# MATH Seminar

Title: Stability and applications of quadrilaterals
Seminar: Combinatorics
Speaker: Jie Ma of The University of Science and Technology of China
Contact: Dwight Duffus, dwightduffus@emory.edu
Date: 2019-09-30 at 4:00PM
Venue: MSC E406
Abstract:
A famous theorem of Furedi states that for any integer $q \geq 15$, any $C_4$-free graph on $q^2+q+1$ vertices has at most $q(q+1)^2/2$ edges. It is well-known that this bound is tight for infinitely many integers $q$, by polarity graphs constructed from finite projective planes. In this talk, we will present a stability result of Furedi's theorem and then discuss its applications on extremal numbers of $C_4$. Joint work with Jialin He and Tianchi Yang.