Timeline for Extending Namba forcing to arbitrary lengths
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 9, 2023 at 23:23 | vote | accept | Zoorado | ||
| Jun 8, 2023 at 21:12 | answer | added | BDeBondt | timeline score: 6 | |
| Apr 21, 2023 at 14:12 | comment | added | Zoorado | I see. So the only case that remains is $Nb(\omega_1, \beta)$ for $\beta$ weakly inaccessible. | |
| Apr 20, 2023 at 12:08 | comment | added | Andreas Lietz | Jensen has in fact shown $Nb(\omega_1, \beta^+)$ for any choice of cardinal $\beta$ (assuming mild fragments of GCH, at least). He had special interest in the case that $\beta$ has cofinality $\omega_1$ as then his forcing preserves $\beta^+$, so $\beta^+$ becomes $\omega_2$ in the extension, which is impossible if $\beta$ is singular of cofinality $\neq\omega_1$. In any case, Jensen still gets $cf(\beta^+)>\omega$ in the extension which is all you require. | |
| Apr 16, 2023 at 5:33 | history | edited | Zoorado | CC BY-SA 4.0 |
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| Apr 15, 2023 at 19:05 | history | edited | Zoorado | CC BY-SA 4.0 |
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| Apr 15, 2023 at 17:45 | history | edited | Zoorado | CC BY-SA 4.0 |
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| Apr 15, 2023 at 11:40 | history | asked | Zoorado | CC BY-SA 4.0 |