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Math Colloquium
Justin Moore
Cornell
Title: Amenability and Ramsey Theory

Abstract: Refreshments at 4:00, WeH 6220.

In 2005, Kechris, Pestov and Todorcevic proved a result which essentially equates the study of the extreme amenability of automorphism groups of countable structures with structural Ramsey theory. Here extreme amenability is the assertion that every continuous action of the group on a compact space has a fixed point. It turns out that this result can be adapted to characterize amenability as well, yielding a new form of structural Ramsey theory which is not yet well understood. Through this language, the amenability problem for $R$. Thompson's group $F$ becomes a non associative analog of Hindman's theorem.

Date: Friday, December 2, 2011
Time: 4:30 pm
Location: Wean Hall 7500
Submitted by:  Leoni