English

Resolvability of spaces having small spread or extent

General Topology 2007-05-23 v1 Logic

Abstract

In a recent paper O. Pavlov proved the following two interesting resolvability results: (1) If a space XX satisfies Δ(X)>\ps(X)\Delta(X) > \ps(X) then XX is maximally resolvable. (2) If a T3T_3-space XX satisfies Δ(X)>\pe(X)\Delta(X) > \pe(X) then XX is ω\omega-resolvable. Here \ps(X)\ps(X) (\pe(X)\pe(X)) denotes the smallest successor cardinal such that XX has no discrete (closed discrete) subset of that size and Δ(X)\Delta(X) is the smallest cardinality of a non-empty open set in XX. In this note we improve (1) by showing that Δ(X)>\Delta(X) > \ps(X)\ps(X) can be relaxed to Δ(X)\Delta(X) \ge \ps(X)\ps(X). In particular, if XX is a space of countable spread with Δ(X)>ω\Delta(X) > \omega then XX is maximally resolvable. The question if an analogous improvement of (2) is valid remains open, but we present a proof of (2) that is simpler than Pavlov's.

Keywords

Cite

@article{arxiv.math/0609091,
  title  = {Resolvability of spaces having small spread or extent},
  author = {Istvan Juhasz and Lajos Soukup and Zoltan Szentmiklossy},
  journal= {arXiv preprint arXiv:math/0609091},
  year   = {2007}
}
R2 v1 2026-07-22T17:41:53.030Z