Asaf Karagila: Fodor’s lemma can fail at every cardinal

HUJI Logic Seminar
The next meeting of the Logic Seminar will take place in next Wednesday,
14/12, Ross Building 70, 16:00 — 18:00.

Speaker: Asaf Karagila

Title: Fodor’s lemma can fail at every cardinal
Abstract. Fodor’s lemma states that given a regressive function from an
uncountable regular $\kappa$ to itself must have a stationary fiber. We will
discuss the possible failure of this lemma at an arbitrary cardinal $\kappa$,
as well some provable facts about the club filters which are equivalent to
Fodor’s lemma in ZF. If time permits, we will outline two methods for
obtaining global failures.

This talk will be based on the paper: Fodor’s lemma can fail everywhere,
which can be found on arXiv, https://arxiv.org/abs/1610.03985

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