English

Zero entropy is generic

Dynamical Systems 2016-05-20 v2

Abstract

Dan Rudolph showed that for an amenable group Γ\Gamma, the generic measure-preserving action of Γ\Gamma on a Lebesgue space has zero entropy. Here this is extended to nonamenable groups. In fact, the proof shows that every action is a factor of a zero entropy action! This uses the strange phenomena that in the presence of nonamenability, entropy can increase under a factor map. The proof uses Seward's recent generalization of Sinai's Factor Theorem, the Gaboriau-Lyons result and my theorem that for every nonabelian free group, all Bernoulli shifts factor onto each other.

Keywords

Cite

@article{arxiv.1603.02621,
  title  = {Zero entropy is generic},
  author = {Lewis Bowen},
  journal= {arXiv preprint arXiv:1603.02621},
  year   = {2016}
}

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R2 v1 2026-06-22T13:06:39.575Z