The embedding problem in topological dynamics and Takens' theorem

TL;DR

This paper establishes embedding results for $bZ^k$-actions with low mean dimension, provides a detailed proof of Takens' theorem for $bZ$-actions, and confirms a conjecture in a generic setting.

Contribution

It introduces new embedding theorems for $bZ^k$-actions with low mean dimension and offers a comprehensive proof of Takens' theorem for $bZ$-actions.

Findings

Embedding of $bZ^k$-actions with mean dimension less than $D/2$ into shift spaces.

Complete proof of Takens' embedding theorem with continuous observable for $bZ$-actions.

Validation of the Lindenstrauss--Tsukamoto conjecture for generic $bZ$-actions.

Abstract

We prove that every $\mathbb{Z}^{k}$-action $(X,\mathbb{Z}^{k},T)$ of mean dimension less than $D/2$ admitting a factor $(Y,\mathbb{Z}^{k},S)$ of Rokhlin dimension not greater than $L$ embeds in $(([0,1]^{(L+1)D})^{\mathbb{Z}^{k}}\times Y,\sigma\times S)$, where $D\in\mathbb{N}$, $L\in\mathbb{N}\cup\{0\}$ and $\sigma$ is the shift on the Hilbert cube $([0,1]^{(L+1)D})^{\mathbb{Z}^{k}}$; in particular, when $(Y,\mathbb{Z}^{k},S)$ is an irrational $\mathbb{Z}^{k}$-rotation on the $k$-torus, $(X,\mathbb{Z}^{k},T)$ embeds in $(([0,1]^{2^kD+1})^{\mathbb{Z}^k},\sigma)$, which is compared to a previous result by the first named author, Lindenstrauss and Tsukamoto. Moreover, we give a complete and detailed proof of Takens' embedding theorem with a continuous observable for $\mathbb{Z}$-actions and deduce the analogous result for $\mathbb{Z}^{k}$-actions. Lastly, we show that the Lindenstrauss--Tsukamoto conjecture for $\mathbb{Z}$-actions holds generically, discuss an analogous conjecture for $\mathbb{Z}^{k}$-actions appearing in a forthcoming paper by the first two authors and Tsukamoto and verify it for $\mathbb{Z}^{k}$-actions on finite dimensional spaces.