Tight inclusions of C*-dynamical systems

Yair Hartman, Mehrdad Kalantar

Research output: Contribution to journalArticlepeer-review


We study a notion of tight inclusions of C *- and W *-dynamical systems, which is meant to capture a tension between topological and measurable rigidity of boundary actions. An important case of such inclusions is C (X) ⊂ L(X; ν) for measurable boundaries with unique stationary compact models. We discuss the implications of this phenomenon in the description of Zimmer amenable intermediate factors. Furthermore, we prove applications in the problem of maximal injectivity of von Neumann algebras.

Original languageEnglish
Pages (from-to)67-90
Number of pages24
JournalGroups, Geometry, and Dynamics
Issue number1
StatePublished - 1 Jan 2024


  • boundary actions
  • C*-dynamical systems

ASJC Scopus subject areas

  • Geometry and Topology
  • Discrete Mathematics and Combinatorics


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