Toronto Set Theory


Thompson's group is amenable

by Justin Moore | Cornell
Time: 11:00  (Friday, Sep. 07, 2012)
Location: FI230, Fields Institute, 222 College St
I will demonstrate that Thompson's group F is amenable. This will be done by exhibiting an idempotent measure on the free nonassociative groupoid on one generator. This in turn can be used to generalize Hindman's theorem to the setting of nonassociative operations.


Extreme amenability of abelian L0 groups

by Marcin Sabok | Impan
Time: 13:30  (Friday, Sep. 07, 2012)
Location: FI230, Fields Institute, 222 College St
Answering a question of Farah, Solecki and Pestov, we show that the group $L_0(\mu)$ is extremely amenable if and only if $\mu$ is a diffused submeasure. This provides a witness for a positive answer to the Glasner--Pestov problem, as it implies that $L_0(\mu)$ is extremely amenable if and only if it has no nontrivial characters. Given a submeasure $\mu$ on an algebra of subse

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