Shanshan Zhang , Xiumei Wang , Jinjiang Yuan , C.T. Ng , T.C.E. Cheng
{"title":"平面图中的偶环与完美匹配","authors":"Shanshan Zhang , Xiumei Wang , Jinjiang Yuan , C.T. Ng , T.C.E. Cheng","doi":"10.1016/j.dam.2025.08.013","DOIUrl":null,"url":null,"abstract":"<div><div>Ear decomposition is a powerful tool for the study of the structure of matchings and enumeration of matchings. Lovász showed that a matching covered graph <span><math><mi>G</mi></math></span> has an ear decomposition starting with an arbitrary edge of <span><math><mi>G</mi></math></span>. A graph <span><math><mi>G</mi></math></span> is cycle-nice if, for each even cycle <span><math><mi>C</mi></math></span> in <span><math><mi>G</mi></math></span>, <span><math><mrow><mi>G</mi><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>C</mi><mo>)</mo></mrow></mrow></math></span> has a perfect matching. A matching covered graph <span><math><mi>G</mi></math></span> has ear decompositions starting with an arbitrary even cycle in <span><math><mi>G</mi></math></span> if and only if <span><math><mi>G</mi></math></span> is a cycle-nice graph. In this paper we show that the only simple cycle-nice 3-connected planar graphs are the odd wheels and the odd prisms. Using this characterization, we show that every cycle-nice matching covered planar graph is an even cycle with multiple edges, or can be obtained from an odd wheel or an odd prism by a sequence of three types of operations.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"378 ","pages":"Pages 468-479"},"PeriodicalIF":1.0000,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Even cycles and perfect matchings in planar graphs\",\"authors\":\"Shanshan Zhang , Xiumei Wang , Jinjiang Yuan , C.T. Ng , T.C.E. Cheng\",\"doi\":\"10.1016/j.dam.2025.08.013\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Ear decomposition is a powerful tool for the study of the structure of matchings and enumeration of matchings. Lovász showed that a matching covered graph <span><math><mi>G</mi></math></span> has an ear decomposition starting with an arbitrary edge of <span><math><mi>G</mi></math></span>. A graph <span><math><mi>G</mi></math></span> is cycle-nice if, for each even cycle <span><math><mi>C</mi></math></span> in <span><math><mi>G</mi></math></span>, <span><math><mrow><mi>G</mi><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>C</mi><mo>)</mo></mrow></mrow></math></span> has a perfect matching. A matching covered graph <span><math><mi>G</mi></math></span> has ear decompositions starting with an arbitrary even cycle in <span><math><mi>G</mi></math></span> if and only if <span><math><mi>G</mi></math></span> is a cycle-nice graph. In this paper we show that the only simple cycle-nice 3-connected planar graphs are the odd wheels and the odd prisms. Using this characterization, we show that every cycle-nice matching covered planar graph is an even cycle with multiple edges, or can be obtained from an odd wheel or an odd prism by a sequence of three types of operations.</div></div>\",\"PeriodicalId\":50573,\"journal\":{\"name\":\"Discrete Applied Mathematics\",\"volume\":\"378 \",\"pages\":\"Pages 468-479\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2025-08-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Applied Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166218X25004494\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS, APPLIED\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Applied Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166218X25004494","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
Even cycles and perfect matchings in planar graphs
Ear decomposition is a powerful tool for the study of the structure of matchings and enumeration of matchings. Lovász showed that a matching covered graph has an ear decomposition starting with an arbitrary edge of . A graph is cycle-nice if, for each even cycle in , has a perfect matching. A matching covered graph has ear decompositions starting with an arbitrary even cycle in if and only if is a cycle-nice graph. In this paper we show that the only simple cycle-nice 3-connected planar graphs are the odd wheels and the odd prisms. Using this characterization, we show that every cycle-nice matching covered planar graph is an even cycle with multiple edges, or can be obtained from an odd wheel or an odd prism by a sequence of three types of operations.
期刊介绍:
The aim of Discrete Applied Mathematics is to bring together research papers in different areas of algorithmic and applicable discrete mathematics as well as applications of combinatorial mathematics to informatics and various areas of science and technology. Contributions presented to the journal can be research papers, short notes, surveys, and possibly research problems. The "Communications" section will be devoted to the fastest possible publication of recent research results that are checked and recommended for publication by a member of the Editorial Board. The journal will also publish a limited number of book announcements as well as proceedings of conferences. These proceedings will be fully refereed and adhere to the normal standards of the journal.
Potential authors are advised to view the journal and the open calls-for-papers of special issues before submitting their manuscripts. Only high-quality, original work that is within the scope of the journal or the targeted special issue will be considered.