A measure-conjugacy invariant for free group actions (Q974069)

The paper is concerned with the problem of isomorphism of two dynamical systems. \textit{D. S. Ornstein} and \textit{B. Weiss} [J. Anal. Math. 48, 1--141 (1987; Zbl 0637.28015)] posed a question regarding the isomorphism of all Bernoulli shifts over a nonamenable group. Using a new measure-conjugacy invariant for actions of free groups, the author shows that two Bernoulli shifts over a finitely generated free group are measurably conjugate if and only if their base measures have the same entropy, thus answering the above question in the negative.