Journal of Graph Theory最新文献_第4页

On a conjecture that strengthens Kundu's k

k

-factor theorem

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-10-06 DOI: 10.1002/jgt.23177

James M. Shook

{"title":"On a conjecture that strengthens Kundu's \u0000 \u0000 \u0000 \u0000 k\u0000 \u0000 \u0000 <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23177:jgt23177-math-0001\" wiley:location=\"equation/jgt23177-math-0001.png\"><mrow><mrow><mi>k</mi></mrow></mrow></math>\u0000 -factor theorem","authors":"James M. Shook","doi":"10.1002/jgt.23177","DOIUrl":"https://doi.org/10.1002/jgt.23177","url":null,"abstract":"Let <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>π</mi>\u0000 \u0000 <mo>=</mo>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>d</mi>\u0000 \u0000 <mn>1</mn>\u0000 </msub>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mi>…</mi>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <msub>\u0000 <mi>d</mi>\u0000 \u0000 <mi>n</mi>\u0000 </msub>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23177:jgt23177-math-0002\" wiley:location=\"equation/jgt23177-math-0002.png\"><mrow><mrow><mi>unicode{x003C0}</mi><mo>=</mo><mrow><mo>(</mo><mrow><msub><mi>d</mi><mn>1</mn></msub><mo>,</mo><mo>unicode{x02026}</mo><mo>,</mo><msub><mi>d</mi><mi>n</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow></math></annotation>\u0000 </semantics></math> be a nonincreasing degree sequence with even <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>n</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23177:jgt23177-math-0003\" wiley:location=\"equation/jgt23177-math-0003.png\"><mrow><mrow><mi>n</mi></mrow></mrow></math></annotation>\u0000 </semantics></math>. In 1974, Kundu showed that if <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>D</mi>\u0000 \u0000 <mi>k</mi>\u0000 </msub>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mi>π</mi>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mo>=</mo>\u0000 \u0000 <mrow>\u0000 <mo","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 3","pages":"463-491"},"PeriodicalIF":0.9,"publicationDate":"2024-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112839","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

On the Constructor–Blocker game

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-10-06 DOI: 10.1002/jgt.23186

József Balogh, Ce Chen, Sean English

{"title":"On the Constructor–Blocker game","authors":"József Balogh, Ce Chen, Sean English","doi":"10.1002/jgt.23186","DOIUrl":"https://doi.org/10.1002/jgt.23186","url":null,"abstract":"In the Constructor–Blocker game, two players, Constructor and Blocker, alternately claim unclaimed edges of the complete graph <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>K</mi>\u0000 \u0000 <mi>n</mi>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23186:jgt23186-math-0001\" wiley:location=\"equation/jgt23186-math-0001.png\"><mrow><mrow><msub><mi>K</mi><mi>n</mi></msub></mrow></mrow></math></annotation>\u0000 </semantics></math>. For given graphs <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23186:jgt23186-math-0002\" wiley:location=\"equation/jgt23186-math-0002.png\"><mrow><mrow><mi>F</mi></mrow></mrow></math></annotation>\u0000 </semantics></math> and <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>H</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23186:jgt23186-math-0003\" wiley:location=\"equation/jgt23186-math-0003.png\"><mrow><mrow><mi>H</mi></mrow></mrow></math></annotation>\u0000 </semantics></math>, Constructor can only claim edges that leave her graph <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23186:jgt23186-math-0004\" wiley:location=\"equation/jgt23186-math-0004.png\"><mrow><mrow><mi>F</mi></mrow></mrow></math></annotation>\u0000 </semantics></math>-free, while Blocker has no restrictions. Constructor's goal is to build as many copies of <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>H</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23186:jgt23186-math-0005\" wiley:location=\"equation/jgt23186-math-0005.png\"><mrow><mrow><mi>H</mi></mrow></mrow></","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 3","pages":"492-507"},"PeriodicalIF":0.9,"publicationDate":"2024-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112840","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

Super stable tensegrities and the Colin de Verdière number ν

unicode{x003BD}

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-10-02 DOI: 10.1002/jgt.23188

Ryoshun Oba, Shin-ichi Tanigawa

{"title":"Super stable tensegrities and the Colin de Verdière number \u0000 \u0000 \u0000 \u0000 ν\u0000 \u0000 \u0000 <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23188:jgt23188-math-0001\" wiley:location=\"equation/jgt23188-math-0001.png\"><mrow><mrow><mi>unicode{x003BD}</mi></mrow></mrow></math>","authors":"Ryoshun Oba, Shin-ichi Tanigawa","doi":"10.1002/jgt.23188","DOIUrl":"https://doi.org/10.1002/jgt.23188","url":null,"abstract":"A super stable tensegrity introduced by Connelly in 1982 is a globally rigid discrete structure made from stiff bars and struts connected by cables with tension. We introduce the super stability number of a multigraph as the maximum dimension that a multigraph can be realized as a super stable tensegrity, and show that it equals the Colin de Verdière number <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>ν</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23188:jgt23188-math-0002\" wiley:location=\"equation/jgt23188-math-0002.png\"><mrow><mrow><mi>unicode{x003BD}</mi></mrow></mrow></math></annotation>\u0000 </semantics></math> minus one. As a corollary we obtain a combinatorial characterization of multigraphs that can be realized as three-dimensional super stable tensegrities. We also show that, for any fixed <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>d</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23188:jgt23188-math-0003\" wiley:location=\"equation/jgt23188-math-0003.png\"><mrow><mrow><mi>d</mi></mrow></mrow></math></annotation>\u0000 </semantics></math>, there is an infinite family of 3-regular graphs that can be realized as <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>d</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> <math xmlns=\"http://www.w3.org/1998/Math/MathML\" altimg=\"urn:x-wiley:03649024:media:jgt23188:jgt23188-math-0004\" wiley:location=\"equation/jgt23188-math-0004.png\"><mrow><mrow><mi>d</mi></mrow></mrow></math></annotation>\u0000 </semantics></math>-dimensional injective super stable tensegrities.","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 3","pages":"401-431"},"PeriodicalIF":0.9,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jgt.23188","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Counting circuit double covers 计数电路双盖

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-10-02 DOI: 10.1002/jgt.23187

Radek Hušek, Robert Šámal

{"title":"Counting circuit double covers","authors":"Radek Hušek, Robert Šámal","doi":"10.1002/jgt.23187","DOIUrl":"https://doi.org/10.1002/jgt.23187","url":null,"abstract":"We study a counting version of Cycle Double Cover Conjecture. We discuss why it is more interesting to count circuits (i.e., graphs isomorphic to <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>C</mi>\u0000 \u0000 <mi>k</mi>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${C}_{k}$</annotation>\u0000 </semantics></math> for some <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math>) instead of cycles (graphs with all degrees even). We give an almost-exponential lower bound for graphs with a surface embedding of representativity at least 4. We also prove an exponential lower bound for planar graphs. We conjecture that any bridgeless cubic graph has at least <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msup>\u0000 <mn>2</mn>\u0000 \u0000 <mrow>\u0000 <mi>n</mi>\u0000 \u0000 <mo>/</mo>\u0000 \u0000 <mn>2</mn>\u0000 \u0000 <mo>−</mo>\u0000 \u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${2}^{n/2-1}$</annotation>\u0000 </semantics></math> circuit double covers and we show an infinite class of graphs for which this bound is tight.","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"374-395"},"PeriodicalIF":0.9,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jgt.23187","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142868031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Non-Hamiltonian Cartesian products of two even dicycles 两个偶双环的非哈密顿笛卡尔积

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-30 DOI: 10.1002/jgt.23185

Kenta Noguchi, Carol T. Zamfirescu

{"title":"Non-Hamiltonian Cartesian products of two even dicycles","authors":"Kenta Noguchi, Carol T. Zamfirescu","doi":"10.1002/jgt.23185","DOIUrl":"https://doi.org/10.1002/jgt.23185","url":null,"abstract":"In this note it is proven that there exist infinitely many positive integers <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>a</mi>\u0000 </mrow>\u0000 <annotation> $a$</annotation>\u0000 </semantics></math> and <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>b</mi>\u0000 </mrow>\u0000 <annotation> $b$</annotation>\u0000 </semantics></math> such that the Cartesian product of a directed cycle of length <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 \u0000 <mi>a</mi>\u0000 </mrow>\u0000 <annotation> $2a$</annotation>\u0000 </semantics></math> and a directed cycle of length <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 \u0000 <mi>b</mi>\u0000 </mrow>\u0000 <annotation> $2b$</annotation>\u0000 </semantics></math> is non-Hamiltonian. In particular, the Cartesian product of an 880-dicycle and a 4368-dicycle is non-Hamiltonian. We also prove that there is no such graph on fewer than <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>880</mn>\u0000 \u0000 <mo>⋅</mo>\u0000 \u0000 <mn>4368</mn>\u0000 \u0000 <mo>=</mo>\u0000 \u0000 <mn>3</mn>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mn>843</mn>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mn>840</mn>\u0000 </mrow>\u0000 <annotation> $880cdot 4368=3,843,840$</annotation>\u0000 </semantics></math> vertices, which is rather astonishing.","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"368-373"},"PeriodicalIF":0.9,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869244","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

An extension of Nash-Williams and Tutte's Theorem 纳什-威廉姆斯和图特定理的推广

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-26 DOI: 10.1002/jgt.23189

Xuqian Fang, Daqing Yang

{"title":"An extension of Nash-Williams and Tutte's Theorem","authors":"Xuqian Fang, Daqing Yang","doi":"10.1002/jgt.23189","DOIUrl":"https://doi.org/10.1002/jgt.23189","url":null,"abstract":"The celebrated Nash-Williams and Tutte's Theorem states that a graph <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $G$</annotation>\u0000 </semantics></math> contains <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math> edge-disjoint spanning trees if and only if <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>ν</mi>\u0000 \u0000 <mi>f</mi>\u0000 </msub>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mi>G</mi>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mo>≥</mo>\u0000 \u0000 <mi>k</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${nu }_{f}(G)ge k$</annotation>\u0000 </semantics></math>, where\u0000\u0000 In this paper, we prove that, for integers <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>k</mi>\u0000 \u0000 <mo>≥</mo>\u0000 \u0000 <mn>0</mn>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $kge 0$</annotation>\u0000 </semantics></math>, <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>d</mi>\u0000 \u0000 <mo>≥</mo>\u0000 \u0000 <mn>1</mn>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $dge 1$</annotation>\u0000 </semantics></math>, if <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>ν</mi>\u0000 \u0000 <mi>f</mi>\u0000 </msub>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mi>G</mi>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mo>></mo>\u0000 \u0000 <mi>k</mi>\u0000 \u0000 <mo>+</mo>\u0000 \u0000 <mfrac>\u0000 <mrow>\u0000 ","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"361-367"},"PeriodicalIF":0.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869216","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

Graph curvature and local discrepancy 图曲率和局部差异

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-24 DOI: 10.1002/jgt.23176

Paul Horn, Adam Purcilly, Alex Stevens

{"title":"Graph curvature and local discrepancy","authors":"Paul Horn, Adam Purcilly, Alex Stevens","doi":"10.1002/jgt.23176","DOIUrl":"https://doi.org/10.1002/jgt.23176","url":null,"abstract":"In recent years, discrete notions of curvature have been defined and exploited to understand various geometric properties of graphs; especially regarding heat flow, and spectral properties. In this paper, we study various combinatorial properties implied by satisfying the Bakry–Émery curvature dimension inequality <math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>C</mi>\u0000 \u0000 <mi>D</mi>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mrow>\u0000 <mi>∞</mi>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mi>K</mi>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $CD(infty ,K)$</annotation>\u0000 </semantics></math>. In particular we derive a local discrepancy inequality, similar in spirit to the expander mixing lemma from spectral graph theory, which certifies a type of “local pseudo-randomness” of the edge set of the graph, for graphs satisfying a curvature lower bound. In addition, several other consequences are derived regarding graph connectivity and cycle statistics of the graph.","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"337-360"},"PeriodicalIF":0.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869195","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

Short rainbow cycles for families of matchings and triangles 短彩虹周期的家庭匹配和三角形

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-23 DOI: 10.1002/jgt.23183

He Guo

{"title":"Short rainbow cycles for families of matchings and triangles","authors":"He Guo","doi":"10.1002/jgt.23183","DOIUrl":"https://doi.org/10.1002/jgt.23183","url":null,"abstract":"A generalization of the famous Caccetta–Häggkvist conjecture, suggested by Aharoni, is that any family <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>F</mi>\u0000 \u0000 <mo>=</mo>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <msub>\u0000 <mi>F</mi>\u0000 \u0000 <mn>1</mn>\u0000 </msub>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mi>…</mi>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <msub>\u0000 <mi>F</mi>\u0000 \u0000 <mi>n</mi>\u0000 </msub>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${rm{ {mathcal F} }}=({F}_{1},ldots ,{F}_{n})$</annotation>\u0000 </semantics></math> of sets of edges in <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>K</mi>\u0000 \u0000 <mi>n</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${K}_{n}$</annotation>\u0000 </semantics></math>, each of size <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math>, has a rainbow cycle of length at most <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>⌈</mo>\u0000 \u0000 <mfrac>\u0000 <mi>n</mi>\u0000 \u0000 <mi>k</mi>\u0000 </mfrac>\u0000 \u0000 <mo>⌉</mo>\u0000 </mrow>\u0000 <annotation> $lceil frac{n}{k}rceil $</annotation>\u0000 </semantics></math>. In works by the author with Aharoni and by the author with Aharoni, Berger, Chudnovsky, and Zerbib, it was shown that asymptotically this can be improved to <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>log</mi>\u0000 \u0000 <mi>n</mi>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $O(mathrm{log}n)$</annotation>\u0000 </se","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"325-336"},"PeriodicalIF":0.9,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jgt.23183","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142868944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On two problems of defective choosability of graphs 论图的缺陷选择性的两个问题

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-23 DOI: 10.1002/jgt.23182

Jie Ma, Rongxing Xu, Xuding Zhu

{"title":"On two problems of defective choosability of graphs","authors":"Jie Ma, Rongxing Xu, Xuding Zhu","doi":"10.1002/jgt.23182","DOIUrl":"https://doi.org/10.1002/jgt.23182","url":null,"abstract":"Given positive integers <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>p</mi>\u0000 <mo>≥</mo>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $pge k$</annotation>\u0000 </semantics></math>, and a nonnegative integer <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>d</mi>\u0000 </mrow>\u0000 <annotation> $d$</annotation>\u0000 </semantics></math>, we say a graph <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>G</mi>\u0000 </mrow>\u0000 <annotation> $G$</annotation>\u0000 </semantics></math> is <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 <mo>,</mo>\u0000 <mi>d</mi>\u0000 <mo>,</mo>\u0000 <mi>p</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(k,d,p)$</annotation>\u0000 </semantics></math>-choosable if for every list assignment <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 </mrow>\u0000 <annotation> $L$</annotation>\u0000 </semantics></math> with <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∣</mo>\u0000 <mi>L</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>v</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <mo>∣</mo>\u0000 <mo>≥</mo>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $| L(v)| ge k$</annotation>\u0000 </semantics></math> for each <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>v</mi>\u0000 <mo>∈</mo>\u0000 <mi>V</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>G</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $vin V(G)$</annotation>\u0000 </semantics></math> and <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∣</mo>\u0000 <msub>\u0000 <mo>⋃</mo>\u0000 <mrow>\u0000 <mi>v</mi>\u0000 <mo>∈</mo>\u0000 <mi>V</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>G</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 </msub>\u0000 <mi>L</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>v</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 ","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"313-324"},"PeriodicalIF":0.9,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142868925","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

d $d$ -connectivity of the random graph with restricted budget D $ D $ -有限预算随机图的连通性

IF 0.9 3区数学

Journal of Graph Theory Pub Date : 2024-09-18 DOI: 10.1002/jgt.23180

Lyuben Lichev

{"title":"d\u0000 \u0000 $d$\u0000 -connectivity of the random graph with restricted budget","authors":"Lyuben Lichev","doi":"10.1002/jgt.23180","DOIUrl":"https://doi.org/10.1002/jgt.23180","url":null,"abstract":"In this short note, we consider a graph process recently introduced by Frieze, Krivelevich and Michaeli. In their model, the edges of the complete graph <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>K</mi>\u0000 \u0000 <mi>n</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${K}_{n}$</annotation>\u0000 </semantics></math> are ordered uniformly at random and are then revealed consecutively to a player called Builder. At every round, Builder must decide if they accept the edge proposed at this round or not. We prove that, for every <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>d</mi>\u0000 \u0000 <mo>≥</mo>\u0000 \u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $dge 2$</annotation>\u0000 </semantics></math>, Builder can construct a spanning <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>d</mi>\u0000 </mrow>\u0000 <annotation> $d$</annotation>\u0000 </semantics></math>-connected graph after <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mn>1</mn>\u0000 \u0000 <mo>+</mo>\u0000 \u0000 <mi>o</mi>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mn>1</mn>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mi>n</mi>\u0000 \u0000 <mi>log</mi>\u0000 \u0000 <mo> </mo>\u0000 \u0000 <mi>n</mi>\u0000 \u0000 <mo>/</mo>\u0000 \u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $(1+o(1))nmathrm{log}unicode{x0200A}n/2$</annotation>\u0000 </semantics></math> rounds by accepting <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mn>1</mn>\u0000 \u0000 <mo>+</mo>\u0000 \u0000 <mi>o</mi>\u0000 \u0000 <mrow>\u0000 <mo>(</mo>\u0000 \u0000 <mn>1</mn>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mo>)</mo>\u0000 </mrow>\u0000 \u0000 <mi>d</mi>\u0000 \u0000 <mi>n</mi>\u0000 \u0000 ","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"108 2","pages":"293-312"},"PeriodicalIF":0.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142868961","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