20220429 马杰 Extremal graphs of four-cycles

报告题目: Extremal graphs of four-cycles

报告人：马杰 教授， 中国科学技术大学

时间：2022-4-29 （周五） 10：00-11：00

腾讯会议：960-560-816

报告摘要:  In extremal graph theory one is interested in the realtions between various graph invariants. Given a property P and an invariant u for a family F of graphs, we wish to determine the maximum value of u(G) among all graphs G in F satisfying the property P. The optimial value u(G) is called the extremal number and the graphs attaining this value are called extremal graphs.  A principal example of such an extremal problem is the so-called Turan type problem, initiated by Hungarian mathematicians Turan and Erdos in 1940s. In this talk, we will discuss some recent exact results on extremal graphs of four-cycles and a related conjecture of Erdos-Simonovits.