Timeline for Is the collection scheme provable in ZF-Regularity?
Current License: CC BY-SA 4.0
4 events
| when toggle format | what | by | license | comment | |
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| Sep 13, 2020 at 10:02 | comment | added | Hanul Jeon | Your question is already answered in Mathematics Stackexchange. See the following question and answer. | |
| Sep 13, 2020 at 7:27 | comment | added | Emil Jeřábek | I don’t know who invented the following model: consider a model of $\mathrm{ZFC}^-$ of the form $\bigcup_{\alpha\in\mathrm{Ord}}V_\alpha(A)$ where $A$ is a countable infinite set of Quine atoms, and let $M$ be its submodel consisting of sets whose transitive closure includes only finitely many atoms from $A$. Then $M$ is a model of $\mathrm{ZFC}^-$ where collection fails (specifically, the model satisfies $\forall n\in\omega\,\exists x\,|\mathrm{tc}(x)\cap A|\ge n$, but not $\exists X\,\forall n\in\omega\,\exists x\in X\dots$). | |
| Sep 12, 2020 at 23:06 | history | edited | Zuhair Al-Johar | CC BY-SA 4.0 |
deleted 2 characters in body
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| Sep 12, 2020 at 21:40 | history | asked | Zuhair Al-Johar | CC BY-SA 4.0 |