European Journal of Combinatorics最新文献_第2页

Product representation of perfect cubes 完全立方的积表示

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-01-23 DOI: 10.1016/j.ejc.2026.104342

Zsigmond György Fleiner , Márk Hunor Juhász , Blanka Kövér , Péter Pál Pach , Csaba Sándor

引用次数: 0

The partial derivative of ratios of Schur polynomials and applications to symplectic quotients 舒尔多项式比值的偏导数及其在辛商中的应用

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-02-07 DOI: 10.1016/j.ejc.2026.104351

Hans-Christian Herbig , Daniel Herden , Harper Kolehmainen , Christopher Seaton

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引用次数: 0

A note on the maximum diversity of intersecting families in the symmetric group 对称群中相交族的最大多样性的注记

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2025-12-31 DOI: 10.1016/j.ejc.2025.104331

Jian Wang , Jimeng Xiao

{"title":"A note on the maximum diversity of intersecting families in the symmetric group","authors":"Jian Wang , Jimeng Xiao","doi":"10.1016/j.ejc.2025.104331","DOIUrl":"10.1016/j.ejc.2025.104331","url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> be the symmetric group on the set <span><math><mrow><mrow><mo>[</mo><mi>n</mi><mo>]</mo></mrow><mo>≔</mo><mrow><mo>{</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>n</mi><mo>}</mo></mrow></mrow></math></span>. A family <span><math><mrow><mi>F</mi><mo>⊂</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></mrow></math></span> is called intersecting if for every <span><math><mrow><mi>σ</mi><mo>,</mo><mi>π</mi><mo>∈</mo><mi>F</mi></mrow></math></span> there exists some <span><math><mrow><mi>i</mi><mo>∈</mo><mrow><mo>[</mo><mi>n</mi><mo>]</mo></mrow></mrow></math></span> such that <span><math><mrow><mi>σ</mi><mrow><mo>(</mo><mi>i</mi><mo>)</mo></mrow><mo>=</mo><mi>π</mi><mrow><mo>(</mo><mi>i</mi><mo>)</mo></mrow></mrow></math></span>. Deza and Frankl proved that the largest intersecting family of permutations is the full star, that is, the collection of all permutations with a fixed position. The diversity of an intersecting family <span><math><mi>F</mi></math></span> is defined as the minimum number of permutations in <span><math><mi>F</mi></math></span>, whose deletion results in a star. In the present paper, by applying the spread approximation method developed recently by Kupavskii and Zakharov, we prove that for <span><math><mrow><mi>n</mi><mo>≥</mo><mn>500</mn></mrow></math></span> the diversity of an intersecting subfamily of <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span> is at most <span><math><mrow><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mn>3</mn><mo>)</mo></mrow><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mn>3</mn><mo>)</mo></mrow><mo>!</mo></mrow></math></span>, which is best possible.</div></div>","PeriodicalId":50490,"journal":{"name":"European Journal of Combinatorics","volume":"134 ","pages":"Article 104331"},"PeriodicalIF":0.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145872451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Strong modeling limits of graphs with bounded tree-width 有界树宽图的强建模限制

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-01-19 DOI: 10.1016/j.ejc.2025.104330

Andrzej Grzesik , Daniel Král , Samuel Mohr

引用次数: 0

Polynomials counting group colorings in graphs 图中多项式计数群着色

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-02-04 DOI: 10.1016/j.ejc.2026.104348

Houshan Fu

引用次数: 0

Path decompositions of oriented graphs 有向图的路径分解

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-02-03 DOI: 10.1016/j.ejc.2026.104346

Viresh Patel , Mehmet Akif Yıldız

{"title":"Path decompositions of oriented graphs","authors":"Viresh Patel , Mehmet Akif Yıldız","doi":"10.1016/j.ejc.2026.104346","DOIUrl":"10.1016/j.ejc.2026.104346","url":null,"abstract":"<div><div>We consider the problem of decomposing the edges of a digraph into as few paths as possible. A natural lower bound for the number of paths in any path decomposition of a digraph <span><math><mi>D</mi></math></span> is <span><math><mrow><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><msub><mrow><mo>∑</mo></mrow><mrow><mi>v</mi><mo>∈</mo><mi>V</mi><mrow><mo>(</mo><mi>D</mi><mo>)</mo></mrow></mrow></msub><mrow><mo>|</mo><msup><mrow><mi>d</mi></mrow><mrow><mo>+</mo></mrow></msup><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow><mo>−</mo><msup><mrow><mi>d</mi></mrow><mrow><mo>−</mo></mrow></msup><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow><mo>|</mo></mrow></mrow></math></span>; any digraph that achieves this bound is called consistent. Alspach et al. 1976 conjectured in 1976 that every tournament of even order is consistent and this was recently verified for large tournaments by Girão et al. 2023. A more general conjecture of Pullman (Reid and Wayland, 1987) states that for odd <span><math><mi>d</mi></math></span>, every orientation of a <span><math><mi>d</mi></math></span>-regular graph is consistent. We prove that the conjecture holds for random <span><math><mi>d</mi></math></span>-regular graphs with high probability i.e. for fixed odd <span><math><mi>d</mi></math></span> and as <span><math><mrow><mi>n</mi><mo>→</mo><mi>∞</mi></mrow></math></span> the conjecture holds for almost all <span><math><mi>d</mi></math></span>-regular graphs. Along the way, we verify Pullman’s conjecture for graphs whose girth is sufficiently large (as a function of the degree).</div></div>","PeriodicalId":50490,"journal":{"name":"European Journal of Combinatorics","volume":"134 ","pages":"Article 104346"},"PeriodicalIF":0.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Unions of intervals in codes based on powers of sets 基于集合幂的码中区间的并集

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-04-01 Epub Date: 2026-02-10 DOI: 10.1016/j.ejc.2026.104350

Thomas Karam

引用次数: 0

A self-conjugate partition analog of (t,t+1)-core partitions with distinct parts 具有不同部分的（t,t+1）核划分的自共轭划分模拟

IF 0.9 3区数学

European Journal of Combinatorics Pub Date : 2026-03-01 Epub Date: 2025-12-22 DOI: 10.1016/j.ejc.2025.104322

Huan Xiong, Lihong Yang

引用次数: 0

Order polytopes of crown posets 冠位集的序多面体