Exactly $n$-resolvable Topological Expansions
Abstract
For a cardinal, a space is -{\it resolvable} if admits -many pairwise disjoint -dense subsets; is {\it exactly} -{\it resolvable} if it is -resolvable but not -resolvable. The present paper complements and supplements the authors' earlier work, which showed for suitably restricted spaces and cardinals that , if -resolvable, admits an expansion , with Tychonoff if is Tychonoff, such that is -resolvable for all but is not -resolvable (cf. Theorem~3.3 of \cite{comfhu10}). Here the "finite case" is addressed. The authors show in ZFC for : (a) every -resolvable space admits an exactly -resolvable expansion ; (b) in some cases, even with Tychonoff, no choice of is available such that is quasi-regular; (c) if -resolvable, admits an exactly -resolvable quasi-regular expansion if and only if either is itself exactly -resolvable and quasi-regular or has a subspace which is either -resolvable and nowhere dense or is -resolvable. In particular, every -resolvable quasi-regular space admits an exactly -resolvable quasi-regular expansion. Further, for many familiar topological properties , one may choose so that if .
Keywords
Cite
@article{arxiv.1008.5371,
title = {Exactly $n$-resolvable Topological Expansions},
author = {W. W. Comfort and Wanjun Hu},
journal= {arXiv preprint arXiv:1008.5371},
year = {2023}
}