Quotients by countable subgroups are hyperfinite
Group Theory
2020-02-24 v2 Dynamical Systems
Logic
Abstract
We show that for any Polish group and any countable normal subgroup , the coset equivalence relation is a hyperfinite Borel equivalence relation. In particular, the outer automorphism group of any countable group is hyperfinite.
Cite
@article{arxiv.1909.08716,
title = {Quotients by countable subgroups are hyperfinite},
author = {Joshua Frisch and Forte Shinko},
journal= {arXiv preprint arXiv:1909.08716},
year = {2020}
}
Comments
7 pages; corrected implication (discrete -> smooth)