The descriptive look at the size of subsets of groups
General Topology
2017-03-02 v1
Abstract
We explore the Borel complexity of some basic families of subsets of a countable group (large, small, thin, sparse and other) defined by the size of their elements. Applying the obtained results to the Stone-\v{C}ech compactification of , we prove, in particular, that the closure of the minimal ideal of is of type .
Keywords
Cite
@article{arxiv.1703.00174,
title = {The descriptive look at the size of subsets of groups},
author = {Igor Protasov and Taras Banakh and Ksenia Protasova},
journal= {arXiv preprint arXiv:1703.00174},
year = {2017}
}