Entropic rates from eigenfunction structure for × 2 × 3
Abstract
In a companion article \cite{RJnodyn} the present authors proved a form of the Rudolph--Johnson theorem which is effective at finite resolution, bounding the low-frequency Fourier coefficients of a × 2 × 3-invariant measure by its normalized entropy. Here we read that bound in the other direction, as a constraint on eigenfunction behavior in potential counterexamples to Furstenberg's × 2 × 3 conjecture. We show that a near return of the coordinate function x ↦ e2πix to itself under the semigroup generated by $2$ and $3$ forces the resolution entropy to be small, and that adherence of the coordinate function to eigenfunctions of x ↦ 2x forces it to decay. These rates are explicit in the rate of adherence and in the arithmetic of the eigenvalues.
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BibTeX
@misc{burton2026entropic,
title = {{Entropic rates from eigenfunction structure for $\times 2 \times 3$}},
author = {Peter Burton and Kate Juschenko},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.04745},
eprint = {2610.04745},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.04745},
}
RIS
TY - UNPB
TI - Entropic rates from eigenfunction structure for × 2 × 3
AU - Peter Burton
AU - Kate Juschenko
PY - 2026
DA - 2026/10/03
PB - arXiv
DO - 10.48550/arxiv.2610.04745
UR - https://arxiv.org/abs/2610.04745
AB - In a companion article \cite{RJnodyn} the present authors proved a form of the Rudolph--Johnson theorem which is effective at finite resolution, bounding the low-frequency Fourier coefficients of a × 2 × 3-invariant measure by its normalized entropy. Here we read that bound in the other direction, as a constraint on eigenfunction behavior in potential counterexamples to Furstenberg's × 2 × 3 conjecture. We show that a near return of the coordinate function x ↦ e^2πix to itself under the semigroup generated by $2$ and $3$ forces the resolution entropy to be small, and that adherence of the coordinate function to eigenfunctions of x ↦ 2x forces it to decay. These rates are explicit in the rate of adherence and in the arithmetic of the eigenvalues.
ER -