English

On supercompactness of $\omega_1$

Logic 2019-04-04 v1

Abstract

This paper studies structural consequences of supercompactness of ω1\omega_1 under ZF\sf{ZF}. We show that the Axiom of Dependent Choice (DC)(\sf{DC}) follows from "ω1\omega_1 is supercompact". "ω1\omega_1 is supercompact" also implies that AD+\sf{AD}^+, a strengthening of the Axiom of Determinacy (AD)(\sf{AD}), is equivalent to ADR\sf{AD}_\mathbb{R}. It is shown that "ω1\omega_1 is supercompact" does not imply AD\sf{AD}. The most one can hope for is Suslin co-Suslin determinacy. We show that this follows from "ω1\omega_1 is supercompact" and Hod Pair Capturing (HPC)(\sf{HPC}), an inner-model theoretic hypothesis that imposes certain smallness conditions on the universe of sets. "ω1\omega_1 is supercompact" on its own implies that every Suslin co-Suslin set is the projection of a determined (in fact, homogenously Suslin) set. "ω1\omega_1 is supercompact" also implies all sets in the Chang model have all the usual regularity properties, like Lebesgue measurability and the Baire property.

Keywords

Cite

@article{arxiv.1904.01815,
  title  = {On supercompactness of $\omega_1$},
  author = {Daisuke Ikegami and Nam Trang},
  journal= {arXiv preprint arXiv:1904.01815},
  year   = {2019}
}