Timeline for $\Delta^0_{\alpha}$ universal sets does not exist
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Jun 30, 2020 at 14:23 | comment | added | Alessandro Codenotti | Fair enough, I expected that but it was worth trying asking here before posting a new question asking for a reference, which I'll probably do soon | |
| Jun 30, 2020 at 13:39 | comment | added | Asaf Karagila♦ | I did not think about this for 9 years minus one week, I suppose. (Okay, probably bit less than that.) Sorry... :-) | |
| Jun 30, 2020 at 12:28 | comment | added | Alessandro Codenotti | I'm almost 10 years late, but did you ever find such a simple proof? In any case do you have a reference for the fact that for uncountable Polish $X,Y$, there is no $Y$-universal set for $\mathbf{\Delta}^0_\alpha(X)$? I know the simple argument in the $X=Y$ case, but I can't find a proof of the general result anywhere | |
| Oct 9, 2011 at 19:27 | answer | added | Rachid Atmai | timeline score: 1 | |
| Jul 7, 2011 at 20:54 | history | edited | Asaf Karagila♦ | CC BY-SA 3.0 |
added 244 characters in body
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| Jul 6, 2011 at 18:42 | history | asked | Asaf Karagila♦ | CC BY-SA 3.0 |