English

First countable spaces without point-countable $\pi$-base

General Topology 2007-05-23 v1

Abstract

We answer several questions of V. Tka\v{c}uk from [Point-countable π\pi-bases in first countable and similar spaces, Fund. Math. 186 (2005), pp. 55--69.] by showing that (1) there is a ZFC example of a first countable, 0-dimensional Hausdorff space with no point-countable π\pi-base (in fact, the order of any π\pi-base of the space is at least ω\aleph_\omega); (2) if there is a κ\kappa-Suslin line then there is a first countable GO space of cardinality κ+\kappa^+ in which the order of any π\pi-base is at least κ\kappa; (3) it is consistent to have a first countable, hereditarily Lindel\" of regular space having uncountable π\pi-weight and ω1\omega_1 as a caliber (of course, such a space cannot have a point-countable π\pi-base).

Keywords

Cite

@article{arxiv.math/0703728,
  title  = {First countable spaces without point-countable $\pi$-base},
  author = {Istvan Juhasz and Lajos Soukup and Zoltan Szentmiklossy},
  journal= {arXiv preprint arXiv:math/0703728},
  year   = {2007}
}