Naively Haar null sets in Polish groups
Logic
2015-08-11 v1
Abstract
Let be a Polish group. We say that a set is Haar null if there exists a universally measurable set and a Borel probability measure such that for every we have . We call a set naively Haar null if there exists a Borel probability measure such that for every we have . Generalizing a result of Elekes and Stepr\=ans, which answers the first part of Problem FC from Fremlin's list, we prove that in every abelian Polish group there exists a naively Haar null set that is not Haar null.
Keywords
Cite
@article{arxiv.1508.02227,
title = {Naively Haar null sets in Polish groups},
author = {Márton Elekes and Zoltán Vidnyánszky},
journal= {arXiv preprint arXiv:1508.02227},
year = {2015}
}