Timeline for Uniform amenability at infinity
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
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| Sep 14, 2021 at 12:46 | comment | added | YCor | @MikaeldelaSalle ah, thanks, indeed it seems to suggest it doesn't follow easily... And actually, if $S_{(\omega)}$ is the group of finitary permutations of $\omega$, its ultraproduct contains all countable residually finite groups if I'm correct. And there exists non-exact such groups, as proved by Osajda ArXiv link. | |
| Sep 14, 2021 at 12:09 | comment | added | Mikael de la Salle | @Ycor Isn't your question answered in the last paragraph of the question? | |
| Sep 14, 2021 at 12:02 | comment | added | YCor | Have you checked whether the ultraproduct characterization also works ($G$ uniformly exact iff $^\eta G$ is exact for some/every nonprincipal integral ultrafilter)? The result would indeed follow. In the case of amenability, the verification is pretty straightforward. | |
| Sep 14, 2021 at 12:00 | history | edited | YCor | CC BY-SA 4.0 |
fixed norm sign and long dash sign, improved link
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| Sep 14, 2021 at 9:42 | history | asked | Narutaka OZAWA | CC BY-SA 4.0 |