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Marstrand's projection theorem from $1954$ states that if $K \subset \mathbb{R}^{3}$ is an analytic set, then, for $\mathcal{H}^{2}$ almost every $e \in S^{2}$, the orthogonal projection $\pi_{e}(K)$ of $K$ to the line spanned by $e$ has…

Classical Analysis and ODEs · Mathematics 2021-07-05 Antti Käenmäki , Tuomas Orponen , Laura Venieri

In this paper we use the theory of computing to study fractal dimensions of projections in Euclidean spaces. A fundamental result in fractal geometry is Marstrand's projection theorem, which shows that for every analytic set E, for almost…

Computational Complexity · Computer Science 2021-11-15 Neil Lutz , D. M. Stull

We present strong versions of Marstrand's projection theorems and other related theorems. For example, if E is a plane set of positive and finite s-dimensional Hausdorff measure, there is a set X of directions of Lebesgue measure 0, such…

Metric Geometry · Mathematics 2015-11-19 Kenneth Falconer , Pertti Mattila

We study projections onto non-degenerate one-dimensional families of lines and planes in $\mathbb{R}^{3}$. Using the classical potential theoretic approach of R. Kaufman, one can show that the Hausdorff dimension of at most…

Classical Analysis and ODEs · Mathematics 2014-11-27 Katrin Fässler , Tuomas Orponen

Assuming $V=L$, we construct a plane set $E$ of Hausdorff dimension $1$ whose every orthogonal projection onto straight lines through the origin has Hausdorff dimension $0$. This is a counterexample to J. M. Marstrand's seminal projection…

Logic · Mathematics 2023-01-18 Linus Richter

We investigate variants of Marstrand's projection theorem that hold for sets of directions and classes of sets in $\mathbb{R}^2$. We say that a set of directions $D \subseteq\mathcal{S}^1$ is $\textit{universal}$ for a class of sets if, for…

Classical Analysis and ODEs · Mathematics 2025-03-25 Jacob B. Fiedler , D. M. Stull

Let $F \subset \mathbb{R}^{2}$, and let $\dim_{\mathrm{A}}$ stand for Assouad dimension. I prove that $\dim_{\mathrm{A}} \pi_{e}(F) \geq \min\{\dim_{\mathrm{A}} F,1\}$ for all $e \in S^{1}$ outside of a set of Hausdorff dimension zero. This…

Classical Analysis and ODEs · Mathematics 2020-05-13 Tuomas Orponen

We establish several optimal estimates for exceptional parameters in the projection of fractal measures: (1) For a parametric family of self-similar measures satisfying a transversality condition, the set of parameters leading to a…

Dynamical Systems · Mathematics 2025-10-09 Meng Wu

Intermediate dimensions were recently introduced to interpolate between the Hausdorff and box-counting dimensions of fractals. Firstly, we show that these intermediate dimensions may be defined in terms of capacities with respect to certain…

Classical Analysis and ODEs · Mathematics 2021-05-21 Stuart A. Burrell , Kenneth J. Falconer , Jonathan M. Fraser

Marstrand's celebrated projection theorem gives the Hausdorff dimension of the orthogonal projection of a Borel set in Euclidean space for almost all orthogonal projections. It is straightforward to see that sets for which the Fourier and…

Classical Analysis and ODEs · Mathematics 2024-06-21 Jonathan M. Fraser , Ana E. de Orellana

We establish a refinement of Marstrand's projection theorem for Hausdorff dimension functions finer than the usual power functions, including an analogue of Marstrand's Theorem for logarithmic Hausdorff dimension.

Metric Geometry · Mathematics 2018-12-17 Victor Beresnevich , Kenneth Falconer , Sanju Velani , Agamemnon Zafeiropoulos

$\Phi$-intermediate dimensions interpolate between Hausdorff and box-counting dimensions by restricting admissible coverings to scale windows of the form $[\Phi(r),r]$. Using a family of $\Phi$-dependent kernels, we develop a…

Metric Geometry · Mathematics 2026-04-17 Lara Daw , Najmeddine Attia

\emph{Fractal percolation} or \emph{Mandelbrot percolation} is one of the most well studied families of random fractals. In this paper we study some of the geometric measure theoretical properties (dimension of projections and structure of…

Dynamical Systems · Mathematics 2015-06-16 Michal Rams , Károly Simon

The point-to-set principle \cite{LutLut17} characterizes the Hausdorff dimension of a subset $E\subseteq\R^n$ by the \textit{effective} (or algorithmic) dimension of its individual points. This characterization has been used to prove…

Computational Complexity · Computer Science 2021-05-13 D. M. Stull

Let $0 \leq s \leq 1$ and $0 \leq t \leq 2$. An $(s,t)$-Furstenberg set is a set $K \subset \mathbb{R}^{2}$ with the following property: there exists a line set $\mathcal{L}$ of Hausdorff dimension $\dim_{\mathrm{H}} \mathcal{L} \geq t$…

Classical Analysis and ODEs · Mathematics 2025-03-31 Tuomas Orponen , Pablo Shmerkin

We prove a universal projection theorem, giving conditions on a parametrized family of maps $\Pi_\lambda : X \to \mathbb{R}^d$ and a collection M of measures on X under which for almost every $\lambda$ equality $\dim_H \Pi_\lambda \mu =…

Dynamical Systems · Mathematics 2025-09-24 Balázs Bárány , Károly Simon , Adam Śpiewak

Let $\gamma: [-1, 1]\to \mathbb{R}^n$ be a smooth curve that is non-degenerate. Take $m\le n$ and a Borel set $E\subset [0, 1]^n$. We prove that the orthogonal projection of $E$ to the $m$-th order tangent space of $\gamma$ at $\theta\in…

Classical Analysis and ODEs · Mathematics 2024-01-23 Shengwen Gan , Shaoming Guo , Hong Wang

Given a finite set $\mathcal{A} \subseteq \mathrm{SL}(2,\mathbb{R})$ we study the dimension of the attractor $K_\mathcal{A}$ of the iterated function system induced by the projective action of $\mathcal{A}$. In particular, we generalise a…

Dynamical Systems · Mathematics 2020-07-14 Argyrios Christodoulou , Natalia Jurga

In this paper we study the radial and orthogonal projections and the distance sets of the random Cantor sets $E\subset \mathbb{R}^2 $ which are called Mandelbrot percolation or percolation fractals. We prove that the following assertion…

Dynamical Systems · Mathematics 2013-06-18 Michal Rams , Károly Simon

We prove that for any $E\subset{\Bbb R}^2$, $\dim_{\mathcal{H}}(E)>1$, there exists $x\in E$ such that the Hausdorff dimension of the pinned distance set $$\Delta_x(E)=\{|x-y|: y \in E\}$$ is no less than…

Classical Analysis and ODEs · Mathematics 2019-11-06 Bochen Liu
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