English

Rational functions with identical measure of maximal entropy

Dynamical Systems 2014-09-29 v3

Abstract

We discuss when two rational functions ff and gg can have the same measure of maximal entropy. The polynomial case was completed by (Beardon, Levin, Baker-Eremenko,Schmidt-Steinmetz, etc., 1980s-90s), and we address the rational case following Levin-Przytycki (1997). We show: μf=μg\mu_f = \mu_g implies that ff and gg share an iterate (fn=gmf^n = g^m for some nn and mm) for general ff with degree d3d \geq 3. And for generic f\Ratd3f\in \Rat_{d\geq 3}, μf=μg\mu_f = \mu_g implies g=fng=f^n for some n1n \geq 1. For generic f\Rat2f\in \Rat_2, μf=μg\mu_f = \mu_g implies that g=fng= f^n or σffn\sigma_f\circ f^n for some n1n\geq 1, where σfPSL2(\C)\sigma_f\in PSL_2(\C) permutes two points in each fiber of ff. Finally, we construct examples of ff and gg with μf=μg\mu_f = \mu_g such that fnσgmf^n \neq \sigma\circ g^m for any σPSL2(\C)\sigma \in PSL_2(\C) and m,n1m,n\geq 1.

Keywords

Cite

@article{arxiv.1211.4303,
  title  = {Rational functions with identical measure of maximal entropy},
  author = {Hexi Ye},
  journal= {arXiv preprint arXiv:1211.4303},
  year   = {2014}
}

Comments

2 figures, 21 pages