Timeline for How to solve this exercise about large countable ordinals?
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
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| S Aug 16, 2023 at 5:05 | history | suggested | C7X | CC BY-SA 4.0 |
Including name in case of link rot
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| Aug 15, 2023 at 19:28 | review | Suggested edits | |||
| S Aug 16, 2023 at 5:05 | |||||
| Aug 15, 2023 at 19:19 | answer | added | C7X | timeline score: 1 | |
| S Jul 9, 2023 at 17:16 | history | suggested | C7X | CC BY-SA 4.0 |
Citing admissibility and Pi_2-reflection
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| Jul 9, 2023 at 16:29 | comment | added | C7X | Maybe a more explicit mention of nested $\Sigma_2$-extendibility pairs in "Weak Systems of Determinacy and Arithmetical Quasi-Inductive Definitions" (arXiv 0905.4412): "For $k<\omega$ the classes $E_k$ we can think of as having depth $k$ in the '$\Sigma_2$-extendible limits of $\Sigma_2$-extendible ...' hierarchy: if $\gamma\in E_k$ then there are ordinals $\gamma=\mu_k\le\mu_{k-1}\le\ldots\le\mu_0<\nu_0<\nu_1<\ldots<\nu_k$ satisfying $L_{\mu_j}\prec_{\Sigma_2}L_{\nu_j}$ for $j\le k$." I am not sure if there is some compactness result that gives this property for all $k<\omega$ simultaneously. | |
| Jul 9, 2023 at 13:37 | review | Suggested edits | |||
| S Jul 9, 2023 at 17:16 | |||||
| Jun 15, 2023 at 13:44 | history | asked | Reflecting_Ordinal | CC BY-SA 4.0 |