An ergodic system is dominant exactly when it has positive entropy

Abstract

AbstractAn ergodic dynamical system$\mathbf {X}$is called dominant if it is isomorphic to a generic extension of itself. It was shown by Glasneret al[On some generic classes of ergodic measure preserving transformations.Trans. Moscow Math. Soc.82(1) (2021), 15–36] that Bernoulli systems with finite entropy are dominant. In this work, we show first that every ergodic system with positive entropy is dominant, and then that if$\mathbf {X}$has zero entropy, then it is not dominant.