English

Coloring Cantor sets and resolvability of pseudocompact spaces

General Topology 2017-11-15 v2

Abstract

Let us denote by Φ(λ,μ)\Phi(\lambda,\mu) the statement that B(λ)=D(λ)ω\mathbb{B}(\lambda) = D(\lambda)^\omega, i.e. the Baire space of weight λ\lambda, has a coloring with μ\mu colors such that every homeomorphic copy of the Cantor set C\mathbb{C} in B(λ)\mathbb{B}(\lambda) picks up all the μ\mu colors. We call a space XX\, {\em π\pi-regular} if it is Hausdorff and for every non-empty open set UU in XX there is a non-empty open set VV such that VU\overline{V} \subset U. We recall that a space XX is called {\em feebly compact} if every locally finite collection of open sets in XX is finite. A Tychonov space is pseudocompact iff it is feebly compact. The main result of this paper is the following. Theorem. Let XX be a crowded feebly compact π\pi-regular space and μ\mu be a fixed (finite or infinite) cardinal. If Φ(λ,μ)\Phi(\lambda,\mu) holds for all λ<c^(X)\lambda < \widehat{c}(X) then XX is μ\mu-resolvable, i.e. contains μ\mu pairwise disjoint dense subsets. (Here c^(X)\widehat{c}(X) is the smallest cardinal κ\kappa such that XX does not contain κ\kappa many pairwise disjoint open sets.) This significantly improves earlier results of van Mill , resp. Ortiz-Castillo and Tomita.

Keywords

Cite

@article{arxiv.1702.02454,
  title  = {Coloring Cantor sets and resolvability of pseudocompact spaces},
  author = {István Juhász and Lajos Soukup and Zoltán Szentmiklóssy},
  journal= {arXiv preprint arXiv:1702.02454},
  year   = {2017}
}

Comments

8 pages

R2 v1 2026-06-22T18:12:49.167Z