报告人：王力工教授

报告时间：2025/11/18 10:00  

腾讯会议：708-707-724

报告摘要：In this talk, we survey some of the latest results on spectral extrema of graphs with given size and forbidden subgraphs. We mainly introduce some new results on the maximum spectral radii of $H$-free graphs with given size, where a forbidden subgraph $H$ is a complete graph, a cycle, a theta graph, a fan graph, a wheel graph, a complete bipartite graph, a book or a friendship graph, respectively. In addition, let $H_7$ denote the $7$-vertex fan graph consisting of a $6$-vertex path plus a vertex adjacent to each vertex of the path. Let $K_3\vee \frac{m-3}{3}K_1$ be the graph obtained by joining each vertex of a triangle $K_3$ to $\frac{m-3}{3}$ isolated vertices.We prove that if $G$ is an $H_{7}$-free graph with size $m\geq 33$, then the spectral radius $\rho(G)\leq 1+\sqrt{m-2}$, equality holds if and only if $G\cong K_3 \vee \frac{m-3}{3}K_1$ (possibly, with some isolated vertices).

报告人简介：王力工，西北工业大学教授、博士生导师，荷兰特文特大学博士，主要从事图谱理论、有向图与超图的谱性质、整图的刻画、图的Turán数、图的Gallai-Ramsey数等研究，在JGT、DM、DAM等国际期刊上发表论文160多篇，主持国家自然科学基金多项，2025年获陕西高等学校科学技术研究优秀成果一等奖。

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