Intersecting the torsion of elliptic curves

Fuente: arXiv
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Main Authors: Garcia-Fritz, Natalia, Pasten, Hector
Format: Preprint
Published: 2023
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author Garcia-Fritz, Natalia
Pasten, Hector
author_facet Garcia-Fritz, Natalia
Pasten, Hector
contents In 2007, Bogomolov and Tschinkel proved that given two complex elliptic curves $E_1$ and $E_2$ along with even degree-$2$ maps $π_j\colon E_j\to \mathbb{P}^1$ having different branch loci, the intersection of the image of the torsion points of $E_1$ and $E_2$ under their respective $π_j$ is finite. They conjectured (also in works with Fu) that the cardinality of this intersection is uniformly bounded independently of the elliptic curves. As it has been observed in the literature, the recent proof of the Uniform Manin-Mumford conjecture implies a full solution of the Bogomolov-Fu-Tschinkel conjecture. In this work we prove a generalization of the Bogomolov-Fu-Tschinkel conjecture where instead of even degree-$2$ maps one can use any rational functions of bounded degree on the elliptic curves as long as they have different branch loci. Our approach combines Nevanlinna theory with the Uniform Manin-Mumford conjecture. With similar techniques, we also prove a result on lower bounds for ranks of elliptic curves over number fields.
format Preprint
id arxiv_https___arxiv_org_abs_2308_05708
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Intersecting the torsion of elliptic curves
Garcia-Fritz, Natalia
Pasten, Hector
Number Theory
Primary: 11G05, Secondary: 14G25, 14H52
In 2007, Bogomolov and Tschinkel proved that given two complex elliptic curves $E_1$ and $E_2$ along with even degree-$2$ maps $π_j\colon E_j\to \mathbb{P}^1$ having different branch loci, the intersection of the image of the torsion points of $E_1$ and $E_2$ under their respective $π_j$ is finite. They conjectured (also in works with Fu) that the cardinality of this intersection is uniformly bounded independently of the elliptic curves. As it has been observed in the literature, the recent proof of the Uniform Manin-Mumford conjecture implies a full solution of the Bogomolov-Fu-Tschinkel conjecture. In this work we prove a generalization of the Bogomolov-Fu-Tschinkel conjecture where instead of even degree-$2$ maps one can use any rational functions of bounded degree on the elliptic curves as long as they have different branch loci. Our approach combines Nevanlinna theory with the Uniform Manin-Mumford conjecture. With similar techniques, we also prove a result on lower bounds for ranks of elliptic curves over number fields.
title Intersecting the torsion of elliptic curves
topic Number Theory
Primary: 11G05, Secondary: 14G25, 14H52
url https://arxiv.org/abs/2308.05708