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arXiv · 1609.08053

A proof of Furstenberg's conjecture on the intersections of $\times p$ and $\times q$-invariant sets

Meng Wu
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Abstract

We prove the following conjecture of Furstenberg (1969): if $A,B\subset [0,1]$ are closed and invariant under $\times p \mod 1$ and $\times q \mod 1$, respectively, and if $\log p/\log q\notin \mathbb{Q}$, then for all real numbers $u$ and $v$, $$\dim_{\rm H}(uA+v)\cap B\le \max\{0,\dim_{\rm H}A+\dim_{\rm H}B-1\}.$$ We obtain this result as a consequence of our study on the intersections of incommensurable self-similar sets on $\mathbb{R}$. Our methods also allow us to give upper bounds for dimensions of arbitrary slices of planar self-similar sets satisfying SSC and certain natural irreducible conditions.

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Meng Wu. 2016-09-26. A proof of Furstenberg's conjecture on the intersections of $\times p$ and $\times q$-invariant sets. https://arxiv.org/abs/1609.08053

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