{"title":"馀度Turán紧环的密度减去一条边","authors":"Simón Piga, Marcelo Sales, Bjarne Schülke","doi":"10.1017/s0963548323000196","DOIUrl":null,"url":null,"abstract":"<p>Given <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$\\alpha \\gt 0$</span></span></img></span></span> and an integer <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$\\ell \\geq 5$</span></span></img></span></span>, we prove that every sufficiently large <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$3$</span></span></img></span></span>-uniform hypergraph <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$H$</span></span></img></span></span> on <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline5.png\"><span data-mathjax-type=\"texmath\"><span>$n$</span></span></img></span></span> vertices in which every two vertices are contained in at least <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$\\alpha n$</span></span></img></span></span> edges contains a copy of <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline7.png\"><span data-mathjax-type=\"texmath\"><span>$C_\\ell ^{-}$</span></span></img></span></span>, a tight cycle on <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline8.png\"><span data-mathjax-type=\"texmath\"><span>$\\ell$</span></span></img></span></span> vertices minus one edge. This improves a previous result by Balogh, Clemen, and Lidický.</p>","PeriodicalId":10503,"journal":{"name":"Combinatorics, Probability and Computing","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"The codegree Turán density of tight cycles minus one edge\",\"authors\":\"Simón Piga, Marcelo Sales, Bjarne Schülke\",\"doi\":\"10.1017/s0963548323000196\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Given <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline1.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$\\\\alpha \\\\gt 0$</span></span></img></span></span> and an integer <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline2.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$\\\\ell \\\\geq 5$</span></span></img></span></span>, we prove that every sufficiently large <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline3.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$3$</span></span></img></span></span>-uniform hypergraph <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline4.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$H$</span></span></img></span></span> on <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline5.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$n$</span></span></img></span></span> vertices in which every two vertices are contained in at least <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline6.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$\\\\alpha n$</span></span></img></span></span> edges contains a copy of <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline7.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$C_\\\\ell ^{-}$</span></span></img></span></span>, a tight cycle on <span><span><img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231006153727984-0672:S0963548323000196:S0963548323000196_inline8.png\\\"><span data-mathjax-type=\\\"texmath\\\"><span>$\\\\ell$</span></span></img></span></span> vertices minus one edge. This improves a previous result by Balogh, Clemen, and Lidický.</p>\",\"PeriodicalId\":10503,\"journal\":{\"name\":\"Combinatorics, Probability and Computing\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2023-07-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Combinatorics, Probability and Computing\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1017/s0963548323000196\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Combinatorics, Probability and Computing","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1017/s0963548323000196","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
The codegree Turán density of tight cycles minus one edge
Given $\alpha \gt 0$ and an integer $\ell \geq 5$, we prove that every sufficiently large $3$-uniform hypergraph $H$ on $n$ vertices in which every two vertices are contained in at least $\alpha n$ edges contains a copy of $C_\ell ^{-}$, a tight cycle on $\ell$ vertices minus one edge. This improves a previous result by Balogh, Clemen, and Lidický.