学术报告

题      目： An extremal problem on digraphs

报  告  人：黄泽军   教授  (邀请人：尤利华 )

                                    深圳大学

时      间：4月11日  16：30-18：30

腾 讯 会 议 号：797249852

报告人简介:

       黄泽军，深圳大学副教授、博士生导师，研究兴趣包括图论和组合矩阵论。已在Discrete Math.、Linear Algebra Appl.、 SIAM J. Matrix Anal. Appl. 等期刊发表论文30余篇，担任学术期刊Electronic Journal of Linear Algebra 编委，2019年入选深圳市高层次专业人才。

摘      要：

      Let $n$ and $k$ be integers larger than or equal to 2. Let $D$ be a simple digraph on $n$ vertices such that $D$ does not contain two distinct walks of length $k$ with the same initial vertex and the same terminal vertex. What is the maximum size of $D$? This problem is equivalent to the following: what is the maximum number of ones in an $n\times n$ matrix $A$ such that both $A$ and $A^k$ are 0-1 matrices? In this talk, we will present the solution to this problem.
This talk is based on joint work with Zhenhua Lyu, Pu Qiao and Xingzhi Zhan.