{"title":"On m-Closure of Ideals in LBI-Subalgebras","authors":"Masoumeh Etebar, Mehdi Parsinia, Alireza Salehi","doi":"10.1007/s41980-024-00884-x","DOIUrl":null,"url":null,"abstract":"<p>Let <i>C</i>(<i>X</i>) be the ring of all continuous real-valued functions on a completely regular Hausdorff space <i>X</i>. A subalgebra <i>A</i>(<i>X</i>) of <i>C</i>(<i>X</i>) is said to be closed under local bounded inversion, briefly an <i>LBI</i>-subalgebra, if for every function <i>f</i> in <i>A</i>(<i>X</i>) that is bounded away from zero on a cozero-set <i>E</i> of <i>X</i>, there exists <span>\\(g\\in A(X)\\)</span> such that <span>\\(fg|_E=1\\)</span>. In this paper, for an <i>LBI</i>-subalgebra <i>A</i>(<i>X</i>) the compactification <span>\\(\\beta _AX\\)</span> of <i>X</i> which is homeomorphic with the structure space of <i>A</i>(<i>X</i>) is investigated. Some properties of <span>\\(\\beta _AX\\)</span> similar to the counterparts in <span>\\(\\beta X\\)</span> and some main differences between these compactifications are given. Using the compactification <span>\\(\\beta _AX\\)</span>, we establish an <i>m</i>-closure formula for ideals in a class of <i>LBI</i>-subalgebras which provides a generalization of <i>m</i>-closure of ideals in intermediate algebras of <i>C</i>(<i>X</i>) and <span>\\(C_c(X)\\)</span>. We also investigate a characterization of <span>\\(\\beta \\)</span>-ideals for <i>LBI</i>-subalgebras from which it turns out that <i>m</i>-closed ideals coincide with <span>\\(\\beta \\)</span>-ideals in that class of <i>LBI</i>-subalgebras.</p>","PeriodicalId":9395,"journal":{"name":"Bulletin of The Iranian Mathematical Society","volume":null,"pages":null},"PeriodicalIF":0.7000,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of The Iranian Mathematical Society","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1007/s41980-024-00884-x","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Let C(X) be the ring of all continuous real-valued functions on a completely regular Hausdorff space X. A subalgebra A(X) of C(X) is said to be closed under local bounded inversion, briefly an LBI-subalgebra, if for every function f in A(X) that is bounded away from zero on a cozero-set E of X, there exists \(g\in A(X)\) such that \(fg|_E=1\). In this paper, for an LBI-subalgebra A(X) the compactification \(\beta _AX\) of X which is homeomorphic with the structure space of A(X) is investigated. Some properties of \(\beta _AX\) similar to the counterparts in \(\beta X\) and some main differences between these compactifications are given. Using the compactification \(\beta _AX\), we establish an m-closure formula for ideals in a class of LBI-subalgebras which provides a generalization of m-closure of ideals in intermediate algebras of C(X) and \(C_c(X)\). We also investigate a characterization of \(\beta \)-ideals for LBI-subalgebras from which it turns out that m-closed ideals coincide with \(\beta \)-ideals in that class of LBI-subalgebras.
期刊介绍:
The Bulletin of the Iranian Mathematical Society (BIMS) publishes original research papers as well as survey articles on a variety of hot topics from distinguished mathematicians. Research papers presented comprise of innovative contributions while expository survey articles feature important results that appeal to a broad audience. Articles are expected to address active research topics and are required to cite existing (including recent) relevant literature appropriately. Papers are critically reviewed on the basis of quality in its exposition, brevity, potential applications, motivation, value and originality of the results. The BIMS takes a high standard policy against any type plagiarism. The editorial board is devoted to solicit expert referees for a fast and unbiased review process.