English

Remarks on a theorem of Silverman

Number Theory 2026-07-10 v1 Algebraic Geometry

Abstract

Motivated by a theorem of Silverman, we consider the following problem. Let AA be an abelian variety over a global field KK. Given a non-torsion point PA(K)P \in A(K), for a sufficiently large positive integer nn, whether there exists a place vv of KK such that the order of the reduction of PP modulo vv is nn? In this article, we first show that this holds for an elliptic curve over a global function field of positive characteristic p>3p>3 and for sufficiently large positive integers nn coprime to pp. In the second part of the paper, we consider its relative version over C\mathbb C. More precisely, let π:AS\pi: \mathcal{A} \rightarrow S be an abelian scheme over some variety SS over C\mathbb C, and let PP be a non-torsion section of π\pi. If the Betti map associated to PP is generically submersive, then for every sufficiently large nn, there is a point ss in S(C)S(\mathbb C) such that P(s)P(s) is a point of order nn in the corresponding fiber.

Keywords

Cite

@article{arxiv.2607.09002,
  title  = {Remarks on a theorem of Silverman},
  author = {Khai-Hoan Nguyen-Dang and Quang-Khai Nguyen},
  journal= {arXiv preprint arXiv:2607.09002},
  year   = {2026}
}