English

Spiders' webs in the Eremenko-Lyubich class

Dynamical Systems 2025-05-13 v3 Complex Variables

Abstract

Consider the entire function f(z)=cosh(z)f(z)=\cosh(z). We show that the escaping set of this function - that is, the set of points whose orbits tend to infinity under iteration - has a structure known as a "spider's web". This disproves a conjecture of Sixsmith from 2020. In fact, we show that the "fast escaping set", i.e. the set of points whose orbits tend to infinity at an iterated exponential rate, is a spider's web. This answers a question of Rippon and Stallard from 2012. We also discuss a wider class of functions to which our results apply, and state some open questions.

Keywords

Cite

@article{arxiv.2410.20998,
  title  = {Spiders' webs in the Eremenko-Lyubich class},
  author = {Lasse Rempe},
  journal= {arXiv preprint arXiv:2410.20998},
  year   = {2025}
}

Comments

10 pages, to appear in Int. Math. Res. Not. V3: Author accepted manuscript; some clarifications and improvements to the exposition throughout

R2 v1 2026-06-28T19:37:59.469Z