Descriptive complexity in Cantor series
Abstract
A Cantor series expansion for a real number with respect to a basic sequence , where , is a representation of the form where . These generalize ordinary base expansions where . Ki and Linton showed that for ordinary base expansions the set of normal numbers is a -complete set, establishing the exact complexity of this set. In the case of Cantor series there are three natural notions of normality: normality, ratio normality,and distribution normality (these notions are equivalent for base expansions). We show that for any the set of distribution normal number is -complete, and if is -divergent (i.e., diverges) then the sets and of normal and ratio normal numbers are -complete. We further show that all five non-trivial differences of these sets are -complete if and is -divergent (the trivial case is ). This shows that except for the containment , these three notions are as independent as possible.
Keywords
Cite
@article{arxiv.2010.13947,
title = {Descriptive complexity in Cantor series},
author = {Dylain Airey and Steve Jackson and Bill Mance},
journal= {arXiv preprint arXiv:2010.13947},
year = {2020}
}
Comments
22 pages