{"title":"特征值很少的数图","authors":"M. Cavers , B. Miraftab","doi":"10.1016/j.laa.2024.10.028","DOIUrl":null,"url":null,"abstract":"<div><div>This paper provides insight into the problem of characterizing digraphs (with loops permitted) that have few distinct adjacency eigenvalues, or equivalently, characterizing square <span><math><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></math></span>-matrices that have few distinct eigenvalues. A spectral characterization of strongly connected digraphs whose adjacency matrix has exactly two distinct eigenvalues is given and constructions of such digraphs are described. In addition, bipartite digraphs with exactly three distinct eigenvalues are discussed.</div></div>","PeriodicalId":18043,"journal":{"name":"Linear Algebra and its Applications","volume":"705 ","pages":"Pages 129-142"},"PeriodicalIF":1.0000,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Digraphs with few distinct eigenvalues\",\"authors\":\"M. Cavers , B. Miraftab\",\"doi\":\"10.1016/j.laa.2024.10.028\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>This paper provides insight into the problem of characterizing digraphs (with loops permitted) that have few distinct adjacency eigenvalues, or equivalently, characterizing square <span><math><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></math></span>-matrices that have few distinct eigenvalues. A spectral characterization of strongly connected digraphs whose adjacency matrix has exactly two distinct eigenvalues is given and constructions of such digraphs are described. In addition, bipartite digraphs with exactly three distinct eigenvalues are discussed.</div></div>\",\"PeriodicalId\":18043,\"journal\":{\"name\":\"Linear Algebra and its Applications\",\"volume\":\"705 \",\"pages\":\"Pages 129-142\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2024-11-06\",\"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/S0024379524004130\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Linear Algebra and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0024379524004130","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
This paper provides insight into the problem of characterizing digraphs (with loops permitted) that have few distinct adjacency eigenvalues, or equivalently, characterizing square -matrices that have few distinct eigenvalues. A spectral characterization of strongly connected digraphs whose adjacency matrix has exactly two distinct eigenvalues is given and constructions of such digraphs are described. In addition, bipartite digraphs with exactly three distinct eigenvalues are discussed.
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.