English

Dimension of diagonal self-affine measures with exponentially separated projections

Dynamical Systems 2025-02-14 v2

Abstract

Let μ \mu be a self-affine measure associated with a diagonal affine iterated function system (IFS) Φ={(x1,,xd)(ri,1x1+ti,1,,ri,dxd+ti,d)}iΛ \Phi = \{ (x_{1}, \ldots, x_{d}) \mapsto ( r_{i, 1}x_{1} + t_{i,1}, \ldots, r_{i,d}x_{d} + t_{i,d}) \}_{i\in\Lambda} on Rd \mathbb{R}^{d} and a probability vector p=(pi)iΛ p = (p_{i})_{i\in\Lambda}. For 1jd 1 \leq j \leq d , denote the j j -th the Lyapunov exponent by χj:=iΛpilogri,j \chi_{j} := \sum_{i\in\Lambda} - p_{i} \log | r_{i,j} |, and define the IFS induced by Φ \Phi on the jj-th coordinate as Φj:={xri,jx+ti,j}iΛ \Phi_{j} := \{ x \mapsto r_{i,j}x + t_{i,j}\}_{i\in\Lambda}. We prove that if χj1χj2 \chi_{j_{1}} \neq \chi_{j_{2}} for 1j1<j2d 1 \leq j_{1} < j_{2} \leq d , and Φj \Phi_{j} is exponentially separated for 1jd 1 \leq j \leq d , then the dimension of μ \mu is the minimum of d d and its Lyapunov dimension. This confirms a conjecture of Rapaport by removing the additional assumption that the linear parts of the maps in Φ \Phi are contained in a 1-dimensional subgroup. One of the main ingredients of the proof involves disintegrating μ \mu into random measures with convolution structure. In the course of the proof, we establish new results on dimension and entropy increase for these random measures.

Keywords

Cite

@article{arxiv.2501.17378,
  title  = {Dimension of diagonal self-affine measures with exponentially separated projections},
  author = {Zhou Feng},
  journal= {arXiv preprint arXiv:2501.17378},
  year   = {2025}
}

Comments

47 pages, added Corollaries 1.9 and 1.10, main result unchanged