Countable Abelian Group Actions
and
Hyperfinite Equivalence Relations
Su Gao and Steve Jackson
Abstract
We prove that a Borel action of any countable abelian group gives rise to a hyperfinite equivalence relation.
Table of Contents
Preliminaries
Clopen marker sets
Regular marker regions
An application of regular marker regions
Orthogonal marker regions
Hyperfiniteness of F(Z<ω)
The non-free part
Actions of countable abelian groups
Continuous embeddings into E0
Open problems and further remarks