{"title":"弱和强可逆空间","authors":"Miloš S. Kurilić","doi":"10.1016/j.topol.2025.109596","DOIUrl":null,"url":null,"abstract":"<div><div>A topological space <span><math><mi>X</mi></math></span> is <em>reversible</em> iff each continuous bijection (condensation) <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>X</mi></math></span> is a homeomorphism; <em>weakly reversible</em> iff whenever <span><math><mi>Y</mi></math></span> is a space and there are condensations <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>Y</mi></math></span> and <span><math><mi>g</mi><mo>:</mo><mi>Y</mi><mo>→</mo><mi>X</mi></math></span>, there is a homeomorphism <span><math><mi>h</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>Y</mi></math></span>; <em>strongly reversible</em> iff each bijection <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>X</mi></math></span> is a homeomorphism. We show that the class of weakly reversible non-reversible spaces is disjoint from the class of sequential spaces in which each sequence has at most one limit (containing e.g. metrizable spaces). On the other hand, the class of strongly reversible topologies contains only discrete topologies, antidiscrete topologies and natural generalizations of the cofinite topology.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109596"},"PeriodicalIF":0.5000,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Weakly and strongly reversible spaces\",\"authors\":\"Miloš S. Kurilić\",\"doi\":\"10.1016/j.topol.2025.109596\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>A topological space <span><math><mi>X</mi></math></span> is <em>reversible</em> iff each continuous bijection (condensation) <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>X</mi></math></span> is a homeomorphism; <em>weakly reversible</em> iff whenever <span><math><mi>Y</mi></math></span> is a space and there are condensations <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>Y</mi></math></span> and <span><math><mi>g</mi><mo>:</mo><mi>Y</mi><mo>→</mo><mi>X</mi></math></span>, there is a homeomorphism <span><math><mi>h</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>Y</mi></math></span>; <em>strongly reversible</em> iff each bijection <span><math><mi>f</mi><mo>:</mo><mi>X</mi><mo>→</mo><mi>X</mi></math></span> is a homeomorphism. We show that the class of weakly reversible non-reversible spaces is disjoint from the class of sequential spaces in which each sequence has at most one limit (containing e.g. metrizable spaces). On the other hand, the class of strongly reversible topologies contains only discrete topologies, antidiscrete topologies and natural generalizations of the cofinite topology.</div></div>\",\"PeriodicalId\":51201,\"journal\":{\"name\":\"Topology and its Applications\",\"volume\":\"375 \",\"pages\":\"Article 109596\"},\"PeriodicalIF\":0.5000,\"publicationDate\":\"2025-09-12\",\"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/S0166864125003943\",\"RegionNum\":4,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Topology and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166864125003943","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
A topological space is reversible iff each continuous bijection (condensation) is a homeomorphism; weakly reversible iff whenever is a space and there are condensations and , there is a homeomorphism ; strongly reversible iff each bijection is a homeomorphism. We show that the class of weakly reversible non-reversible spaces is disjoint from the class of sequential spaces in which each sequence has at most one limit (containing e.g. metrizable spaces). On the other hand, the class of strongly reversible topologies contains only discrete topologies, antidiscrete topologies and natural generalizations of the cofinite topology.
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.