Bounds on Heights of $2$-isogeny Graphs in Ordinary Curves over $\mathbb{F}_p$ and $\mathbb{F}_{p^2}$ and Its Application

Fuente: arXiv
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Autores principales: Hashimoto, Yuji, Nuida, Koji
Formato: Preprint
Publicado: 2024
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author Hashimoto, Yuji
Nuida, Koji
author_facet Hashimoto, Yuji
Nuida, Koji
contents It is known that any isogeny graph consisting of ordinary elliptic curves over $\mathbb{F}_q$ with $q = p$ or $p^2$ has a special structure, called a volcano graph. We have a bound $h < \log_2 \sqrt{4q}$ of a height $h$ of the $2$-volcano graph. In this paper, we improve the bound on a height of $2$-volcano graphs over $\mathbb{F}_q$. In case $q = p^2$, we show a tighter bound $h \leq \left\lfloor \frac{ 1 }{ 2 } \lfloor \log_2 p \rfloor \right\rfloor + 2 $. In case $q = p$, we also show that a good bound for each prime $p$ can be computed by using our proposed techniques.
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id arxiv_https___arxiv_org_abs_2409_00505
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Bounds on Heights of $2$-isogeny Graphs in Ordinary Curves over $\mathbb{F}_p$ and $\mathbb{F}_{p^2}$ and Its Application
Hashimoto, Yuji
Nuida, Koji
Number Theory
It is known that any isogeny graph consisting of ordinary elliptic curves over $\mathbb{F}_q$ with $q = p$ or $p^2$ has a special structure, called a volcano graph. We have a bound $h < \log_2 \sqrt{4q}$ of a height $h$ of the $2$-volcano graph. In this paper, we improve the bound on a height of $2$-volcano graphs over $\mathbb{F}_q$. In case $q = p^2$, we show a tighter bound $h \leq \left\lfloor \frac{ 1 }{ 2 } \lfloor \log_2 p \rfloor \right\rfloor + 2 $. In case $q = p$, we also show that a good bound for each prime $p$ can be computed by using our proposed techniques.
title Bounds on Heights of $2$-isogeny Graphs in Ordinary Curves over $\mathbb{F}_p$ and $\mathbb{F}_{p^2}$ and Its Application
topic Number Theory
url https://arxiv.org/abs/2409.00505