On the topological pressure of axial product on trees
Jung-Chao Ban, Yu-Liang Wu
TL;DR
The paper addresses the problem of understanding the topological pressure for isotropic axial products of Markov subshifts on $d$-trees. It develops a pattern-distribution framework and a finite-k optimization $P^{(k)}(d,E)$, proving that the limiting pressure $P^{(\infty)}(d,E)$ is continuous and increasing in $d$, with asymptotic limits $\log \rho(E)$ and $\log r_E$ as $d\to1^+$ and $d\to\infty$, respectively. The authors transform the combinatorial problem using Stirling's approximation and KL-divergence, derive an explicit entropy-maximizing form for the optimizer, and establish convergence of $P^{(k)}(d,E)$ to $P^{(\infty)}(d,E)$ along with a rigorous monotonicity proof. They also provide numerical experiments on golden-mean tree-shifts to verify the theoretical results and demonstrate applicability to broader shift spaces. The work extends limiting pressure concepts to tree-shifts and offers a versatile framework for analyzing high-dimensional axial products through a variational, pattern-distribution lens.
Abstract
This article investigates the topological pressure of isotropic axial products of Markov subshifts on the $d$-tree. We show that the quantity increases with dimension $d$. To achieve this, we introduce the pattern distribution vectors and the associated transition matrices and partially transplant the large deviation theory to tree-shifts. Additionally, we apply our main result to a broader class of shift spaces, accompanied by numerical experiments for verification.
