{"title":"在可数序数上的群","authors":"Stepan Milošević , Stevo Todorčević","doi":"10.1016/j.topol.2025.109480","DOIUrl":null,"url":null,"abstract":"<div><div>This paper deals with topological groups constructed from characteristics of walks on countable ordinals. We introduce two groups, constructed from <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and show they are both Fréchet, non-metrizable and that the topological group constructed from <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> has the maximal Tukey type among topological groups of character <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. We also consider the group associated with <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> introduced in [12] and show that under some set-theoretic assumptions the group does not have the maximal Tukey type.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"373 ","pages":"Article 109480"},"PeriodicalIF":0.5000,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Groups from walks on countable ordinals\",\"authors\":\"Stepan Milošević , Stevo Todorčević\",\"doi\":\"10.1016/j.topol.2025.109480\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>This paper deals with topological groups constructed from characteristics of walks on countable ordinals. We introduce two groups, constructed from <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and show they are both Fréchet, non-metrizable and that the topological group constructed from <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> has the maximal Tukey type among topological groups of character <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. We also consider the group associated with <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> introduced in [12] and show that under some set-theoretic assumptions the group does not have the maximal Tukey type.</div></div>\",\"PeriodicalId\":51201,\"journal\":{\"name\":\"Topology and its Applications\",\"volume\":\"373 \",\"pages\":\"Article 109480\"},\"PeriodicalIF\":0.5000,\"publicationDate\":\"2025-06-13\",\"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/S0166864125002780\",\"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/S0166864125002780","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
This paper deals with topological groups constructed from characteristics of walks on countable ordinals. We introduce two groups, constructed from and , and show they are both Fréchet, non-metrizable and that the topological group constructed from has the maximal Tukey type among topological groups of character . We also consider the group associated with introduced in [12] and show that under some set-theoretic assumptions the group does not have the maximal Tukey type.
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.