Xiaoxue Hu , Jiangxu Kong , Weifan Wang , Wanshun Yang
{"title":"A note on the r-hued coloring of planar graphs","authors":"Xiaoxue Hu , Jiangxu Kong , Weifan Wang , Wanshun Yang","doi":"10.1016/j.disc.2025.114829","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><mi>r</mi><mo>≥</mo><mn>1</mn></math></span> be an integer. The <em>r</em>-hued chromatic number <span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>(</mo><mi>G</mi><mo>)</mo></math></span> of a graph <em>G</em> is the smallest integer <em>k</em> for which <em>G</em> admits a proper <em>k</em>-coloring for the vertices such that the number of colors used in the neighborhood of every vertex <em>v</em> is at least <span><math><mi>min</mi><mo></mo><mo>{</mo><msub><mrow><mi>d</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>(</mo><mi>v</mi><mo>)</mo><mo>,</mo><mi>r</mi><mo>}</mo></math></span>. Let <em>G</em> be a planar graph and <span><math><mi>r</mi><mo>≥</mo><mn>8</mn></math></span>. In this paper we show that <span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>(</mo><mi>G</mi><mo>)</mo><mo>≤</mo><mn>2</mn><mi>r</mi><mo>+</mo><mn>8</mn></math></span>, which improves a result by Song and Lai (2018) <span><span>[12]</span></span> that <span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>(</mo><mi>G</mi><mo>)</mo><mo>≤</mo><mn>2</mn><mi>r</mi><mo>+</mo><mn>16</mn></math></span>.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 2","pages":"Article 114829"},"PeriodicalIF":0.7000,"publicationDate":"2025-10-08","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/S0012365X25004376","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Let be an integer. The r-hued chromatic number of a graph G is the smallest integer k for which G admits a proper k-coloring for the vertices such that the number of colors used in the neighborhood of every vertex v is at least . Let G be a planar graph and . In this paper we show that , which improves a result by Song and Lai (2018) [12] that .
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.
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