Reconstruction theorem for complex polynomials

TL;DR

This paper extends Takens' Reconstruction Theorem to complex polynomials, showing that ergodic properties are preserved for most cases, and provides a reconstruction result for polynomial iteration using real projections.

Contribution

It generalizes previous results to include exceptional polynomials and establishes a reconstruction theorem for complex polynomial iteration via real projections.

Findings

Ergodic properties extend to exceptional polynomials unless Julia set is in an invariant line.

Reconstruction map can recover the 2m+1-st image of the polynomial iteration.

Main theorem applies to generic complex polynomials with real projections.

Abstract

Recently Takens' Reconstruction Theorem was studied in the complex analytic setting by Forn{\ae}ss and Peters \cite{FP}. They studied the real orbits of complex polynomials, and proved that for non-exceptional polynomials ergodic properties such as measure theoretic entropy are carried over to the real orbits mapping. Here we show that the result from \cite{FP} also holds for exceptional polynomials, unless the Julia set is entirely contained in an invariant vertical line, in which case the entropy is $0$. In \cite{T2} Takens proved a reconstruction theorem for endomorphisms. In this case the reconstruction map is not necessarily an embedding, but the information of the reconstruction map is sufficient to recover the $2m+1$-st image of the original map. Our main result shows an analogous statement for the iteration of generic complex polynomials and the projection onto the real axis.