English

On the reflection of the countable chain condition

General Topology 2018-04-25 v1

Abstract

We study the question of when an uncountable ccc topological space XX contains a ccc subspace of size 1\aleph_1. We show that it does if XX is compact Hausdorff and more generally if XX is Hausdorff with pct(X)1\mathrm{pct}(X) \leq \aleph_1. For each regular cardinal κ\kappa, an example is constructed of a ccc Tychonoff space of size κ\kappa and countable pseudocharacter but with no ccc subspace of size less than κ\kappa. We also give a ccc compact T1T_1 space of size κ\kappa with no ccc subspace of size less than κ\kappa.

Keywords

Cite

@article{arxiv.1804.09103,
  title  = {On the reflection of the countable chain condition},
  author = {Ramiro de la Vega},
  journal= {arXiv preprint arXiv:1804.09103},
  year   = {2018}
}

Comments

7 pages

R2 v1 2026-06-23T01:34:12.152Z