{"title":"Constructing pseudo-τ-fine precompact groups","authors":"Dekui Peng , Gao Zhang","doi":"10.1016/j.topol.2026.109745","DOIUrl":null,"url":null,"abstract":"<div><div>Let <em>τ</em> be an uncountable cardinal. The notion of a <em>τ-fine</em> topological group was introduced by M.G. Tkachenko in 2021. More recently, H. Zhang et al. generalized this concept by defining pseudo-<em>τ</em>-fine topological groups to study certain factorization properties of continuous functions on topological groups. It is known that <em>τ</em>-fineness cannot coexist with precompactness in topological groups with uncountable character. In this paper, we investigate this problem further. We prove that, in topological groups with uncountable pseudocharacter, precompactness can coexist with pseudo-<em>τ</em>-fineness for some bounded <em>τ</em> but pseudocompactness can never.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"381 ","pages":"Article 109745"},"PeriodicalIF":0.5000,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Topology and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166864126000350","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/1/28 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Let τ be an uncountable cardinal. The notion of a τ-fine topological group was introduced by M.G. Tkachenko in 2021. More recently, H. Zhang et al. generalized this concept by defining pseudo-τ-fine topological groups to study certain factorization properties of continuous functions on topological groups. It is known that τ-fineness cannot coexist with precompactness in topological groups with uncountable character. In this paper, we investigate this problem further. We prove that, in topological groups with uncountable pseudocharacter, precompactness can coexist with pseudo-τ-fineness for some bounded τ but pseudocompactness can never.
期刊介绍:
Topology and its Applications is primarily concerned with publishing original research papers of moderate length. However, a limited number of carefully selected survey or expository papers are also included. The mathematical focus of the journal is that suggested by the title: Research in Topology. It is felt that it is inadvisable to attempt a definitive description of topology as understood for this journal. Certainly the subject includes the algebraic, general, geometric, and set-theoretic facets of topology as well as areas of interactions between topology and other mathematical disciplines, e.g. topological algebra, topological dynamics, functional analysis, category theory. Since the roles of various aspects of topology continue to change, the non-specific delineation of topics serves to reflect the current state of research in topology.
At regular intervals, the journal publishes a section entitled Open Problems in Topology, edited by J. van Mill and G.M. Reed. This is a status report on the 1100 problems listed in the book of the same name published by North-Holland in 1990, edited by van Mill and Reed.