B | timeline score: 6 | |
| Nov 9 at 22:05 | answer | added | Stefan Kohl♦ | timeline score: 10 | |
| Nov 9 at 22:02 | answer | added | eddy ardonne | timeline score: 15 | |
| Nov 9 at 21:48 | answer | added | John Griesmer | timeline score: 12 | |
| Nov 9 at 21:32 | answer | added | Aleksei Kulikov | timeline score: 3 | |
| Nov 9 at 21:15 | answer | added | Gabe K | timeline score: 63 | |
| Nov 9 at 21:13 | answer | added | Denis Serre | timeline score: 6 | |
| Nov 9 at 21:09 | answer | added | eddy ardonne | timeline score: 13 | |
| Nov 9 at 20:48 | answer | added | Yemon Choi | timeline score: 5 | |
| Nov 9 at 20:24 | answer | added | Jean-Philippe Burelle | timeline score: 46 | |
| Nov 9 at 20:16 | answer | added | Wojowu | timeline score: 23 | |
| Nov 9 at 19:59 | answer | added | Mark Wildon | timeline score: 6 | |
| Nov 9 at 19:58 | history | made wiki | Post Made Community Wiki by David Roberts♦ | ||
| Nov 9 at 19:47 | answer | added | Jason Starr | timeline score: 3 | |
| Nov 9 at 19:47 | answer | added | eddy ardonne | timeline score: 8 | |
| Nov 9 at 19:46 | answer | added | Sam Hopkins | timeline score: 11 | |
| Nov 9 at 19:45 | comment | added | mathworker21 | Many statements about primes hold unless the prime is $2$. | |
| Nov 9 at 19:40 | answer | added | Burak | timeline score: 12 | |
| Nov 9 at 19:34 | answer | added | eddy ardonne | timeline score: 48 | |
| Nov 9 at 19:17 | answer | added | Keith | timeline score: 29 | |
| Nov 9 at 19:11 | answer | added | Keith Kearnes | timeline score: 8 | |
| Nov 9 at 19:06 | answer | added | Joel David Hamkins | timeline score: 18 | |
| Nov 9 at 18:57 | answer | added | Nathaniel Johnston | timeline score: 19 | |
| Nov 9 at 18:55 | comment | added | Ben Johnsrude | Something that doesn't quite fit the letter of the post, but perhaps the spirit: Kakeya sets are not too hard to understand in 2 dimensions, but become extremely difficult to understand in 3 dimensions. | |
| Nov 9 at 18:47 | answer | added | Nik Weaver | timeline score: 16 | |
| Nov 9 at 18:47 | comment | added | JP McCarthy | $x_1^n+x_2^n=0$ vs $x_1^n+x_2^n+x_3^n=0$... | |
| Nov 9 at 18:43 | answer | added | Mark Wildon | timeline score: 4 | |
| Nov 9 at 18:41 | comment | added | Federico Poloni | See this thread on Computational Science for many examples. | |
| Nov 9 at 18:40 | answer | added | Ahmad Beirami | timeline score: 5 | |
| Nov 9 at 18:37 | answer | added | David Manheim | timeline score: 41 | |
| Nov 9 at 18:27 | history | asked | Aryeh Kontorovich | CC BY-SA 4.0 |