Time:  3:30pm  4:30 pm 
Room: 
Wean Hall 8220

Speaker: 
Dana Bartošová Department of Mathematical Sciences CMU 
Title: 
Freedom of action in combinatorial terms

Abstract: 
A group acts freely on a compact Hausdorff space if all of its nonidentity elements act without fixed points. By Veech's theorem, every locally compact topological group admits a free action and the question arises to which other groups this property can be extended. On the other hand, elements of extremely amenable groups act with fixed points under any action but the opposite implication does not hold. We show a combinatorial reformulation of this property and ask how far it is from extreme amenability. 