Abstract
We show that it is equiconsistent with \({\mathsf{ZF}}\) that Fodor’s lemma fails everywhere, and furthermore that the club filter on every regular cardinal is not even \({\sigma}\)-complete. Moreover, these failures can be controlled in a very precise manner.
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This paper is part of the author’s Ph.D. thesis written at the Hebrew University of Jerusalem under the supervision of Prof. Menachem Magidor.
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Karagila, A. Fodor’s lemma can fail everywhere. Acta Math. Hungar. 154, 231–242 (2018). https://doi.org/10.1007/s10474-017-0768-5
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DOI: https://doi.org/10.1007/s10474-017-0768-5
Key words and phrases
- symmetric extension
- Fodor’s lemma
- closed and unbounded filter
- iterated symmetric extension
- the axiom of choice