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arXiv · 2504.18894

Maximal curves over finite fields and a modular isogeny

Valerio Dose·Guido Lido·Pietro Mercuri·Claudio Stirpe
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Abstract

We prove the existence of curves of genus $7$ and $12$ over the field with $11^5$ elements, reaching the Hasse-Weil-Serre upper bound. These curves are quotients of modular curves and we give explicit equations. We compute the number of points of many quotient modular curves in the same family without providing equations. For various pairs (genus, finite field) we find new records for the largest known number of points. In other instances we find quotient modular curves that are maximal, matching already known results. To perform these computations, we provide a generalization of Chen's isogeny result.

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Valerio Dose, Guido Lido, Pietro Mercuri, Claudio Stirpe. 2025-04-26. Maximal curves over finite fields and a modular isogeny. https://arxiv.org/abs/2504.18894

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