{"title":"Independence Number and Maximal Chromatic Polynomials of Connected Graphs","authors":"Shude Long, Junliang Cai","doi":"10.1007/s00373-024-02824-2","DOIUrl":null,"url":null,"abstract":"<p>Let <span>\\({\\mathcal {C}}_{k}(n)\\)</span> denote the family of all connected graphs of order <i>n</i> with chromatic number <i>k</i>. In this paper we show that the conjecture proposed by Tomescu which if <span>\\(x\\ge k\\ge 4\\)</span> and <span>\\(G\\in {\\mathcal {C}}_{k}(n)\\)</span>, then </p><span>$$\\begin{aligned} P(G,x)\\le (x)_{k} (x-1)^{n-k} \\end{aligned}$$</span><p>holds under the additional condition that <i>G</i> has an independent cut-set <i>T</i> of size at most 2 such that the number of components in <span>\\(G{\\setminus } T\\)</span> is equal to the independence number of <i>G</i>.</p>","PeriodicalId":12811,"journal":{"name":"Graphs and Combinatorics","volume":null,"pages":null},"PeriodicalIF":0.6000,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Graphs and Combinatorics","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1007/s00373-024-02824-2","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
Let \({\mathcal {C}}_{k}(n)\) denote the family of all connected graphs of order n with chromatic number k. In this paper we show that the conjecture proposed by Tomescu which if \(x\ge k\ge 4\) and \(G\in {\mathcal {C}}_{k}(n)\), then
holds under the additional condition that G has an independent cut-set T of size at most 2 such that the number of components in \(G{\setminus } T\) is equal to the independence number of G.
让 \({\mathcal {C}}_{k}(n)\) 表示色度数为 k 的 n 阶所有连通图的族。 本文将证明 Tomescu 提出的猜想,即如果 \(x\ge k\ge 4\) and\(G\in {\mathcal {C}}_{k}(n)\), then $$\begin{aligned}P(G,x)\le (x)_{k}(x-1)^{n-k}\end{aligned}$$holds under the additional condition that G has an independent cut-set T of size at most 2 such that the number of components in \(G{\setminus } T\) is equal to the independence number of G.
期刊介绍:
Graphs and Combinatorics is an international journal devoted to research concerning all aspects of combinatorial mathematics. In addition to original research papers, the journal also features survey articles from authors invited by the editorial board.