{"title":"Zpk 中权重为零的有向循环","authors":"Shoham Letzter , Natasha Morrison","doi":"10.1016/j.jctb.2024.05.002","DOIUrl":null,"url":null,"abstract":"<div><p>For a finite abelian group <em>A</em>, define <span><math><mi>f</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> to be the minimum integer such that for every complete digraph Γ on <em>f</em> vertices and every map <span><math><mi>w</mi><mo>:</mo><mi>E</mi><mo>(</mo><mi>Γ</mi><mo>)</mo><mo>→</mo><mi>A</mi></math></span>, there exists a directed cycle <em>C</em> in Γ such that <span><math><msub><mrow><mo>∑</mo></mrow><mrow><mi>e</mi><mo>∈</mo><mi>E</mi><mo>(</mo><mi>C</mi><mo>)</mo></mrow></msub><mi>w</mi><mo>(</mo><mi>e</mi><mo>)</mo><mo>=</mo><mn>0</mn></math></span>. The study of <span><math><mi>f</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> was initiated by Alon and Krivelevich (2021). In this article, we prove that <span><math><mi>f</mi><mo>(</mo><msubsup><mrow><mi>Z</mi></mrow><mrow><mi>p</mi></mrow><mrow><mi>k</mi></mrow></msubsup><mo>)</mo><mo>=</mo><mi>O</mi><mo>(</mo><mi>p</mi><mi>k</mi><msup><mrow><mo>(</mo><mi>log</mi><mo></mo><mi>k</mi><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>, where <em>p</em> is prime, with an improved bound of <span><math><mi>O</mi><mo>(</mo><mi>k</mi><mi>log</mi><mo></mo><mi>k</mi><mo>)</mo></math></span> when <span><math><mi>p</mi><mo>=</mo><mn>2</mn></math></span>. These bounds are tight up to a factor which is polylogarithmic in <em>k</em>.</p></div>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0095895624000418/pdfft?md5=5e9d14a46eed8e2ee2946b39a3ab2037&pid=1-s2.0-S0095895624000418-main.pdf","citationCount":"0","resultStr":"{\"title\":\"Directed cycles with zero weight in Zpk\",\"authors\":\"Shoham Letzter , Natasha Morrison\",\"doi\":\"10.1016/j.jctb.2024.05.002\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>For a finite abelian group <em>A</em>, define <span><math><mi>f</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> to be the minimum integer such that for every complete digraph Γ on <em>f</em> vertices and every map <span><math><mi>w</mi><mo>:</mo><mi>E</mi><mo>(</mo><mi>Γ</mi><mo>)</mo><mo>→</mo><mi>A</mi></math></span>, there exists a directed cycle <em>C</em> in Γ such that <span><math><msub><mrow><mo>∑</mo></mrow><mrow><mi>e</mi><mo>∈</mo><mi>E</mi><mo>(</mo><mi>C</mi><mo>)</mo></mrow></msub><mi>w</mi><mo>(</mo><mi>e</mi><mo>)</mo><mo>=</mo><mn>0</mn></math></span>. The study of <span><math><mi>f</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> was initiated by Alon and Krivelevich (2021). In this article, we prove that <span><math><mi>f</mi><mo>(</mo><msubsup><mrow><mi>Z</mi></mrow><mrow><mi>p</mi></mrow><mrow><mi>k</mi></mrow></msubsup><mo>)</mo><mo>=</mo><mi>O</mi><mo>(</mo><mi>p</mi><mi>k</mi><msup><mrow><mo>(</mo><mi>log</mi><mo></mo><mi>k</mi><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>, where <em>p</em> is prime, with an improved bound of <span><math><mi>O</mi><mo>(</mo><mi>k</mi><mi>log</mi><mo></mo><mi>k</mi><mo>)</mo></math></span> when <span><math><mi>p</mi><mo>=</mo><mn>2</mn></math></span>. These bounds are tight up to a factor which is polylogarithmic in <em>k</em>.</p></div>\",\"PeriodicalId\":1,\"journal\":{\"name\":\"Accounts of Chemical Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":16.4000,\"publicationDate\":\"2024-05-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S0095895624000418/pdfft?md5=5e9d14a46eed8e2ee2946b39a3ab2037&pid=1-s2.0-S0095895624000418-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Accounts of Chemical Research\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0095895624000418\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0095895624000418","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
对于有限无边群 A,定义 f(A) 为最小整数,即对于 f 个顶点上的每个完整图 Γ 和每个映射 w:E(Γ)→A, Γ 中存在一个有向循环 C,使得∑e∈E(C)w(e)=0。 f(A) 的研究由 Alon 和 Krivelevich (2021) 发起。在这篇文章中,我们证明了 f(Zpk)=O(pk(logk)2),其中 p 是素数,当 p=2 时的改进边界为 O(klogk)。这些界值在 k 的多对数因子以内都很紧。
For a finite abelian group A, define to be the minimum integer such that for every complete digraph Γ on f vertices and every map , there exists a directed cycle C in Γ such that . The study of was initiated by Alon and Krivelevich (2021). In this article, we prove that , where p is prime, with an improved bound of when . These bounds are tight up to a factor which is polylogarithmic in k.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
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