{"title":"On partial knots for symmetric unions","authors":"Christoph Lamm , Toshifumi Tanaka","doi":"10.1016/j.topol.2025.109593","DOIUrl":null,"url":null,"abstract":"<div><div>In this paper, we show that the partial knot of a 2-bridge ribbon knot is a 2-bridge knot. In particular, we determine the sets of partial knots for all 2-bridge ribbon knots up to 10 crossings, except for 10<sub>3</sub>. Concerning composite symmetric unions, we show that there exists an infinite family of prime knots <span><math><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>}</mo></math></span> such that <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>♯</mo><mo>−</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span> has at least two partial knots and we obtain symmetric union presentations for a certain family of nonsymmetric composite ribbon knots one of which was a potential counterexample to the question which asks if every ribbon knot is a symmetric union. Finally, we show that a partial knot of a symmetric union presentation with one twist region of the Kinoshita-Terasaka knot has trivial Jones polynomial.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109593"},"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/S0166864125003918","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
In this paper, we show that the partial knot of a 2-bridge ribbon knot is a 2-bridge knot. In particular, we determine the sets of partial knots for all 2-bridge ribbon knots up to 10 crossings, except for 103. Concerning composite symmetric unions, we show that there exists an infinite family of prime knots such that has at least two partial knots and we obtain symmetric union presentations for a certain family of nonsymmetric composite ribbon knots one of which was a potential counterexample to the question which asks if every ribbon knot is a symmetric union. Finally, we show that a partial knot of a symmetric union presentation with one twist region of the Kinoshita-Terasaka knot has trivial Jones polynomial.
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.