English

Pseudoradial spaces and copies of $\omega_1+1$

General Topology 2020-12-11 v1

Abstract

In this paper we compare the concepts of pseudoradial spaces and the recently defined strongly pseudoradial spaces in the realm of compact spaces. We show that MA+c=ω2\mathrm{MA}+\mathfrak{c}=\omega_2 implies that there is a compact pseudoradial space that is not strongly pseudoradial. We essentially construct a compact, sequentially compact space XX and a continuous function f:Xω1+1f:X\to\omega_1+1 in such a way that there is no copy of ω1+1\omega_1+1 in XX that maps cofinally under ff. We also give some conditions that imply the existence of copies of ω1\omega_1 in spaces. In particular, PFA\mathrm{PFA} implies that compact almost radial spaces of radial character ω1\omega_1 contain many copies of ω1\omega_1.

Keywords

Cite

@article{arxiv.1904.04416,
  title  = {Pseudoradial spaces and copies of $\omega_1+1$},
  author = {Angelo Bella and Alan Dow and Rodrigo Hernández-Gutiérrez},
  journal= {arXiv preprint arXiv:1904.04416},
  year   = {2020}
}