On the continuity of the solution map for polynomials

Fuente: arXiv
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Auteurs principaux: Parusiński, Adam, Rainer, Armin
Format: Preprint
Publié: 2024
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author Parusiński, Adam
Rainer, Armin
author_facet Parusiński, Adam
Rainer, Armin
contents In previous work, we proved that the continuous roots of a monic polynomial of degree $d$ whose coefficients depend in a $C^{d-1,1}$ way on real parameters belong to the Sobolev space $W^{1,q}$ for all $1\le q<d/(d-1)$. This is optimal. We obtained uniform bounds that show that the solution map ``coefficients-to-roots'' is bounded with respect to the $C^{d-1,1}$ and the Sobolev $W^{1,q}$ structures on source and target space, respectively. In this paper, we prove that the solution map is continuous, provided that we consider the $C^d$ structure on the space of coefficients. Since there is no canonical choice of an ordered $d$-tuple of the roots, we work in the space of $d$-valued Sobolev functions equipped with a strong notion of convergence. We also interpret the results in the Wasserstein space on the complex plane.
format Preprint
id arxiv_https___arxiv_org_abs_2410_01326
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the continuity of the solution map for polynomials
Parusiński, Adam
Rainer, Armin
Functional Analysis
Algebraic Geometry
Classical Analysis and ODEs
Differential Geometry
Metric Geometry
In previous work, we proved that the continuous roots of a monic polynomial of degree $d$ whose coefficients depend in a $C^{d-1,1}$ way on real parameters belong to the Sobolev space $W^{1,q}$ for all $1\le q<d/(d-1)$. This is optimal. We obtained uniform bounds that show that the solution map ``coefficients-to-roots'' is bounded with respect to the $C^{d-1,1}$ and the Sobolev $W^{1,q}$ structures on source and target space, respectively. In this paper, we prove that the solution map is continuous, provided that we consider the $C^d$ structure on the space of coefficients. Since there is no canonical choice of an ordered $d$-tuple of the roots, we work in the space of $d$-valued Sobolev functions equipped with a strong notion of convergence. We also interpret the results in the Wasserstein space on the complex plane.
title On the continuity of the solution map for polynomials
topic Functional Analysis
Algebraic Geometry
Classical Analysis and ODEs
Differential Geometry
Metric Geometry
url https://arxiv.org/abs/2410.01326