When a finite group freely acts on a topological space, we can define its index and coindex. They roughly measure the size of the given action. We explore the interaction between this index theory and topological dynamics. Given a fixed-point free dy
namical system, the set of $p$-periodic points admits a natural free action of $mathbb{Z}/pmathbb{Z}$ for each prime number $p$. We are interested in the growth of its index and coindex as $pto infty$. Our main result shows that there exists a fixed-point free dynamical system having the divergent coindex sequence. This solves a problem posed by [TTY20].
We study the problem of embedding arbitrary $mathbb{Z}^k$-actions into the shift action on the infinite dimensional cube $left([0,1]^Dright)^{mathbb{Z}^k}$. We prove that if a $mathbb{Z}^k$-action satisfies the marker property (in particular if it is
a minimal system without periodic points) and if its mean dimension is smaller than $D/2$ then we can embed it in the shift on $left([0,1]^Dright)^{mathbb{Z}^k}$. The value $D/2$ here is optimal. The proof goes through signal analysis. We develop the theory of encoding $mathbb{Z}^k$-actions into band-limited signals and apply it to proving the above statement. Main technical difficulties come from higher dimensional phenomena in signal analysis. We overcome them by exploring analytic techniques tailored to our dynamical settings. The most important new idea is to encode the information of a tiling of the Euclidean space into a band-limited function which is constructed from another tiling.
