Mathematical logic seminar - Mar 21 2017

Time: 3:30pm - 4:30 pm

Room: Wean Hall 8220

Speaker:     Dana Bartošová    
Department of Mathematical Sciences

Title: Freedom of action in combinatorial terms


A group acts freely on a compact Hausdorff space if all of its non-identity 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.