向量空间的s-几乎t相交族

IF 0.7 3区 数学 Q2 MATHEMATICS
Lijun Ji , Dehai Liu , Kaishun Wang , Tian Yao , Shuhui Yu
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We say <span><math><mi>F</mi></math></span> is <em>s</em>-almost <em>t</em>-intersecting if <span><math><mrow><mo>|</mo><mrow><mo>{</mo><mi>F</mi><mo>∈</mo><mi>F</mi><mo>:</mo><mi>dim</mi><mo>⁡</mo><mo>(</mo><mi>F</mi><mo>∩</mo><msup><mrow><mi>F</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>)</mo><mo>&lt;</mo><mi>t</mi><mo>}</mo></mrow><mo>|</mo></mrow><mo>≤</mo><mi>s</mi></math></span> for any <span><math><msup><mrow><mi>F</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>∈</mo><mi>F</mi></math></span>. In this paper, we prove that <em>s</em>-almost <em>t</em>-intersecting families with maximum size are <em>t</em>-intersecting. We also consider <em>s</em>-almost <em>t</em>-intersecting families which are not <em>t</em>-intersecting, and characterize such families with maximum size for <span><math><mo>(</mo><mi>s</mi><mo>,</mo><mi>t</mi><mo>)</mo><mo>≠</mo><mo>(</mo><mn>1</mn><mo>,</mo><mn>1</mn><mo>)</mo></math></span> and <span><math><mi>k</mi><mo>≥</mo><mi>t</mi><mo>+</mo><mn>2</mn></math></span>. The results for 1-almost 1-intersecting families provided by Shan and Zhou are generalized.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 1","pages":"Article 114661"},"PeriodicalIF":0.7000,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"s-almost t-intersecting families for vector spaces\",\"authors\":\"Lijun Ji ,&nbsp;Dehai Liu ,&nbsp;Kaishun Wang ,&nbsp;Tian Yao ,&nbsp;Shuhui Yu\",\"doi\":\"10.1016/j.disc.2025.114661\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <em>V</em> be a finite dimensional vector space over a finite field, and <span><math><mi>F</mi></math></span> a family consisting of <em>k</em>-subspaces of <em>V</em>. 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The results for 1-almost 1-intersecting families provided by Shan and Zhou are generalized.</div></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"349 1\",\"pages\":\"Article 114661\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2025-07-07\",\"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/S0012365X25002699\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25002699","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

摘要

设V是有限域上的有限维向量空间,F是由V的k个子空间组成的族。对于任意F,F '∈F,如果dim (F∩F ')≥t,族F称为t相交。我们说,如果|{F∈F:dim (F∩F ')<t}|≤s,对于任何F '∈F, F是s-概t相交。本文证明了具有最大大小的s-几乎t相交族是t相交的。我们还考虑了非t相交的s-几乎t相交族,并刻画了这类族在(s,t)≠(1,1)和k≥t+2时的最大尺寸。推广了Shan和Zhou给出的关于1-几乎1相交族的结果。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
s-almost t-intersecting families for vector spaces
Let V be a finite dimensional vector space over a finite field, and F a family consisting of k-subspaces of V. The family F is called t-intersecting if dim(FF)t for any F,FF. We say F is s-almost t-intersecting if |{FF:dim(FF)<t}|s for any FF. In this paper, we prove that s-almost t-intersecting families with maximum size are t-intersecting. We also consider s-almost t-intersecting families which are not t-intersecting, and characterize such families with maximum size for (s,t)(1,1) and kt+2. The results for 1-almost 1-intersecting families provided by Shan and Zhou are generalized.
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来源期刊
Discrete Mathematics
Discrete Mathematics 数学-数学
CiteScore
1.50
自引率
12.50%
发文量
424
审稿时长
6 months
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. Items in the journal include research articles (Contributions or Notes, depending on length) and survey/expository articles (Perspectives). Efforts are made to process the submission of Notes (short articles) quickly. The Perspectives section features expository articles accessible to a broad audience that cast new light or present unifying points of view on well-known or insufficiently-known topics.
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