# Assaf Rinot: Chromatic number of graphs — large gaps

11/January/2013, 13:30–15:00
Fields institute,Room 230

Speaker: Assaf Rinot

Title: Chromatic number of graphs — large gaps

Abstract: We shall present a construction of graphs of large size and large chromatic number whose any smaller subgraphs are countably chromatic.
The construction builds on our notion of Ostaszewski square.
It follows that if the covering lemma holds, and $\kappa$ is the successor of a strong limit singular cardinal, then there exists a graph of size and chromatic number $\kappa$, whose all subgraphs of size $<\kappa$ are countably chromatic.