{"title":"For any space X, either \\(C_p(X)\\) or \\(C_pC_p(X)\\) is \\(\\psi \\)-separable","authors":"J. A. Aguilar-Velázquez, V. V. Tkachuk","doi":"10.1007/s10474-026-01603-0","DOIUrl":null,"url":null,"abstract":"<div><p>We establish that, for any Tychonoff space <i>X</i>, at least one of the spaces <span>\\(C_p(X)\\)</span> and <span>\\(C_pC_p(X)\\)</span> has a dense subspace of countable pseudocharacter. Under MA, we give an example of a space <i>X</i> such that <span>\\(C_p(X)\\)</span> does not have a dense subspace of countable functional tightness. We also show that there exists a compact zero-dimensional space <i>K</i> such that <span>\\(C_p(K,\\{0,1\\})\\)</span> is exponentially separable while <i>K</i> is not a Sokolov space. For compact scattered spaces <i>K</i> of countable dispersion index, we show that <span>\\(C_p(K)\\)</span> has a dense exponentially separable subspace if and only if <i>K</i> is <span>\\(\\omega \\)</span>-monolithic. Our results provide answers to several published open questions.\n</p></div>","PeriodicalId":50894,"journal":{"name":"Acta Mathematica Hungarica","volume":"178 1","pages":"279 - 288"},"PeriodicalIF":0.6000,"publicationDate":"2026-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10474-026-01603-0.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Mathematica Hungarica","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s10474-026-01603-0","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
We establish that, for any Tychonoff space X, at least one of the spaces \(C_p(X)\) and \(C_pC_p(X)\) has a dense subspace of countable pseudocharacter. Under MA, we give an example of a space X such that \(C_p(X)\) does not have a dense subspace of countable functional tightness. We also show that there exists a compact zero-dimensional space K such that \(C_p(K,\{0,1\})\) is exponentially separable while K is not a Sokolov space. For compact scattered spaces K of countable dispersion index, we show that \(C_p(K)\) has a dense exponentially separable subspace if and only if K is \(\omega \)-monolithic. Our results provide answers to several published open questions.
期刊介绍:
Acta Mathematica Hungarica is devoted to publishing research articles of top quality in all areas of pure and applied mathematics as well as in theoretical computer science. The journal is published yearly in three volumes (two issues per volume, in total 6 issues) in both print and electronic formats. Acta Mathematica Hungarica (formerly Acta Mathematica Academiae Scientiarum Hungaricae) was founded in 1950 by the Hungarian Academy of Sciences.