报告题目：On the sum of the first two largest signless Laplacianeigenvalues of a graph

报告人:何常香 教授

报告时间:2025年10月30日(周四下午)16:00报告地点:腾讯会议(805-341-913)

报告摘要：For a graph$G$, let $S_2(G)$ be the sum of the first two largest signless Laplacian eigenvalues of $G$, and $f (G) = e(G)+3-S_2(G)$. 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 talk, we prove this conjecture, which also confirm a conjecture forthe upper bound of $S_2(G) $ proposed by Ashraf et al.

报告人简介:何常香，教授，博士生导师。主要从事图谱理论和图数据分析的研究，公开发表学术论文50余篇，主持多项国家自然科学基金。现任中国高等教育学会教育数学专业委员会理事、中国工业与应用数学学会图论组合及应用专业委员会委员。