English

Quasi-Polish spaces and spaces of filters in second-order arithmetic

Logic 2026-05-15 v1

Abstract

The class of quasi-Polish spaces admits several equivalent representations, including UF spaces, NP spaces, Π20\mathbf{\Pi}_2^0 subspaces of P(N)\mathcal{P}(\mathbb{N}), and sober spaces of countably presented frames. In this paper, we formalize these structures within second-order arithmetic and conduct a systematic reverse mathematical analysis of the transitions between them.

Keywords

Cite

@article{arxiv.2605.15052,
  title  = {Quasi-Polish spaces and spaces of filters in second-order arithmetic},
  author = {Yuzuki Kaneko and Keita Yokoyama},
  journal= {arXiv preprint arXiv:2605.15052},
  year   = {2026}
}