Timeline for Does every map $K(\mathbb{Z}, n) \to K(\mathbb{Z}/m, n + k)$ factor through $K(\mathbb{Z}/m, n)$?
Current License: CC BY-SA 4.0
15 events
when toggle format | what | by | license | comment | |
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Mar 5, 2021 at 14:41 | answer | added | John Rognes | timeline score: 2 | |
Feb 19, 2021 at 23:05 | answer | added | John Rognes | timeline score: 9 | |
S Dec 17, 2020 at 23:04 | history | bounty ended | CommunityBot | ||
S Dec 17, 2020 at 23:04 | history | notice removed | CommunityBot | ||
S Dec 9, 2020 at 21:29 | history | bounty started | Michael Albanese | ||
S Dec 9, 2020 at 21:29 | history | notice added | Michael Albanese | Draw attention | |
Aug 26, 2020 at 1:39 | comment | added | John Greenwood | @DylanWilson well played, sir | |
Aug 26, 2020 at 1:27 | comment | added | Dylan Wilson | @JohnGreenwood nice! but I guess there's a negative answer for n=k=0 ! | |
Aug 25, 2020 at 21:36 | history | edited | Michael Albanese | CC BY-SA 4.0 |
Edited to maintain consistency.
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Aug 25, 2020 at 7:28 | comment | added | John Greenwood | Along with $m=2$, there is also a positive answer for $n=1$ :) | |
Aug 24, 2020 at 21:23 | comment | added | Dylan Wilson | sorry- I deleted my previous answer because I can't seem to make it work without basically just doing the whole computation anyway... maybe one needs to extract something from the Cartan seminar? It would be nice if there was a clean argument like Tim's though... Messing around it seems like $\mathbb{Z}/m[B\mathbb{Z}]\to\mathbb{Z}/m[B\mathbb{Z}/m]$ has an $\mathbb{E}_{\infty}$-$\mathbb{Z}/m$-retract? (which would do it) But I don't really trust that I didn't obscure some error while doing that... if I end up trusting that, I will update the post. | |
Aug 24, 2020 at 18:44 | comment | added | Tim Campion | Maybe for context one should point out that for stable cohomology operations, the answer is yes. That is, any map of spectra $\Sigma^n H\mathbb Z \to \Sigma^{n+k} H\mathbb Z / m$ commutes with multiplication by $m$ (which is null on $\Sigma^{n+k} H\mathbb Z / m$), and so descends, via the cofiber sequence $\Sigma^n H\mathbb Z \xrightarrow m \Sigma^n H\mathbb Z \to \Sigma^n H\mathbb Z / m$, to a map $\Sigma^n H\mathbb Z / m \to \Sigma^{n+k} H\mathbb Z / m$. | |
Aug 24, 2020 at 17:45 | history | edited | Michael Albanese | CC BY-SA 4.0 |
Edited title so that it is consistent with the question (which was edited earlier)
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Aug 24, 2020 at 13:23 | history | edited | Phil Tosteson | CC BY-SA 4.0 |
Changed notation to avoid confusion with m-adics
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Aug 24, 2020 at 13:10 | history | asked | Michael Albanese | CC BY-SA 4.0 |