English

On $\kappa$-bounded and $M$-compact reflections of topological spaces

General Topology 2021-11-01 v1

Abstract

For a topological space XX its reflection in a class T\mathsf T of topological spaces is a pair (TX,iX)(\mathsf T X,i_X) consisting of a space TXT\mathsf T X\in\mathsf T and continuous map iX:XTXi_X:X\to \mathsf T X such that for any continuous map f:XYf:X\to Y to a space YTY\in\mathsf T there exists a unique continuous map fˉ:TXY\bar f:\mathsf T X\to Y such that f=fˉiXf=\bar f\circ i_X. In this paper for an infinite cardinal κ\kappa and a nonempty set MM of ultrafilters on κ\kappa, we study the reflections of topological spaces in the classes Hκ\mathsf H_\kappa of κ\kappa-bounded Hausdorff spaces and HM\mathsf H_M of MM-compact Hausdorff spaces (a topological space XX is κ\kappa-bounded if the closures of subsets of cardinality κ\le\kappa in XX are compact; XX is MM-compact if any function x:κXx:\kappa\to X has a pp-limit in MM for every ultrafilter pMp\in M).

Keywords

Cite

@article{arxiv.1910.09186,
  title  = {On $\kappa$-bounded and $M$-compact reflections of topological spaces},
  author = {Taras Banakh},
  journal= {arXiv preprint arXiv:1910.09186},
  year   = {2021}
}

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17 pages