On Graphs with Three or Four Distinct Normalized Laplacian Eigenvalues  

作　　者：Xueyi Huang Qiongxiang Huang 

机构地区：[1]School of Mathematics and Statistics, Zhengzhou University Zhengzhou 450001, China [2]College of Mathematics and Systems Science, Xinjiang University Urumqi 830046, China

出　　处：《Algebra Colloquium》2019年第1期65-82,共18页代数集刊（英文版）

基　　金：This work is supported by the National Natural Science Foundation of China (grants No. 11671344, 11531011 and 11701492).

摘　　要：We characterize all connected graphs with exactly three distinct normalized Laplacian eigenvalues among which one is equal to 1, and determine all connected bipartite graphs with at least one vertex of degree 1 having exactly four distinct normalized Laplacian eigenvalues. In addition, we find all unicyclic graphs with three or four distinct normalized Laplacian eigenvalues.

关 键 词：normalized LAPLACIAN eigenvalue BIPARTITE GRAPH symmetrie BIBD unicyclic GRAPH HADAMARD matrix 

分 类 号：O1[理学—数学]