On intersection of lemniscates of rational functions

Fuente: arXiv
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Autores principales: Orevkov, Stepan, Pakovich, Fedor
Formato: Preprint
Publicado: 2023
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author Orevkov, Stepan
Pakovich, Fedor
author_facet Orevkov, Stepan
Pakovich, Fedor
contents For a non-constant complex rational function $P$, the lemniscate of $P$ is defined as the set of points $z\in \mathbb C$ such that $\vert P(z)\vert =1$. The lemniscate of $P$ coincides with the set of real points of the algebraic curve given by the equation $L_P(x,y)=0$, where $L_P(x,y)$ is the numerator of the rational function $P(x+iy)\overline{ P}(x-iy)-1.$ In this paper, we study the following two questions: under what conditions two lemniscates have a common component, and under what conditions the algebraic curve $L_P(x,y)=0$ is irreducible. In particular, we provide a sharp bound for the number of complex solutions of the system $\vert P_1(z)\vert =\vert P_2(z)\vert =1$, where $P_1$ and $P_2$ are rational functions.
format Preprint
id arxiv_https___arxiv_org_abs_2309_04983
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On intersection of lemniscates of rational functions
Orevkov, Stepan
Pakovich, Fedor
Algebraic Geometry
Complex Variables
Number Theory
For a non-constant complex rational function $P$, the lemniscate of $P$ is defined as the set of points $z\in \mathbb C$ such that $\vert P(z)\vert =1$. The lemniscate of $P$ coincides with the set of real points of the algebraic curve given by the equation $L_P(x,y)=0$, where $L_P(x,y)$ is the numerator of the rational function $P(x+iy)\overline{ P}(x-iy)-1.$ In this paper, we study the following two questions: under what conditions two lemniscates have a common component, and under what conditions the algebraic curve $L_P(x,y)=0$ is irreducible. In particular, we provide a sharp bound for the number of complex solutions of the system $\vert P_1(z)\vert =\vert P_2(z)\vert =1$, where $P_1$ and $P_2$ are rational functions.
title On intersection of lemniscates of rational functions
topic Algebraic Geometry
Complex Variables
Number Theory
url https://arxiv.org/abs/2309.04983