English

Borel sets which are null or non-$\sigma$-finite for every translation invariant measure

Classical Analysis and ODEs 2011-09-27 v1

Abstract

We show that the set of Liouville numbers is either null or non-σ\sigma-finite with respect to every translation invariant Borel measure on \RR\RR, in particular, with respect to every Hausdorff measure \iHg\iH^g with gauge function gg. This answers a question of D. Mauldin. We also show that some other simply defined Borel sets like non-normal or some Besicovitch-Eggleston numbers, as well as all Borel subgroups of \RR\RR that are not FσF_\sigma possess the above property. We prove that, apart from some trivial cases, the Borel class, Hausdorff or packing dimension of a Borel set with no such measure on it can be arbitrary.

Keywords

Cite

@article{arxiv.1109.5309,
  title  = {Borel sets which are null or non-$\sigma$-finite for every translation invariant measure},
  author = {Márton Elekes and Tamás Keleti},
  journal= {arXiv preprint arXiv:1109.5309},
  year   = {2011}
}