报告人: Prof. Qing Xiang (向青)(University of Delaware)

时间：2015年4月13日上午10：00-11：00

地点：维格堂113
 
报告摘要
  Let X be a finite set and let F be a family of subsets of X. The (usual) incidence matrix of F with respect to X is a matrix whose columns are indexed by the elements of X, whose rows are indexed by the elements of F, and the (A, x) entry of the matrix is 1 if x∈A, 0 otherwise, where A∈F and x∈X. Higher incidence matrices are defined in a similar way except that the columns of these matrices are indexed by subsets of X of fixed size greater than one. We will discuss properties of these matrices, and show how to use these matrices to prove theorems in extremal combinatorics. The talk should be understandable by any one with some basic knowledge in linear algebra.
 
报告人简介
 
向青博士现为美国特拉华大学教授、国家海外杰出青年科学基金获得者、国际组合数学及其应用协会Fellow。主要研究方向为组合数学，擅长于使用深刻的代数和数论工具来研究组合设计，有限几何，编码和加法组合中的问题。美国Math. Reviews对他的工作评论认为“的确非常优美”（indeed very elegant）。现为国际组合数学界权威SCI期刊《The Electronic Journal of Combinatorics》主编，同时担任SCI期刊《Journal of Combinatorial Designs》、《Designs, Codes and Cryptography》、《Journal of Combinatorics and Number Theory》的编委。曾被授予由国际组合数学及其应用协会颁发的杰出青年学术成就奖—“Kirkman Medal”。