报告题目1：The characteristic and permanentalpolynomials of graphsand reconstruction

报告人：王卫教授，西安交通大学

报告时间：2026年5月16日（周六）14:00-17:00

报告地点：20-202

报告摘要：The characteristic (permanental)polynomials of graphs are important invariants of graphs, which have been studiedextensively in recent years. In this talk, we present some new results on theseinvariants.Some applications in the polynomial reconstruction problem are alsoprovided.

报告人简介：王卫，西安交通大学数学与统计学院教授、博士生导师。主要研究领域为代数图论与组合最优化。在图谱理论的研究中对图的广义谱刻画问题做出了一些原创性的工作，在组合优化领域中对一些NP-困难组合优化问题设计出了一些好的近似算法。在J. Combin. Theory, Ser B, European J. Combin. 以及IEEE/ACMTransactions系列等组合图论刊物上发表研究论文100余篇，主持（完成）国家自然科学基金面上项目多项。目前担任中国运筹学会图论与组合分会常务理事、陕西省工业与应用数学学会理事长及国际刊物《Linear Algebra Appl.》、《Discrete Mathematics, Algorithms and Applications》编委等。

报告题目2：The distance spectral radius of connected graphs of fixed size

报告人：周波教授，华南师范大学

报告时间：2026年5月16日（周六）14:00-17:00

报告地点：20-202

报告摘要：Let $m$ be a positive integer. Brualdi and Hoffman proposed theproblem to determine the graphs with maximum adjacency spectral radius in a given graph class and they posed a conjecture for the class ofconnected graphs with given size $m$. After partial results due to Friedland and Stanley, Rowlinson completely confirmed the conjecture. The distance spectral radius of a connected graph is the largest eigenvalue of its distance matrix. We investigate the problem to determine the connected graphs with minimum distance spectral radius in the class of connected graphs with size $m$. Given $m$, there is exactly one positive integer $n$ such that ${n-1\choose 2}<m\leq {n\choose="" 2}$. By existing results and experiments, the graphs with maximum adjacency spectral radius happen to be the graphs with minimum distance spectral radius over many classes of graphs.  However, this is not the case in the class of connected graphs with size $m$ for $s<n-2$, where $s=m-{n-1 \choose 2}$. This is joint work with Hongying Lin.

报告人简介：周波，1995年7月至今在华南师范大学数学系（数学科学学院）工作。主要兴趣包括组合矩阵论、代数图论，近年来主要工作在图与超图谱理论方面，与合作者发表论文100篇。

报告题目3：B-coloring of planar graphs

报告人：王艺桥教授，北京工业大学

报告时间：2026年5月16日（周六）14:00-17:00

报告地点：20-202

报告摘要：A proper edgecoloring of a graph G is called a B-coloring if every 4-cycle of G is colored with four distinct colors. Let qB(G) denote the minimum number of colors required for a B-coloring of G. In this talk, we prove the following results:(1) Let Gbe a planar graph. Then qB(G)≤2Δ+6; furthermore, qB(G)≤2Δ+4 if Δ≥12; and qB(G)≤2Δ if Δ≥38.(2) Every outerplanar graph G with Δ≥7 satisfiesqB(G)=Δ.This solves the conjecture raised by Gyárfás et al. in [Proper edgecoloring of planar graphs with rainbow C4-s, J. Graph Theory, 107(2024), 833-846.]

报告人简介：王艺桥，北京工业大学数学统计学与力学学院教授、博士生导师，国家级青年人才。主要研究领域是图的结构与图的染色。现任中国运筹学会图论组合分会常务理事兼副秘书长，中国数学会组合数学与图论专委会委员，中国工业与应用数学会图论组合及应用专委会委员。主持国家自然科学基金面上项目2项、青年项目1项，参与中韩国际合作与交流项目1项。在J. Graph Theory, SIAM J. Discrere Math., European J. Combin.等期刊上发表SCI论文90余篇。获教育部自然科学二等奖1项，1篇论文获中国运筹学会“图论组合分会青年论文奖”一等奖。

邀请人：数学研究所