Kenneth L. Baker , Yasuyuki Miyazawa , Kimihiko Motegi
{"title":"Asymptotic behavior of unknotting numbers of links in a twist family","authors":"Kenneth L. Baker , Yasuyuki Miyazawa , Kimihiko Motegi","doi":"10.1016/j.topol.2025.109350","DOIUrl":null,"url":null,"abstract":"<div><div>By twisting a given link <em>L</em> along an unknotted circle <em>c</em>, we obtain an infinite family of links <span><math><mo>{</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>}</mo></math></span>. We introduce “stable unknotting number” which describes the asymptotic behavior of unknotting numbers of links in the twist family. We show the stable unknotting number for any twist family of links depends only on the winding number of <em>L</em> about <em>c</em> (the minimum geometric intersection number of <em>L</em> with a Seifert surface of <em>c</em>) and is independent of the wrapping number of <em>L</em> about <em>c</em> (the minimum geometric intersection number of <em>L</em> with a disk bounded by <em>c</em>). Thus there are twist families for which the discrepancy between the wrapping number and the stable unknotting number is arbitrarily large.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"367 ","pages":"Article 109350"},"PeriodicalIF":0.6000,"publicationDate":"2025-03-18","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/S0166864125001488","RegionNum":4,"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
By twisting a given link L along an unknotted circle c, we obtain an infinite family of links . We introduce “stable unknotting number” which describes the asymptotic behavior of unknotting numbers of links in the twist family. We show the stable unknotting number for any twist family of links depends only on the winding number of L about c (the minimum geometric intersection number of L with a Seifert surface of c) and is independent of the wrapping number of L about c (the minimum geometric intersection number of L with a disk bounded by c). Thus there are twist families for which the discrepancy between the wrapping number and the stable unknotting number is arbitrarily large.
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.