{"title":"星形分支树和花束分支图的(Af)α-谱半径与其线性阶数的关系","authors":"Xueliang Li, Ruiling Zheng","doi":"10.1016/j.disc.2025.114734","DOIUrl":null,"url":null,"abstract":"<div><div>For a graph <em>G</em> and a vertex <em>v</em> of <em>G</em>, let <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow></msub><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span> be the graph obtained from <em>G</em> by linking the paths on <span><math><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> vertices to the vertex <em>v</em> of <em>G</em>, respectively. We denote by <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>(</mo><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>)</mo></math></span> (or <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> for short) the degree of the vertex <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> in <em>G</em>. Let <span><math><mi>f</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>></mo><mn>0</mn></math></span> be a real symmetric function in <em>x</em> and <em>y</em>. The function-weighted adjacency matrix <span><math><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>(</mo><mi>G</mi><mo>)</mo></math></span> of a graph <em>G</em> is a square matrix, where the <span><math><mo>(</mo><mi>i</mi><mo>,</mo><mi>j</mi><mo>)</mo></math></span>-entry is equal to <span><math><mi>f</mi><mo>(</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>)</mo></math></span> if the vertices <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>j</mi></mrow></msub></math></span> are adjacent and 0 otherwise, in which <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> is the degree of the vertex <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. In <span><span>[22]</span></span>, Shan and Liu showed that the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></mrow></math></span> will increase according to the shortlex ordering of <span><math><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span>. However, we find some mistakes in their proof. In this paper, we will correct their proof, and moreover, extend their results from the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius to the <span><math><msub><mrow><mo>(</mo><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>)</mo></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius. In addition, let <span><math><msubsup><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow><mrow><mi>c</mi></mrow></msubsup><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span> be the graph obtained from <em>G</em> by identifying a vertex from each of the cycles on <span><math><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> vertices and the vertex <em>v</em> of <em>G</em>, respectively. We will show that the <span><math><msub><mrow><mo>(</mo><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>)</mo></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><msubsup><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow><mrow><mi>c</mi></mrow></msubsup><mrow><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></mrow></math></span> will decrease according to the majorization ordering of <span><math><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span>.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 1","pages":"Article 114734"},"PeriodicalIF":0.7000,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On the relationship between (Af)α-spectral radii of graphs with starlike branch tree or bouquet branch graph and its linearly order\",\"authors\":\"Xueliang Li, Ruiling Zheng\",\"doi\":\"10.1016/j.disc.2025.114734\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>For a graph <em>G</em> and a vertex <em>v</em> of <em>G</em>, let <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow></msub><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span> be the graph obtained from <em>G</em> by linking the paths on <span><math><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> vertices to the vertex <em>v</em> of <em>G</em>, respectively. We denote by <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>(</mo><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>)</mo></math></span> (or <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> for short) the degree of the vertex <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> in <em>G</em>. Let <span><math><mi>f</mi><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo><mo>></mo><mn>0</mn></math></span> be a real symmetric function in <em>x</em> and <em>y</em>. The function-weighted adjacency matrix <span><math><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>(</mo><mi>G</mi><mo>)</mo></math></span> of a graph <em>G</em> is a square matrix, where the <span><math><mo>(</mo><mi>i</mi><mo>,</mo><mi>j</mi><mo>)</mo></math></span>-entry is equal to <span><math><mi>f</mi><mo>(</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>)</mo></math></span> if the vertices <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>j</mi></mrow></msub></math></span> are adjacent and 0 otherwise, in which <span><math><msub><mrow><mi>d</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> is the degree of the vertex <span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. In <span><span>[22]</span></span>, Shan and Liu showed that the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow></msub><mrow><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></mrow></math></span> will increase according to the shortlex ordering of <span><math><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span>. However, we find some mistakes in their proof. In this paper, we will correct their proof, and moreover, extend their results from the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius to the <span><math><msub><mrow><mo>(</mo><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>)</mo></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius. In addition, let <span><math><msubsup><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow><mrow><mi>c</mi></mrow></msubsup><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span> be the graph obtained from <em>G</em> by identifying a vertex from each of the cycles on <span><math><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> vertices and the vertex <em>v</em> of <em>G</em>, respectively. We will show that the <span><math><msub><mrow><mo>(</mo><msup><mrow><mi>A</mi></mrow><mrow><mi>f</mi></mrow></msup><mo>)</mo></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><msubsup><mrow><mi>G</mi></mrow><mrow><mi>v</mi></mrow><mrow><mi>c</mi></mrow></msubsup><mrow><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></mrow></math></span> will decrease according to the majorization ordering of <span><math><mo>(</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>n</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>)</mo></math></span>.</div></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"349 1\",\"pages\":\"Article 114734\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2025-08-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0012365X25003425\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25003425","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
On the relationship between (Af)α-spectral radii of graphs with starlike branch tree or bouquet branch graph and its linearly order
For a graph G and a vertex v of G, let be the graph obtained from G by linking the paths on vertices to the vertex v of G, respectively. We denote by (or for short) the degree of the vertex in G. Let be a real symmetric function in x and y. The function-weighted adjacency matrix of a graph G is a square matrix, where the -entry is equal to if the vertices and are adjacent and 0 otherwise, in which is the degree of the vertex . In [22], Shan and Liu showed that the -spectral radius of will increase according to the shortlex ordering of . However, we find some mistakes in their proof. In this paper, we will correct their proof, and moreover, extend their results from the -spectral radius to the -spectral radius. In addition, let be the graph obtained from G by identifying a vertex from each of the cycles on vertices and the vertex v of G, respectively. We will show that the -spectral radius of will decrease according to the majorization ordering of .
期刊介绍:
Discrete Mathematics provides a common forum for significant research in many areas of discrete mathematics and combinatorics. Among the fields covered by Discrete Mathematics are graph and hypergraph theory, enumeration, coding theory, block designs, the combinatorics of partially ordered sets, extremal set theory, matroid theory, algebraic combinatorics, discrete geometry, matrices, and discrete probability theory.
Items in the journal include research articles (Contributions or Notes, depending on length) and survey/expository articles (Perspectives). Efforts are made to process the submission of Notes (short articles) quickly. The Perspectives section features expository articles accessible to a broad audience that cast new light or present unifying points of view on well-known or insufficiently-known topics.