Abel's problem, Gauss and Cartier congruences over number fields

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Hauptverfasser: Delaygue, Éric, Rivoal, Tanguy
Format: Preprint
Veröffentlicht: 2025
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author Delaygue, Éric
Rivoal, Tanguy
author_facet Delaygue, Éric
Rivoal, Tanguy
contents Abel's problem consists in identifying the conditions under which the diferential equation $y'=ηy$, with $η$ an algebraic function in $\mathbb{C}(x)$, possesses a non-zero algebraic solution $y$. This problem has been algorithmically solved by Risch. In a previous paper, we have presented an alternative solution in the special arithmetic situation where $η$ has a Puiseux expansion with $\textit{rational}$ coefficients at the origin: there exists a non-trivial algebraic solution of $y'=ηy$ if and only if the coefficients of the Puiseux expansion of $xη(x)$ at $0$ satisfy Gauss congruences for almost all prime numbers. In this paper, we generalize this criterion to arbitrary $η$ algebraic over $\overline{\mathbb{Q}}(x)$, by means of a natural generalization to number fields of Gauss congruences and of the weaker Cartier congruences recently introduced in this context by Bostan. We then provide applications of this criterion in the hypergeometric setting and for Artin-Mazur zeta functions.
format Preprint
id arxiv_https___arxiv_org_abs_2501_16281
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Abel's problem, Gauss and Cartier congruences over number fields
Delaygue, Éric
Rivoal, Tanguy
Number Theory
Classical Analysis and ODEs
11A07, 33C20 (Primary) 34A05, 05A15 (Secondary)
Abel's problem consists in identifying the conditions under which the diferential equation $y'=ηy$, with $η$ an algebraic function in $\mathbb{C}(x)$, possesses a non-zero algebraic solution $y$. This problem has been algorithmically solved by Risch. In a previous paper, we have presented an alternative solution in the special arithmetic situation where $η$ has a Puiseux expansion with $\textit{rational}$ coefficients at the origin: there exists a non-trivial algebraic solution of $y'=ηy$ if and only if the coefficients of the Puiseux expansion of $xη(x)$ at $0$ satisfy Gauss congruences for almost all prime numbers. In this paper, we generalize this criterion to arbitrary $η$ algebraic over $\overline{\mathbb{Q}}(x)$, by means of a natural generalization to number fields of Gauss congruences and of the weaker Cartier congruences recently introduced in this context by Bostan. We then provide applications of this criterion in the hypergeometric setting and for Artin-Mazur zeta functions.
title Abel's problem, Gauss and Cartier congruences over number fields
topic Number Theory
Classical Analysis and ODEs
11A07, 33C20 (Primary) 34A05, 05A15 (Secondary)
url https://arxiv.org/abs/2501.16281