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New York Journal of Mathematics
Volume 30 (2024), 583-592

  

Nic Brody and Kasia Jankiewicz

Generalized residual finiteness of groups

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Published: April 15, 2024.
Keywords: residual finiteness, wreath products.
Subject [2020]: 20E26, 20F65.

Abstract
A countable group is residually finite if every nontrivial element can act nontrivially on a finite set. When a group fails to be residually finite, we might want to measure how drastically it fails - it could be that only finitely many conjugacy classes of elements fail to act nontrivially on a finite set, or it could be that the group has no nontrivial actions on finite sets whatsoever. We define a hierarchy of properties, and construct groups which become arbitrarily complicated in this sense.

Acknowledgements

We thank Martin Bridson, Marco Linton, and the anonymous referee for their helpful comments. The second author was supported by the NSF grants DMS-2203307 and DMS-2238198.


Author information

Nic Brody
Department of Mathematics
University of California
Santa Cruz, CA 95064, USA

nic@ucsc.edu

Kasia Jankiewicz
Department of Mathematics
University of California
Santa Cruz, CA 95064, USA

kasia@ucsc.edu