Invariant random subgroups and action versus representation maximality
  We show that weak containment of free ergodic measure-preserving actions of $\mathbf{F}_\infty$ is not equivalent to weak containment of the corresponding Koopman representations. This result is based on the construction of an invariant random subgroup of $\mathbf{F}_\infty$ which is supported on the maximal actions. 
Peter J. Burton and Alexander S. Kechris
math.DS math.LO