On the automorphism group of quotient modular curves

In this article, we determine the automorphism group of all the quotient modular curves of the modular curve X0(pq), where p, q are two distinct primes. In obtaining such results, we provide different insights to compute the automorphism group for any quotient modular curve, which are very effective...

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Detalles Bibliográficos
Autores: Bars Cortina, Francesc|||0000-0003-4779-3995, Dalal, Tarun|||0000-0003-4164-4737
Tipo de recurso: artículo
Fecha de publicación:2025
País:España
Institución:Universitat Autònoma de Barcelona
Repositorio:Dipòsit Digital de Documents de la UAB
Idioma:inglés
OAI Identifier:oai:ddd.uab.cat:309959
Acceso en línea:https://ddd.uab.cat/record/309959
https://dx.doi.org/urn:doi:10.1016/j.jalgebra.2025.02.037
Access Level:acceso embargado
Palabra clave:Automorphism group
Modular curve
Atkin-Lehner involution
Petri's theorem
Descripción
Sumario:In this article, we determine the automorphism group of all the quotient modular curves of the modular curve X0(pq), where p, q are two distinct primes. In obtaining such results, we provide different insights to compute the automorphism group for any quotient modular curve, which are very effective when the level of the curve is squarefree. In particular, in the case where the level of the quotient curve is non square-free, we would mention that we present an unfamiliar automorphism of order 3 for the genus 4 curve X∗0 (25 · 11) defined over Q[√5].