Dimensions of non-autonomous meromorphic functions of finite order

TL;DR

This paper investigates the dimensions of Julia and escaping sets for non-autonomous meromorphic functions of finite order, providing bounds, exact calculations for specific classes, and stability results under perturbations.

Contribution

It introduces methods to estimate and compute the Hausdorff dimensions of Julia and escaping sets for non-autonomous perturbations of meromorphic functions, including stability under small additive changes.

Findings

Lower bounds for Julia and escaping set dimensions established.

Exact Hausdorff dimensions calculated for specific function classes.

Stability of Hausdorff dimension under small additive perturbations demonstrated.

Abstract

In this paper we study two classes of meromorphic functions previously studied by Mayer, Kotus, and Urba\'nski. In particular we estimate a lower bound for the Julia set and the set of escaping points for non-autonomous additive and affine perturbations of functions from these classes. For particular classes we are able to calculate these dimensions exactly. In these cases, we are able to reinterpret our results to show that the Hausdorff dimension of the set of points in the Julia set which escape to infinity is stable under sufficiently small additive perturbations. We accomplish this by constructing non-autonomous iterated function systems, whose limit sets sit inside of the aforementioned non-autonomous Julia sets. We also give estimates for the eventual and eventual hyperbolic dimensions of these non-autonomous perturbations.