Reverse Iterated Function Systems: Density, Dimensions, and $p$-adic Extension

Fuente: arXiv
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Main Authors: Miao, Junjie, Xu, Minghui
Format: Preprint
Published: 2026
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author Miao, Junjie
Xu, Minghui
author_facet Miao, Junjie
Xu, Minghui
contents In 1996, Strichartz introduced reverse iterated function systems (RIFS) $\mathcal{F}=\{f_i(x)=r_i x+b_i\}_{i=1}^m$ of expanding mappings on $\mathbb{Z}$ and left the determination of the general dimension formulas of invariant sets as an open problem. In this paper we study the topological and geometric properties as well as the dimensions of the forward orbits generated by such systems, thereby providing a complete solution. We first work in a general locally compact complete metric space to show that the non-empty invariant sets of $\mathcal{F}$ are unions of forward orbits, along with giving necessary and sufficient conditions for their existence. Specialising to the RIFS $\mathcal{F}$ on $\mathbb{R}$, we determine the upper and lower mass dimensions, the Beurling dimension, and the discrete Hausdorff dimension of its forward orbits and invariant sets. Moreover, we establish a fundamental connection with the box-counting and similarity dimensions of the attractor generated by the dual contractive IFS $\mathcal{F}^{-1}=\{f_i^{-1}(x)=r_i^{-1}(x-b_i)\}_{i=1}^m$. Under the assumptions that the orbit is non-overlapping and uniformly discrete, renewal theory yields the precise asymptotic central density: in the non-arithmetic case it converges to an explicitly computable constant, while in the arithmetic case it approaches a multiplicatively periodic function. Finally, an analogous treatment is given for $p$-adic systems, where the mass dimension of a forward orbit equals the $p$-adic box dimension of the corresponding $p$-adic attractor.
format Preprint
id arxiv_https___arxiv_org_abs_2605_13085
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reverse Iterated Function Systems: Density, Dimensions, and $p$-adic Extension
Miao, Junjie
Xu, Minghui
Dynamical Systems
Functional Analysis
In 1996, Strichartz introduced reverse iterated function systems (RIFS) $\mathcal{F}=\{f_i(x)=r_i x+b_i\}_{i=1}^m$ of expanding mappings on $\mathbb{Z}$ and left the determination of the general dimension formulas of invariant sets as an open problem. In this paper we study the topological and geometric properties as well as the dimensions of the forward orbits generated by such systems, thereby providing a complete solution. We first work in a general locally compact complete metric space to show that the non-empty invariant sets of $\mathcal{F}$ are unions of forward orbits, along with giving necessary and sufficient conditions for their existence. Specialising to the RIFS $\mathcal{F}$ on $\mathbb{R}$, we determine the upper and lower mass dimensions, the Beurling dimension, and the discrete Hausdorff dimension of its forward orbits and invariant sets. Moreover, we establish a fundamental connection with the box-counting and similarity dimensions of the attractor generated by the dual contractive IFS $\mathcal{F}^{-1}=\{f_i^{-1}(x)=r_i^{-1}(x-b_i)\}_{i=1}^m$. Under the assumptions that the orbit is non-overlapping and uniformly discrete, renewal theory yields the precise asymptotic central density: in the non-arithmetic case it converges to an explicitly computable constant, while in the arithmetic case it approaches a multiplicatively periodic function. Finally, an analogous treatment is given for $p$-adic systems, where the mass dimension of a forward orbit equals the $p$-adic box dimension of the corresponding $p$-adic attractor.
title Reverse Iterated Function Systems: Density, Dimensions, and $p$-adic Extension
topic Dynamical Systems
Functional Analysis
url https://arxiv.org/abs/2605.13085