TY - JOUR
T1 - Badly approximable grids and k-divergent lattices
AU - Moshchevitin, Nikolay
AU - Rao, Anurag
AU - Shapira, Uri
N1 - Publisher Copyright: © 2024 The Author(s). Mathematika is copyright © University College London and published by the London Mathematical Society on behalf of University College London.
PY - 2024/7
Y1 - 2024/7
N2 - Let (Formula presented.) be a matrix. In this paper, we investigate the set (Formula presented.) of badly approximable targets for (Formula presented.), where (Formula presented.) is the (Formula presented.) -torus. It is well known that (Formula presented.) is a winning set for Schmidt's game and hence is a dense subset of full Hausdorff dimension. We investigate the relationship between the measure of (Formula presented.) and Diophantine properties of (Formula presented.). On the one hand, we give the first examples of a nonsingular (Formula presented.) such that (Formula presented.) has full measure with respect to some nontrivial 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 (Formula presented.) that slightly strengthens nonsingularity, and show that under the assumption that (Formula presented.) satisfies this condition, (Formula presented.) is a null-set with respect to any nontrivial algebraic measure on the torus. For this, we use naive homogeneous dynamics, harmonic analysis, and a novel concept that we refer to as mixing convergence of measures.
AB - Let (Formula presented.) be a matrix. In this paper, we investigate the set (Formula presented.) of badly approximable targets for (Formula presented.), where (Formula presented.) is the (Formula presented.) -torus. It is well known that (Formula presented.) is a winning set for Schmidt's game and hence is a dense subset of full Hausdorff dimension. We investigate the relationship between the measure of (Formula presented.) and Diophantine properties of (Formula presented.). On the one hand, we give the first examples of a nonsingular (Formula presented.) such that (Formula presented.) has full measure with respect to some nontrivial 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 (Formula presented.) that slightly strengthens nonsingularity, and show that under the assumption that (Formula presented.) satisfies this condition, (Formula presented.) is a null-set with respect to any nontrivial algebraic measure on the torus. For this, we use naive homogeneous dynamics, harmonic analysis, and a novel concept that we refer to as mixing convergence of measures.
UR - http://www.scopus.com/inward/record.url?scp=85197452630&partnerID=8YFLogxK
U2 - https://doi.org/10.1112/mtk.12262
DO - https://doi.org/10.1112/mtk.12262
M3 - مقالة
SN - 0025-5793
VL - 70
JO - Mathematika
JF - Mathematika
IS - 3
M1 - e12262
ER -