报告题目：A class of symmetric graphs with 2-arc transitive quotients

报告简介：A graph X is G-symmetric if X admits G as a group of automorphisms acting transitively on the set of vertices and on the set of arcs of X, where an arc is an ordered pair of adjacent vertices. In the case when G is imprimitive on the vertex set V(X) of X, namely when V(X) admits a nontrivial G-invariant partition B, the quotient graph X_B of X is always G-symmetric. We obtain necessary conditions for X_B to be (G, 2)-arc transitive in the case when v-k is an odd prime p, where v is the block size of B and k is the number of vertices in a block having neighbours in a fixed adjacent block. We prove further that if p=3 or 5 then these necessary conditions are essentially sufficient for X_B to be (G, 2)-arc transitive.

报告人：许光俊，遵义师范学院，美国《数学评论》评论员；兼任《Discrete Mathematics》、《Discrete Applied Mathematics》、《Information Processing Letters》等国际学术期刊审稿人。市政协常委；贵州留学人员联谊会•贵州欧美同学会遵义分会副会长。曾获得墨尔本大学博士全额奖学金项目，主持国家自然科学基金、省教育厅项目各一项。

报告时间：2021年3月22日（星期一）下午 3:40-5:00.

报告地点：腾讯会议，ID： 163 506 159

主办单位：扬州大学数学科学学院

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