{"title":"On platypus graphs and the Steiner–Deogun property","authors":"Carol T. Zamfirescu","doi":"10.1016/j.dam.2025.06.048","DOIUrl":null,"url":null,"abstract":"<div><div>A <em>platypus</em> is a non-hamiltonian graph in which every vertex-deleted subgraph is traceable. We prove a series of results on platypus graphs. For instance, although there are planar platypuses and bipartite platypuses, it is not known whether there is a planar bipartite platypus. Motivated by this question, we show that every tree is an induced subgraph of some planar platypus. On the other hand, there exists an infinite family of planar graphs each member of which is not an induced subgraph of any planar platypus. Throughout the article we point out connections between platypus graphs and graphs having the Steiner–Deogun property, as defined by Kratsch, Lehel, and Müller.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"377 ","pages":"Pages 87-94"},"PeriodicalIF":1.0000,"publicationDate":"2025-07-04","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/S0166218X25003658","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
A platypus is a non-hamiltonian graph in which every vertex-deleted subgraph is traceable. We prove a series of results on platypus graphs. For instance, although there are planar platypuses and bipartite platypuses, it is not known whether there is a planar bipartite platypus. Motivated by this question, we show that every tree is an induced subgraph of some planar platypus. On the other hand, there exists an infinite family of planar graphs each member of which is not an induced subgraph of any planar platypus. Throughout the article we point out connections between platypus graphs and graphs having the Steiner–Deogun property, as defined by Kratsch, Lehel, and Müller.
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.
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