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Published October 2017 | public
Journal Article

On the classification problem of free ergodic actions of nonamenable groups

Abstract

We show that, for any countable discrete nonamenable group Γ, the relations of conjugacy, orbit equivalence, stable orbit equivalence, von Neumann equivalence, and stable von Neumann equivalence of free ergodic pmp actions of Γ on the standard atomless probability space are not Borel. This answers a question of Kechris.

Additional Information

© 2017 Académie des sciences. Published by Elsevier Masson SAS. Received 30 July 2017, Accepted 3 October 2017, Available online 17 October 2017. Partially funded by SFB878 Groups, Geometry and Actions, and by a postdoctoral fellowship from the Humboldt Foundation. Partially supported by the NSF Grant DMS-1600186.

Additional details

Created:
August 19, 2023
Modified:
October 17, 2023