Timeline for What is the generator of $\pi_9(S^2)$?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 5, 2020 at 12:25 | vote | accept | Alex Gavrilov | ||
| May 30, 2019 at 10:52 | comment | added | Alex Gavrilov | I think this description is good enough for me. (And now I do not mind moderators closing my question as a duplicate.) | |
| May 29, 2019 at 16:28 | comment | added | Ian Agol | @AlexGavrilov: a new answer to the other question gives a fairly explicit realization of the generator for $\pi_9 S^3$. mathoverflow.net/a/332750/1345 | |
| May 29, 2019 at 11:19 | comment | added | Ian Agol | @AlexGavrilov The element $nu$ is very explicit, and hence so is its 3-fold suspension (so the generator of $\pi_8(S^5)$). The other map is harder to describe, but in principle could be computed with a connection, which is essentially canonical from the homogeneity of the situation. I’ll try to add some details tomorrow. | |
| May 29, 2019 at 10:49 | comment | added | Alex Gavrilov | Thank you. What I want is to have a picture of the geometry. (Even if only a bit. Then, at least, I would not have to completely trust a topologist that all of this works.) To do this your way I would need to make sense of (1) the map $S^8\to S^5$ in $\pi_8 S^5$ and of (2) the geometry of $\pi_8 S^5\to \pi_9S^3$. Both things look rather obscure to me (even if I more or less understand the argument on the formal level). | |
| May 29, 2019 at 5:44 | history | answered | Ian Agol | CC BY-SA 4.0 |