Thursday February 9th at 4pm

said to be

An obvious example of a bull free graph is a graph with no triangle, or a graph with no

stable set of size three; but there are others. It turns out, however, that all bullfree

graphs can be built starting from graphs that belong to a few basic classes, and gluing

them together by certain operations; and this is the main topic of this talk. Using

this structure theorem, in joint work with S. Safra, we were able to prove that in every

bull free graph there is either a stable set or a clique containing at least