题目：The signed graphs with symmetric spectra
时间：3月31日（周五）下午15:00-17:00
地点：教16，311会议室
主讲人：黄琼湘 教授
人物简介：
黄琼湘，新疆大学数学与系统科学学院教授、博士生导师，主要研究领域为图论、代数图论、图谱理论。主持多项国家自然科学基金项目， 参加国家自然科学基金重点项目。在J.Combin.Theory Ser. B、J. Algebraic Algebra、Discrete Math.、 Linear Algebra Appl.等国内外重要专业期刊发表论文140多篇。获新疆维吾尔自治区科技进步奖二等奖。
报告摘要：
It is well known that a graph $G$ has a symmetric spectrum if and only if it is bipartite, a signed graph $\Gamma=(G,\sigma)$ has a symmetric spectrum if $G$ is bipartite. However, there exists a spectrally symmetric signed graph $\Gamma=(G,\sigma)$ such that $G$ is not bipartite. In this paper, we focus to characterize the signed graphs with symmetric spectra. Some necessary and (or) sufficient conditions for spectrally symmetric signed graphs are given. Moreover, some methods to construct signed graphs with symmetric spectra are found and infinite families of these signed graphs are produced. Particularly, spectrally symmetric signed graphs of some classes are completely determined.