Geometry of PCF parameters in spaces of quadratic polynomials

Fuente: arXiv
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Main Authors: DeMarco, Laura, Mavraki, Niki Myrto
Format: Preprint
Published: 2023
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author DeMarco, Laura
Mavraki, Niki Myrto
author_facet DeMarco, Laura
Mavraki, Niki Myrto
contents We study algebraic relations among postcritically finite (PCF) parameters in the family $f_c(z) = z^2 + c$. Ghioca, Krieger, Nguyen and Ye proved that an algebraic curve in $\mathbb{C}^2$ contains infinitely many PCF pairs $(c_1, c_2)$ if and only if the curve is special (i.e., the curve is a vertical or horizontal line through a PCF parameter, or the curve is the diagonal). Here we extend this result to subvarieties of $\mathbb{C}^n$ for any $n\geq 2$. Consequently, we obtain uniform bounds on the number of PCF pairs on non-special curves in $\mathbb{C}^2$ and the number of PCF parameters in real algebraic curves in $\mathbb{C}$, depending only on the degree of the curve. We also compute the optimal bound for the general curve of degree $d$.
format Preprint
id arxiv_https___arxiv_org_abs_2310_05274
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Geometry of PCF parameters in spaces of quadratic polynomials
DeMarco, Laura
Mavraki, Niki Myrto
Dynamical Systems
Number Theory
We study algebraic relations among postcritically finite (PCF) parameters in the family $f_c(z) = z^2 + c$. Ghioca, Krieger, Nguyen and Ye proved that an algebraic curve in $\mathbb{C}^2$ contains infinitely many PCF pairs $(c_1, c_2)$ if and only if the curve is special (i.e., the curve is a vertical or horizontal line through a PCF parameter, or the curve is the diagonal). Here we extend this result to subvarieties of $\mathbb{C}^n$ for any $n\geq 2$. Consequently, we obtain uniform bounds on the number of PCF pairs on non-special curves in $\mathbb{C}^2$ and the number of PCF parameters in real algebraic curves in $\mathbb{C}$, depending only on the degree of the curve. We also compute the optimal bound for the general curve of degree $d$.
title Geometry of PCF parameters in spaces of quadratic polynomials
topic Dynamical Systems
Number Theory
url https://arxiv.org/abs/2310.05274