| Résume | Several recent methods for proving pointwise ergodic theorems for pmp actions of free groups critically use weak mixing properties of Markov measures on the boundary of a free group of finite rank. However, it was not known exactly which Markov measures are weak mixing. In joint work with Jenna Zomback, we give a complete characterization of such measures. This characterization goes through a new dynamical condition on the action that we call chaining, which is interesting in its own right. In fact, weak mixing is equivalent to chaining for all pmp actions of countable groups. |
