报告人：陈耀俊 教授

报告时间：2017年3月18日10:30--11:30

报告地点：逸夫楼701

报告摘要：A fractional coloring of a graphGis that we assign a nonnegative weight to each independent set inG, such that for each vertexvthe sum of the weights of the independent sets containingvis 1. The least sum of these weights is called the fractional chromatic number ofG, denoted by χ*(G). Recently, Steinberg conjecture is disproved. It has been proved that every planar graph without 4-7-cycles is 3-colorable. Thus, one may ask whether every planar graph without 4-6-cycles is 3-colorable. In this talk, we will show that every planar graph without 4- and 6-cycles are 7/2-colorable and our result provides some support for the truth of this question.

报告人简介：

陈耀俊，南京大学数学系教授，博士生导师，中国运筹学会第九届、第十届理事。2000年7月在中国科学院数学与系统科学研究院获理学博士学位；2000.7-2002.6在南京大学数学系从事博士后研究工作；2003.9-2005.8在香港理工大学商学院物流系从事博士后研究工作；目前主要从事图中特定子图结构、Ramsey 数以及编码理论、理论计算机与组合图论交叉问题的研究。近些年主持国家自然科学基金多项，在国内外专业学术杂志上发表多篇研究论文，其中50余篇发表在SCI检索源期刊上。