13
Sep
Title: Quadruple systems with independent neighborhoods
Speaker: Dhruv Mubayi (CMU)
When: September 13, 16:30-17:30pm
Where: WEH 5302 (all future talks will be held here)
Abstract:
What is the maximum number of edges in a k-uniform hypergraph on n vertices whose neighborhoods are all independent sets? When $k=2$ the answer is $n^2/4$ proved by Mantel in 1907. This was the first result in extremal graph theory. The next case $k=3$ was solved by Furedi-Pikhurko-Simonovits in 2003. I will present a proof for the case $k=4$. This is joint work with Zoltan Furedi and Oleg Pikhurko.
