{"title":"最大 1 平面图中的大匹配","authors":"Therese Biedl , John Wittnebel","doi":"10.1016/j.disc.2024.114288","DOIUrl":null,"url":null,"abstract":"<div><div>It is well-known that every maximal planar graph has a matching of size at least <span><math><mfrac><mrow><mi>n</mi><mo>+</mo><mn>8</mn></mrow><mrow><mn>3</mn></mrow></mfrac></math></span> if <span><math><mi>n</mi><mo>≥</mo><mn>14</mn></math></span>. In this paper, we investigate similar matching-bounds for maximal <em>1-planar</em> graphs, i.e., graphs that can be drawn such that every edge has at most one crossing. In particular we show that every 3-connected simple-maximal 1-planar graph has a matching of size at least <span><math><mfrac><mrow><mn>2</mn><mi>n</mi><mo>+</mo><mn>6</mn></mrow><mrow><mn>5</mn></mrow></mfrac></math></span>; the bound decreases to <span><math><mfrac><mrow><mn>3</mn><mi>n</mi><mo>+</mo><mn>14</mn></mrow><mrow><mn>10</mn></mrow></mfrac></math></span> if the graph need not be 3-connected. We also give (weaker) bounds when the graph comes with a fixed 1-planar drawing or is not simple. All our bounds are tight in the sense that some graph that satisfies the restrictions has no bigger matching.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"348 2","pages":"Article 114288"},"PeriodicalIF":0.7000,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Large matchings in maximal 1-planar graphs\",\"authors\":\"Therese Biedl , John Wittnebel\",\"doi\":\"10.1016/j.disc.2024.114288\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>It is well-known that every maximal planar graph has a matching of size at least <span><math><mfrac><mrow><mi>n</mi><mo>+</mo><mn>8</mn></mrow><mrow><mn>3</mn></mrow></mfrac></math></span> if <span><math><mi>n</mi><mo>≥</mo><mn>14</mn></math></span>. In this paper, we investigate similar matching-bounds for maximal <em>1-planar</em> graphs, i.e., graphs that can be drawn such that every edge has at most one crossing. In particular we show that every 3-connected simple-maximal 1-planar graph has a matching of size at least <span><math><mfrac><mrow><mn>2</mn><mi>n</mi><mo>+</mo><mn>6</mn></mrow><mrow><mn>5</mn></mrow></mfrac></math></span>; the bound decreases to <span><math><mfrac><mrow><mn>3</mn><mi>n</mi><mo>+</mo><mn>14</mn></mrow><mrow><mn>10</mn></mrow></mfrac></math></span> if the graph need not be 3-connected. We also give (weaker) bounds when the graph comes with a fixed 1-planar drawing or is not simple. All our bounds are tight in the sense that some graph that satisfies the restrictions has no bigger matching.</div></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"348 2\",\"pages\":\"Article 114288\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2024-10-24\",\"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/S0012365X24004199\",\"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/S0012365X24004199","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
It is well-known that every maximal planar graph has a matching of size at least if . In this paper, we investigate similar matching-bounds for maximal 1-planar graphs, i.e., graphs that can be drawn such that every edge has at most one crossing. In particular we show that every 3-connected simple-maximal 1-planar graph has a matching of size at least ; the bound decreases to if the graph need not be 3-connected. We also give (weaker) bounds when the graph comes with a fixed 1-planar drawing or is not simple. All our bounds are tight in the sense that some graph that satisfies the restrictions has no bigger matching.
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.