English

Regularity of almost-surely injective projections in Euclidean spaces

Classical Analysis and ODEs 2023-06-27 v2

Abstract

In a previous work we proved that if a finite Borel measure μ\mu in a Euclidean space has Hausdorff dimension smaller than a positive integer kk, then the orthogonal projection onto almost every kk-dimensional linear subspace is injective on a set of full μ\mu-measure. In this paper we study the regularity of the inverses of these projections and prove that if μ\mu has a compact support XX such that (respectively) the Hausdorff, upper box-counting or Assouad dimension of XX is smaller than kk, then the inverse is (respectively) continuous, pointwise α\alpha-H\"older for some α(0,1)\alpha \in (0,1) or pointwise α\alpha-H\"older for every α(0,1)\alpha \in (0,1). The results generalize to the case of typical linear perturbations of Lipschitz maps and strengthen previously known ones in the lossless analog compression literature. We provide examples showing the sharpness of the statements. Additionally, we construct a non-trivial measure on the plane which admits almost-surely injective projections in every direction, and show that no homogeneous self-similar measure has this property.

Keywords

Cite

@article{arxiv.2301.11918,
  title  = {Regularity of almost-surely injective projections in Euclidean spaces},
  author = {Krzysztof Barański and Yonatan Gutman and Adam Śpiewak},
  journal= {arXiv preprint arXiv:2301.11918},
  year   = {2023}
}

Comments

v2: minor changes in the text. Examples showing sharpness of the results added to Section 6