Mahler's Problem on Liouville Numbers II. Rational Maps
Abstract
In 1984, Mahler asked which analytic functions map the set โ of Liouville numbers into itself. In the first paper of this series, we proved that every real-analytic solution on an open interval is the restriction of a real rational function. We now identify a canonical subfield ๐ of โ such that, for every nonconstant Rโโ(X) and every nonempty open interval I in its domain, R(Iโฉโ)โโ if and only if R is defined over ๐ and Rโ1(โ)โฉ Iโฉโ=โ . The weaker inclusion R(Iโฉโ)โโโชโ holds if and only if R is defined over ๐. If R is not defined over ๐, every such interval contains a Cantor set of Liouville numbers whose images under R are irrational and have irrationality exponents bounded by a constant depending only on R. We also construct continuum many positive strong Liouville numbers ฯ for which ฯXm preserves โ for every mโฅ2, with all nonzero rational fibers consisting of Um-numbers.
Related
- On Mahler U-numbers under rational maps
- Smooth Diffeomorphisms and Mahler's Problem on Liouville Numbers
- Arithmetic Rigidity of Analytic Functions and Mahler's Problem on Liouville Numbers
- Formal solution and strong asymptotic expansion of some initial value problem in two complex time variables, infinite order irregular singularities and Mahler transforms
- The Tutte embedding of tree-weighted planar maps converges to Liouville quantum gravity
BibTeX
@misc{marques2026mahlers,
title = {{Mahler's Problem on Liouville Numbers II. Rational Maps}},
author = {Diego Marques},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.07177},
eprint = {2611.07177},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.07177},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Mahler's Problem on Liouville Numbers II. Rational Maps
AU - Diego Marques
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.07177
UR - https://arxiv.org/abs/2611.07177
AB - In 1984, Mahler asked which analytic functions map the set โ of Liouville numbers into itself. In the first paper of this series, we proved that every real-analytic solution on an open interval is the restriction of a real rational function. We now identify a canonical subfield ๐ of โ such that, for every nonconstant Rโโ(X) and every nonempty open interval I in its domain, R(Iโฉโ)โโ if and only if R is defined over ๐ and R^โ1(โ)โฉ Iโฉโ=โ
. The weaker inclusion R(Iโฉโ)โโโชโ holds if and only if R is defined over ๐. If R is not defined over ๐, every such interval contains a Cantor set of Liouville numbers whose images under R are irrational and have irrationality exponents bounded by a constant depending only on R. We also construct continuum many positive strong Liouville numbers ฯ for which ฯX^m preserves โ for every mโฅ2, with all nonzero rational fibers consisting of U_m-numbers.
ER -