{"title":"弱组合的多样性和相交定理","authors":"Cheng Yeaw Ku , Kok Bin Wong","doi":"10.1016/j.disc.2024.114250","DOIUrl":null,"url":null,"abstract":"<div><p>Let <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> be the set of non-negative integers, and let <span><math><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span> denote the set of all weak compositions of <em>n</em> with <em>k</em> parts, i.e., <span><math><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo><mo>=</mo><mo>{</mo><mo>(</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>)</mo><mo>∈</mo><msubsup><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow><mrow><mi>k</mi></mrow></msubsup><mspace></mspace><mo>:</mo><mspace></mspace><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mo>⋯</mo><mo>+</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>=</mo><mi>n</mi><mo>}</mo></math></span>. For any element <span><math><mi>u</mi><mo>=</mo><mo>(</mo><msub><mrow><mi>u</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>u</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>u</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>)</mo><mo>∈</mo><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span>, denote its <em>i</em>th-coordinate by <span><math><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo></math></span>, i.e., <span><math><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>=</mo><msub><mrow><mi>u</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. A family <span><math><mi>A</mi><mo>⊆</mo><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span> is said to be <em>t</em>-intersecting if <span><math><mo>|</mo><mo>{</mo><mi>i</mi><mspace></mspace><mo>:</mo><mspace></mspace><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>=</mo><mi>v</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>}</mo><mo>|</mo><mo>≥</mo><mi>t</mi></math></span> for all <span><math><mi>u</mi><mo>,</mo><mi>v</mi><mo>∈</mo><mi>A</mi></math></span>. In this paper, we consider the diversity and other intersecting theorems for weak compositions.</p></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"348 2","pages":"Article 114250"},"PeriodicalIF":0.7000,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Diversity and intersecting theorems for weak compositions\",\"authors\":\"Cheng Yeaw Ku , Kok Bin Wong\",\"doi\":\"10.1016/j.disc.2024.114250\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Let <span><math><msub><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> be the set of non-negative integers, and let <span><math><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span> denote the set of all weak compositions of <em>n</em> with <em>k</em> parts, i.e., <span><math><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo><mo>=</mo><mo>{</mo><mo>(</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>)</mo><mo>∈</mo><msubsup><mrow><mi>N</mi></mrow><mrow><mn>0</mn></mrow><mrow><mi>k</mi></mrow></msubsup><mspace></mspace><mo>:</mo><mspace></mspace><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mo>⋯</mo><mo>+</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>=</mo><mi>n</mi><mo>}</mo></math></span>. For any element <span><math><mi>u</mi><mo>=</mo><mo>(</mo><msub><mrow><mi>u</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>u</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>u</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>)</mo><mo>∈</mo><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span>, denote its <em>i</em>th-coordinate by <span><math><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo></math></span>, i.e., <span><math><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>=</mo><msub><mrow><mi>u</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. A family <span><math><mi>A</mi><mo>⊆</mo><mi>P</mi><mo>(</mo><mi>n</mi><mo>,</mo><mi>k</mi><mo>)</mo></math></span> is said to be <em>t</em>-intersecting if <span><math><mo>|</mo><mo>{</mo><mi>i</mi><mspace></mspace><mo>:</mo><mspace></mspace><mi>u</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>=</mo><mi>v</mi><mo>(</mo><mi>i</mi><mo>)</mo><mo>}</mo><mo>|</mo><mo>≥</mo><mi>t</mi></math></span> for all <span><math><mi>u</mi><mo>,</mo><mi>v</mi><mo>∈</mo><mi>A</mi></math></span>. In this paper, we consider the diversity and other intersecting theorems for weak compositions.</p></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"348 2\",\"pages\":\"Article 114250\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2024-09-11\",\"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/S0012365X24003819\",\"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/S0012365X24003819","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 N0 为非负整数集合,P(n,k) 表示 n 的所有 k 部分的弱合成集合,即 P(n,k)={(x1,x2,...,xk)∈N0k:x1+x2+⋯+xk=n}。对于任何元素 u=(u1,u2,...,uk)∈P(n,k),用 u(i) 表示其 ith 坐标,即 u(i)=ui 。对于所有 u,v∈A,如果|{i:u(i)=v(i)}|≥t,则称一个族 A⊆P(n,k)为 t 交族。在本文中,我们将考虑弱组合的多样性和其他相交定理。
Diversity and intersecting theorems for weak compositions
Let be the set of non-negative integers, and let denote the set of all weak compositions of n with k parts, i.e., . For any element , denote its ith-coordinate by , i.e., . A family is said to be t-intersecting if for all . In this paper, we consider the diversity and other intersecting theorems for weak compositions.
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.