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韩国Yang Jae Young博士学术报告会

  发布日期:2016-12-27  浏览量:589


报告题目: Some classes of graphs represented by Hoffman graphs

报 告 人:Yang Jae Young(韩国浦项科技大学, 博士)

报告时间: 201714(周三)下午16:00-17:00

报告地点: 磬苑校区澳门赌搏网站大全H306

报告摘要: In 1977, Hoffman gave a characterization of graphs with smallest eigenvalue greater than He showed that there exists a positive integer    such that if a graph   has smallest eigenvalue greater than and minimal degree at least , then   is a generalized line graph.  

    In 1995, Woo and Neumaier defined the concept of Hoffman graphs, which formulates the main idea of Hoffman. A Hoffman graph h is a pair , where  is a graph and :  is a labeling map on , such that any two vertices with label  are not adjacent and every vertex with label  has at least one neighbor with label s. They also gave a characterization of graphs with smallest eigenvalue greater than , where  is the smallest root of . This class of graphs is represented by four Hoffman graphs.  

    Our main goal is to understand the structure of graphs with smallest eigenvalue at least 3. We find a good generalization of Hoffman’s  result in 1977, which proides new classes of graphs containing the Johnson graph , the Hamming graph , and the 2-clique extension of the -grid.

 

 

专家概况: Yang Jae Young, 2009年2月在浦项科技大学数学系本科毕业,2009年3月至今,在浦项科技大学完成硕士学位并攻读博士学位。在“Electron. J. Combin.”, “Linear Algebra Appl.”上发表论文数篇

 

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