On the existence of a morphism between certain Artin-Schreier curves

Fuente: arXiv
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Main Authors: Lucas, Beatriz Barbero, Lia, Stefano, McGuire, Gary
Format: Preprint
Published: 2026
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author Lucas, Beatriz Barbero
Lia, Stefano
McGuire, Gary
author_facet Lucas, Beatriz Barbero
Lia, Stefano
McGuire, Gary
contents It is well known that, given two curves $\mathcal{X}: y^p+cy=x^m$ and $\mathcal{Y}:y^p+cy=x^n$, defined over $\F_p$, if $n$ divides $m$ then there exists a nonconstant morphism $\mathcal{X} \longrightarrow \mathcal{Y}$. In this paper we are interested in studying whether the converse of this statement is true, i.e., if there exists a morphism $\mathcal{X} \longrightarrow\mathcal{Y}$ then must it be true that $n$ divides $m$? In particular, we consider the case when $m=p^{k}+1$ and $n=p^\ell+1$. We prove that the converse is true under certain hypotheses. We deal with both the cases of Galois morphisms and non-Galois morphisms.
format Preprint
id arxiv_https___arxiv_org_abs_2602_15717
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the existence of a morphism between certain Artin-Schreier curves
Lucas, Beatriz Barbero
Lia, Stefano
McGuire, Gary
Algebraic Geometry
11G20 (Primary), 14H30, 14H37 (Secondary)
It is well known that, given two curves $\mathcal{X}: y^p+cy=x^m$ and $\mathcal{Y}:y^p+cy=x^n$, defined over $\F_p$, if $n$ divides $m$ then there exists a nonconstant morphism $\mathcal{X} \longrightarrow \mathcal{Y}$. In this paper we are interested in studying whether the converse of this statement is true, i.e., if there exists a morphism $\mathcal{X} \longrightarrow\mathcal{Y}$ then must it be true that $n$ divides $m$? In particular, we consider the case when $m=p^{k}+1$ and $n=p^\ell+1$. We prove that the converse is true under certain hypotheses. We deal with both the cases of Galois morphisms and non-Galois morphisms.
title On the existence of a morphism between certain Artin-Schreier curves
topic Algebraic Geometry
11G20 (Primary), 14H30, 14H37 (Secondary)
url https://arxiv.org/abs/2602.15717