报告人：苗正科教授

 江苏师范大学

报告题目：LOCAL BASES OF PRIMITIVE NON-POWERFUL SIGNED DIGRAPHS

报告时间：2017年06月02日16:00

报告地点：海韵实验楼108

报告摘要：A signed digraph S is a digraph (permit loop but no multiple arc) where each arc of S is assigned a sign 1 or -1. For a primitive non-powerful signed digraph S of order n, the kth  local base of S,

denoted by lk(S), is de_ned byWang, Miao and Yan [ Discrete Math. 309(2009),748-754]. It is proved that lk(S)  2n2 - 4n + k + 2 for 1kn. A natural problem is that for all primitive and non-powerful signed digraphs of order n, how their kth local bases distribute in [1, 2 ,…,  2n2-4n+k+2]. From [ Discrete Math. 309(2009),748-754], it also follows that there is no sign digraph of order n  2 such that its kth (1k n-1) local base is in {2n2 - 6n+k+5, … , 2n2-4n+k}. We call such interval a “gap" for the kth local base, where 1k  n-1 and n  2. In this paper, we consider the local base of a primitive and non-powerful signed digraph. More “gaps" for the kth local base are shown, and the primitive non-powerful signed digraphs with the

kth local base in [2n2 -8n + 9 + k, …, 2n2- 4n + k] are completely characterized.

报告人简介：苗正科，南京大学博士，中国科学技术大学博士后。现任江苏师范大学数学学科教授、科技处处长。主要学术兼职有：中国运筹学会理事、中国运筹学会组合图论学分会副理事长、中国工业与应用数学学会图论组合及应用专业委员会常务委员、江苏省数学会副理事长、徐州市数学学会理事长。

主要研究组合矩阵的幂序列性质和图的着色，先后主持多项国家自然科学基金项目，在European Journal of Combinatorics、Journal of Graph Theory、Discrete Applied Mathematics和Discrete Mathematics等学术期刊上发表学术论文80余篇，获江苏省优秀教学成果奖二等奖2项。。

联系人：张莲珠教授

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