Dynamical sets whose union with infinity is connected

TL;DR

This paper investigates the topological connectedness of various sets associated with transcendental entire functions, providing conditions for connectedness, examples, and implications for the structure of escaping sets.

Contribution

It introduces new conditions for the connectedness of bounded orbit and bungee sets, and constructs an example function with all three sets connected, expanding understanding of their topological properties.

Findings

Conditions for connectedness of bounded orbit and bungee sets

An example function with all three sets connected

Identification of classes where escaping set is not a spider's web

Abstract

Suppose that $f$ is a transcendental entire function. In 2014, Rippon and Stallard showed that the union of the escaping set with infinity is always connected. In this paper we consider the related question of whether the union with infinity of the bounded orbit set, or the bungee set, can also be connected. We give sufficient conditions for these sets to be connected, and an example a transcendental entire function for which all three sets are simultaneously connected. This function lies, in fact, in the Speiser class. It is known that for many transcendental entire functions the escaping set has a topological structure known as a spider's web. We use our results to give a large class of functions in the Eremenko-Lyubich class for which the escaping set is not a spider's web. Finally we give a novel topological criterion for certain sets to be a spider's web.