On the sum of Laplacian eigenvalues of graphs

被引:45
作者
Haemers, W. H. [1 ]
Mohammadian, A. [2 ,3 ]
Tayfeh-Rezaie, B. [3 ]
机构
[1] Tilburg Univ, Dept Econometr & Operat Res, NL-5000 LE Tilburg, Netherlands
[2] Amirkabir Univ Technol, Fac Math & Comp Sci, Tehran, Iran
[3] IPM, Sch Math, Inst Res Fundamental Sci, Tehran, Iran
关键词
Laplacian eigenvalues of a graph; Sum of eigenvalues; Largest eigenvalue;
D O I
10.1016/j.laa.2009.03.038
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Let k be a natural number and let G be a graph with at least k vertices. Brouwer conjectured that the sum of the k largest Laplacian eigen-values of G is at most e(G) + ((2) (k + 1)), where e(G) is the number of edges of G. We prove this conjecture for k = 2. We also show that if G is a tree, then the sum of the k largest Laplacian eigenvalues of G is at most e(G) + 2k - 1. (C) 2009 Elsevier Inc. All rights reserved.
引用
收藏
页码:2214 / 2221
页数:8
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