{"title":"路径幂的近自同构","authors":"Shoushuang Chen, Shikun Ou","doi":"10.1016/j.dam.2025.09.015","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><mi>G</mi></math></span> be a connected graph with vertex set <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>, and <span><math><mi>f</mi></math></span> a permutation on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. Define <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>|</mo><mi>d</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>−</mo><mi>d</mi><mrow><mo>(</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mo>,</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>)</mo></mrow><mo>)</mo></mrow><mo>|</mo></mrow></mrow></math></span> and <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><mo>∑</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow></mrow></math></span>, where the sum is taken over all unordered pairs <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> of distinct vertices of <span><math><mi>G</mi></math></span>. Denote by <span><math><mrow><mi>π</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> the smallest positive value of <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> among all permutations on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. A permutation <span><math><mi>f</mi></math></span> on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> is called a <em>near automorphism</em> of <span><math><mi>G</mi></math></span> if <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><mi>π</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. The <span><math><mi>k</mi></math></span>th power of <span><math><mi>G</mi></math></span>, written as <span><math><msup><mrow><mi>G</mi></mrow><mrow><mi>k</mi></mrow></msup></math></span>, also has <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> as vertex set, but <span><math><mi>x</mi></math></span> and <span><math><mi>y</mi></math></span> are adjacent in <span><math><msup><mrow><mi>G</mi></mrow><mrow><mi>k</mi></mrow></msup></math></span> whenever <span><math><mrow><mi>d</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>≤</mo><mi>k</mi></mrow></math></span> in <span><math><mi>G</mi></math></span>. The near automorphisms of the path <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> and its square <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> were described in Aitken (1999) and Wong et al. (2023), respectively. In this paper, we give the value of <span><math><mrow><mi>π</mi><mrow><mo>(</mo><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>k</mi></mrow></msubsup><mo>)</mo></mrow></mrow></math></span>, and determine the near automorphisms of <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>k</mi></mrow></msubsup></math></span> when <span><math><mrow><mn>3</mn><mo>≤</mo><mi>k</mi><mo>≤</mo><mi>n</mi><mo>−</mo><mn>2</mn></mrow></math></span>.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"379 ","pages":"Pages 482-499"},"PeriodicalIF":1.0000,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Near automorphisms of powers of a path\",\"authors\":\"Shoushuang Chen, Shikun Ou\",\"doi\":\"10.1016/j.dam.2025.09.015\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <span><math><mi>G</mi></math></span> be a connected graph with vertex set <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>, and <span><math><mi>f</mi></math></span> a permutation on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. Define <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>|</mo><mi>d</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>−</mo><mi>d</mi><mrow><mo>(</mo><mi>f</mi><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mo>,</mo><mi>f</mi><mrow><mo>(</mo><mi>y</mi><mo>)</mo></mrow><mo>)</mo></mrow><mo>|</mo></mrow></mrow></math></span> and <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><mo>∑</mo><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow></mrow></math></span>, where the sum is taken over all unordered pairs <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> of distinct vertices of <span><math><mi>G</mi></math></span>. Denote by <span><math><mrow><mi>π</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> the smallest positive value of <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> among all permutations on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. A permutation <span><math><mi>f</mi></math></span> on <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> is called a <em>near automorphism</em> of <span><math><mi>G</mi></math></span> if <span><math><mrow><msub><mrow><mi>δ</mi></mrow><mrow><mi>f</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><mi>π</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. The <span><math><mi>k</mi></math></span>th power of <span><math><mi>G</mi></math></span>, written as <span><math><msup><mrow><mi>G</mi></mrow><mrow><mi>k</mi></mrow></msup></math></span>, also has <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> as vertex set, but <span><math><mi>x</mi></math></span> and <span><math><mi>y</mi></math></span> are adjacent in <span><math><msup><mrow><mi>G</mi></mrow><mrow><mi>k</mi></mrow></msup></math></span> whenever <span><math><mrow><mi>d</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>≤</mo><mi>k</mi></mrow></math></span> in <span><math><mi>G</mi></math></span>. The near automorphisms of the path <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> and its square <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msubsup></math></span> were described in Aitken (1999) and Wong et al. (2023), respectively. In this paper, we give the value of <span><math><mrow><mi>π</mi><mrow><mo>(</mo><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>k</mi></mrow></msubsup><mo>)</mo></mrow></mrow></math></span>, and determine the near automorphisms of <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>k</mi></mrow></msubsup></math></span> when <span><math><mrow><mn>3</mn><mo>≤</mo><mi>k</mi><mo>≤</mo><mi>n</mi><mo>−</mo><mn>2</mn></mrow></math></span>.</div></div>\",\"PeriodicalId\":50573,\"journal\":{\"name\":\"Discrete Applied Mathematics\",\"volume\":\"379 \",\"pages\":\"Pages 482-499\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2025-09-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Applied Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166218X25005414\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS, APPLIED\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Applied Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166218X25005414","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
摘要
设G是顶点集V(G)的连通图,f是V(G)上的一个置换。定义δf(x,y)=|d(x,y)−d(f(x),f(y))|和δf(G)=∑δf(x,y),其中对G上不同顶点的所有无序对x,y求和,用π(G)表示V(G)上所有排列中δf(G)的最小正值。如果δf(G)=π(G),则f在V(G)上的排列称为G的近自同构。G的k次幂,写为Gk,也有V(G)作为顶点集,但是当G中的d(x,y)≤k时,x和y在Gk中相邻。路径Pn及其平方Pn2的近自同态分别在Aitken(1999)和Wong et al.(2023)中描述。本文给出了π(Pnk)的值,并确定了Pnk在3≤k≤n−2时的近自同构。
Let be a connected graph with vertex set , and a permutation on . Define and , where the sum is taken over all unordered pairs of distinct vertices of . Denote by the smallest positive value of among all permutations on . A permutation on is called a near automorphism of if . The th power of , written as , also has as vertex set, but and are adjacent in whenever in . The near automorphisms of the path and its square were described in Aitken (1999) and Wong et al. (2023), respectively. In this paper, we give the value of , and determine the near automorphisms of when .
期刊介绍:
The aim of Discrete Applied Mathematics is to bring together research papers in different areas of algorithmic and applicable discrete mathematics as well as applications of combinatorial mathematics to informatics and various areas of science and technology. Contributions presented to the journal can be research papers, short notes, surveys, and possibly research problems. The "Communications" section will be devoted to the fastest possible publication of recent research results that are checked and recommended for publication by a member of the Editorial Board. The journal will also publish a limited number of book announcements as well as proceedings of conferences. These proceedings will be fully refereed and adhere to the normal standards of the journal.
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