Listing superspecial curves of genus three using Richelot isogeny graphs

Fuente: arXiv
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Main Authors: Ohashi, Ryo, Onuki, Hiroshi, Kudo, Momonari, Yoshizumi, Ryo, Nuida, Koji
Format: Preprint
Published: 2024
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_version_ 1866913942898475008
author Ohashi, Ryo
Onuki, Hiroshi
Kudo, Momonari
Yoshizumi, Ryo
Nuida, Koji
author_facet Ohashi, Ryo
Onuki, Hiroshi
Kudo, Momonari
Yoshizumi, Ryo
Nuida, Koji
contents In algebraic geometry, superspecial curves are important research objects. While the number of superspecial genus-3 curves in characteristic $p$ is known, the number of hyperelliptic ones among them has not been determined even for small $p$. In this paper, in order to compute the latter number, we give an explicit algorithm for computing the Richelot isogeny graph of superspecial principally polarized abelian varieties of dimension 3 using theta functions. In particular, one can determine whether a given vertex in the graph corresponds to the Jacobian of a genus-3 curve or not, and restore the defining equation of such a genus-3 curve from its theta constants. Our algorithm enables efficient enumeration of superspecial genus-3 curves, as all operations can be performed in $\mathbb{F}_{p^2}$. By implementing the algorithm in Magma, we successfully counted the number of hyperelliptic curves among them for all primes $11 \leq p < 100$.
format Preprint
id arxiv_https___arxiv_org_abs_2401_10500
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Listing superspecial curves of genus three using Richelot isogeny graphs
Ohashi, Ryo
Onuki, Hiroshi
Kudo, Momonari
Yoshizumi, Ryo
Nuida, Koji
Algebraic Geometry
14K02, 14K25 (Primary) 14H45, 14Q05 (Secondary)
In algebraic geometry, superspecial curves are important research objects. While the number of superspecial genus-3 curves in characteristic $p$ is known, the number of hyperelliptic ones among them has not been determined even for small $p$. In this paper, in order to compute the latter number, we give an explicit algorithm for computing the Richelot isogeny graph of superspecial principally polarized abelian varieties of dimension 3 using theta functions. In particular, one can determine whether a given vertex in the graph corresponds to the Jacobian of a genus-3 curve or not, and restore the defining equation of such a genus-3 curve from its theta constants. Our algorithm enables efficient enumeration of superspecial genus-3 curves, as all operations can be performed in $\mathbb{F}_{p^2}$. By implementing the algorithm in Magma, we successfully counted the number of hyperelliptic curves among them for all primes $11 \leq p < 100$.
title Listing superspecial curves of genus three using Richelot isogeny graphs
topic Algebraic Geometry
14K02, 14K25 (Primary) 14H45, 14Q05 (Secondary)
url https://arxiv.org/abs/2401.10500