{"title":"On the Colin de Verdière graph number and penny graphs","authors":"A.Y. Alfakih","doi":"10.1016/j.laa.2024.10.026","DOIUrl":null,"url":null,"abstract":"<div><div>The Colin de Verdière number of graph <em>G</em>, denoted by <span><math><mi>μ</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span>, is a spectral invariant of <em>G</em> that is related to some of its topological properties. For example, <span><math><mi>μ</mi><mo>(</mo><mi>G</mi><mo>)</mo><mo>≤</mo><mn>3</mn></math></span> iff <em>G</em> is planar. A <em>penny graph</em> is the contact graph of equal-radii disks with disjoint interiors in the plane. In this note, we prove lower bounds on <span><math><mi>μ</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> when the complement <span><math><mover><mrow><mi>G</mi></mrow><mo>‾</mo></mover></math></span> is a penny graph.</div></div>","PeriodicalId":18043,"journal":{"name":"Linear Algebra and its Applications","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Linear Algebra and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0024379524004117","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
The Colin de Verdière number of graph G, denoted by , is a spectral invariant of G that is related to some of its topological properties. For example, iff G is planar. A penny graph is the contact graph of equal-radii disks with disjoint interiors in the plane. In this note, we prove lower bounds on when the complement is a penny graph.
期刊介绍:
Linear Algebra and its Applications publishes articles that contribute new information or new insights to matrix theory and finite dimensional linear algebra in their algebraic, arithmetic, combinatorial, geometric, or numerical aspects. It also publishes articles that give significant applications of matrix theory or linear algebra to other branches of mathematics and to other sciences. Articles that provide new information or perspectives on the historical development of matrix theory and linear algebra are also welcome. Expository articles which can serve as an introduction to a subject for workers in related areas and which bring one to the frontiers of research are encouraged. Reviews of books are published occasionally as are conference reports that provide an historical record of major meetings on matrix theory and linear algebra.