On the sum of the first two largest signless Laplacian eigenvalues of a graph

被引:2
作者
Zhou, Zi-Ming [1 ]
He, Chang-Xiang [1 ]
Shan, Hai-Ying [2 ]
机构
[1] Univ Shanghai Sci & Technol, Coll Sci, Shanghai, Peoples R China
[2] Tongji Univ, Sch Math Sci, Shanghai, Peoples R China
基金
中国国家自然科学基金;
关键词
(Signless) Laplacian matrix; (Signless) Laplacian eigenvalues; Sum of (signless) Laplacian eigenvalues;
D O I
10.1016/j.disc.2024.114035
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
For a graph G, let S2(G) be the sum of the first two largest signless Laplacian eigenvalues of G, and f (G) = e(G) +3 -S2(G). Oliveira, Lima, Rama and Carvalho conjectured that K+1,n-1 (the star graph with an additional edge) is the unique graph with minimum value of f (G) on n vertices. In this paper, we prove this conjecture, which also confirm a conjecture for the upper bound of S2(G) proposed by Ashraf et al. (c) 2024 Elsevier B.V. All rights reserved.
引用
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页数:14
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