Timeline for Partial well-ordering of formulas
Current License: CC BY-SA 4.0
2 events
| when toggle format | what | by | license | comment | |
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| Apr 28, 2022 at 1:05 | comment | added | C7X | According to Rathjen's "The Realm of Ordinal Analysis", if we work in KPM and look at good $\Sigma_1$-definitions of ordinals, we get a proper superset of the canonical notation system $\mathcal T(\mathbf M)\cap\mathbf M$ (e.g. $\psi_{\omega_3^{CK}}(\omega_2^{CK}\varepsilon_0)\in\mathcal T(\mathbf M)\cap\mathbf M$, but there are recursive ordinals that aren't). This is still an overshot, but maybe if we just define this for $\Sigma_1$-formulae it will fit at least as well as when defined for all formulae. | |
| Feb 14, 2019 at 18:29 | history | asked | Dmytro Taranovsky | CC BY-SA 4.0 |