{"title":"无 (P5, HVN) 图形的色度数","authors":"Yian Xu","doi":"10.1007/s10255-024-1029-3","DOIUrl":null,"url":null,"abstract":"<div><p>Let <i>G</i> be a graph. We use <i>χ</i>(<i>G</i>) and <i>ω</i>(<i>G</i>) to denote the chromatic number and clique number of <i>G</i> respectively. A <i>P</i><sub>5</sub> is a path on 5 vertices, and an HVN is a <i>K</i><sub>4</sub> together with one more vertex which is adjacent to exactly two vertices of <i>K</i><sub>4</sub>. Combining with some known result, in this paper we show that if <i>G</i> is (<i>P</i><sub>5</sub>, <i>HVN</i>)-free, then <i>χ</i>(<i>G</i>) ≤ max{min{16, <i>ω</i>(<i>G</i>) + 3}, <i>ω</i>(<i>G</i>) + 1}. This upper bound is almost sharp.</p></div>","PeriodicalId":0,"journal":{"name":"","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"The Chromatic Number of (P5, HVN)-free Graphs\",\"authors\":\"Yian Xu\",\"doi\":\"10.1007/s10255-024-1029-3\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Let <i>G</i> be a graph. We use <i>χ</i>(<i>G</i>) and <i>ω</i>(<i>G</i>) to denote the chromatic number and clique number of <i>G</i> respectively. A <i>P</i><sub>5</sub> is a path on 5 vertices, and an HVN is a <i>K</i><sub>4</sub> together with one more vertex which is adjacent to exactly two vertices of <i>K</i><sub>4</sub>. Combining with some known result, in this paper we show that if <i>G</i> is (<i>P</i><sub>5</sub>, <i>HVN</i>)-free, then <i>χ</i>(<i>G</i>) ≤ max{min{16, <i>ω</i>(<i>G</i>) + 3}, <i>ω</i>(<i>G</i>) + 1}. This upper bound is almost sharp.</p></div>\",\"PeriodicalId\":0,\"journal\":{\"name\":\"\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0,\"publicationDate\":\"2024-11-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10255-024-1029-3\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s10255-024-1029-3","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Let G be a graph. We use χ(G) and ω(G) to denote the chromatic number and clique number of G respectively. A P5 is a path on 5 vertices, and an HVN is a K4 together with one more vertex which is adjacent to exactly two vertices of K4. Combining with some known result, in this paper we show that if G is (P5, HVN)-free, then χ(G) ≤ max{min{16, ω(G) + 3}, ω(G) + 1}. This upper bound is almost sharp.