Badly approximable grids and k-divergent lattices

Fuente: arXiv
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Autori principali: Moshchevitin, Nikolay, Rao, Anurag, Shapira, Uri
Natura: Preprint
Pubblicazione: 2024
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author Moshchevitin, Nikolay
Rao, Anurag
Shapira, Uri
author_facet Moshchevitin, Nikolay
Rao, Anurag
Shapira, Uri
contents For an m by n real matrix A, we investigate the set of badly approximable targets for A as a subset of the m-torus. It is well known that this set is large in the sense that it is dense and has full Hausdorff dimension. We investigate the relationship between its measure and Diophantine properties of A. On the one hand, we give the first examples of a non-singular matrix A such that the set of badly approximable targets has full measure with respect to some non-trivial algebraic measure on the torus. For this, we use transference theorems due to Jarnik and Khintchine, and the parametric geometry of numbers in the sense of Roy. On the other hand, we give a novel Diophantine condition on A that slightly strengthens non-singularity, and show that under the assumption that A satisfies this condition, the set of badly approximable targets is a null-set with respect to any non-trivial algebraic measure on the torus. For this we use naive homogeneous dynamics, harmonic analysis, and a novel concept we refer to as mixing convergence of measures.
format Preprint
id arxiv_https___arxiv_org_abs_2402_00196
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Badly approximable grids and k-divergent lattices
Moshchevitin, Nikolay
Rao, Anurag
Shapira, Uri
Number Theory
Dynamical Systems
For an m by n real matrix A, we investigate the set of badly approximable targets for A as a subset of the m-torus. It is well known that this set is large in the sense that it is dense and has full Hausdorff dimension. We investigate the relationship between its measure and Diophantine properties of A. On the one hand, we give the first examples of a non-singular matrix A such that the set of badly approximable targets has full measure with respect to some non-trivial algebraic measure on the torus. For this, we use transference theorems due to Jarnik and Khintchine, and the parametric geometry of numbers in the sense of Roy. On the other hand, we give a novel Diophantine condition on A that slightly strengthens non-singularity, and show that under the assumption that A satisfies this condition, the set of badly approximable targets is a null-set with respect to any non-trivial algebraic measure on the torus. For this we use naive homogeneous dynamics, harmonic analysis, and a novel concept we refer to as mixing convergence of measures.
title Badly approximable grids and k-divergent lattices
topic Number Theory
Dynamical Systems
url https://arxiv.org/abs/2402.00196