English

$\omega$-well-filtered spaces, revisited

General Topology 2024-09-04 v1

Abstract

We prove that a T0T_0 topological space is ω\omega-well-filtered if and only if it does not admit either the natural numbers with the cofinite topology or with the Scott topology as its closed subsets in the strong topology. Based on this, we offer a refined topological characterization for the ω\omega-well-filterification of T0T_0-spaces and solve a problem posed by Xiaoquan Xu. In the setting of second countable spaces, we also characterise sobriety by convergences of certain Π20\Pi^0_2-Cauchy subsets of the spaces.

Keywords

Cite

@article{arxiv.2409.01551,
  title  = {$\omega$-well-filtered spaces, revisited},
  author = {Hualin Miao and Xiaodong Jia and Ao Shen and Qingguo Li},
  journal= {arXiv preprint arXiv:2409.01551},
  year   = {2024}
}
R2 v1 2026-06-28T18:32:06.660Z