{"title":"路径和簇的广义图兰问题","authors":"Xiaona Fang, Xiutao Zhu, Yaojun Chen","doi":"arxiv-2409.10129","DOIUrl":null,"url":null,"abstract":"Let $\\mathcal{H}$ be a family of graphs. The generalized Tur\\'an number\n$ex(n, K_r, \\mathcal{H})$ is the maximum number of copies of the clique $K_r$\nin any $n$-vertex $\\mathcal{H}$-free graph. In this paper, we determine the\nvalue of $ex(n, K_r, \\{P_k, K_m \\} )$ for sufficiently large $n$ with an\nexceptional case, and characterize all corresponding extremal graphs, which\ngeneralizes and strengthens the results of Katona and Xiao [EJC, 2024] on\n$ex(n, K_2, \\{P_k, K_m \\} )$. For the exceptional case, we obtain a tight upper\nbound for $ex(n, K_r, \\{P_k, K_m \\} )$ that confirms a conjecture on $ex(n,\nK_2, \\{P_k, K_m \\} )$ posed by Katona and Xiao.","PeriodicalId":501407,"journal":{"name":"arXiv - MATH - Combinatorics","volume":"117 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Generalized Turán problem for a path and a clique\",\"authors\":\"Xiaona Fang, Xiutao Zhu, Yaojun Chen\",\"doi\":\"arxiv-2409.10129\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Let $\\\\mathcal{H}$ be a family of graphs. The generalized Tur\\\\'an number\\n$ex(n, K_r, \\\\mathcal{H})$ is the maximum number of copies of the clique $K_r$\\nin any $n$-vertex $\\\\mathcal{H}$-free graph. In this paper, we determine the\\nvalue of $ex(n, K_r, \\\\{P_k, K_m \\\\} )$ for sufficiently large $n$ with an\\nexceptional case, and characterize all corresponding extremal graphs, which\\ngeneralizes and strengthens the results of Katona and Xiao [EJC, 2024] on\\n$ex(n, K_2, \\\\{P_k, K_m \\\\} )$. For the exceptional case, we obtain a tight upper\\nbound for $ex(n, K_r, \\\\{P_k, K_m \\\\} )$ that confirms a conjecture on $ex(n,\\nK_2, \\\\{P_k, K_m \\\\} )$ posed by Katona and Xiao.\",\"PeriodicalId\":501407,\"journal\":{\"name\":\"arXiv - MATH - Combinatorics\",\"volume\":\"117 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-16\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - MATH - Combinatorics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2409.10129\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - MATH - Combinatorics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.10129","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Let $\mathcal{H}$ be a family of graphs. The generalized Tur\'an number
$ex(n, K_r, \mathcal{H})$ is the maximum number of copies of the clique $K_r$
in any $n$-vertex $\mathcal{H}$-free graph. In this paper, we determine the
value of $ex(n, K_r, \{P_k, K_m \} )$ for sufficiently large $n$ with an
exceptional case, and characterize all corresponding extremal graphs, which
generalizes and strengthens the results of Katona and Xiao [EJC, 2024] on
$ex(n, K_2, \{P_k, K_m \} )$. For the exceptional case, we obtain a tight upper
bound for $ex(n, K_r, \{P_k, K_m \} )$ that confirms a conjecture on $ex(n,
K_2, \{P_k, K_m \} )$ posed by Katona and Xiao.