TURBULENCE, REPRESENTATIONS, AND TRACE-PRESERVING ACTIONS (2009)
David Kerr, Hanfeng Li, Mikaël Pichot
Abstract. We establish criteria for turbulence in certain spaces of C ∗-algebra representations and apply this to the problem of nonclassifiability by countable structures for group actions on a...
A note on Markov type constants ∗† (2008)
We prove that, if a geodesic metric space has Markov type 2 with constant 1, then it is an Alexandrov space of nonnegative curvature. The same technique provides a lower bound of the Markov type 2...
A note on Markov type constants ∗† (2008)
We prove that, if a geodesic metric space has Markov type 2 with constant 1, then it is an Alexandrov space of nonnegative curvature. The same technique provides a lower bound of the Markov type 2...
Uniform non-amenability, cost, and the first l^2-Betti number (2007)
Lyons, Russell, Pichot, Mikaël, Vassout, Stéphane
It is shown that $2\beta_1(\G)\leq h(\G)$ for any countable group $\G$, where $\beta_1(\G)$ is the first $\ell^2$-Betti number and $h(\G)$ the uniform isoperimetric constant. In particular, a...