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arXiv · 2603.11822

Badly approximable points on non-linear carpets

Roope Anttila·Jonathan M. Fraser·Henna Koivusalo
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Abstract

The badly approximable points in $\mathbb{R}^d$ are those for which Dirichlet's approximation theorem cannot be improved by more than a constant, that is, they are the points most difficult to approximate by rational vectors. An important problem in Diophantine approximation is to determine when the set of badly approximable points intersects a given set in full dimension. We find the first class of non-linear non-conformal attractors for which this full intersection property holds, thus answering a question of Das-Fishman-Simmons-Urba\'nski from 2019. We also provide a formula for the Hausdorff dimension of these attractors which is of independent interest.

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Roope Anttila, Jonathan M. Fraser, Henna Koivusalo. 2026-03-12. Badly approximable points on non-linear carpets. https://arxiv.org/abs/2603.11822

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