Primitive divisors of sequences associated to elliptic curves over function fields
Abstract
We study the existence of a Zsigmondy bound for a sequence of divisors associated to points on an elliptic curve over a function field. More precisely, let be an algebraically closed field, let be a nonsingular projective curve over , and let denote the function field of . Suppose is an ordinary elliptic curve over and suppose there does not exist an elliptic curve defined over that is isomorphic to over . Suppose is a non-torsion point and is a torsion point of order . The sequence of points induces a sequence of effective divisors on . We provide conditions on and the characteristic of for there to exist a bound such that has a primitive divisor for all . This extends the analogous result of Verzobio in the case where is a number field.
Keywords
Cite
@article{arxiv.2103.06787,
title = {Primitive divisors of sequences associated to elliptic curves over function fields},
author = {Robert Slob},
journal= {arXiv preprint arXiv:2103.06787},
year = {2021}
}
Comments
13 pages. New version: in the old version, we assumed in Theorem 1 that the torsion point $Q$ had prime order unequal to the characteristic of $k$. It was pointed out by a colleague that some small adaptations allow us to extend the main theorem to where $Q$ is a torsion point of arbitrary order (as long as the characteristic of $k$ and the order of $Q$ are not too small, see Table 1)