English

New unlikely intersections on elliptic surfaces

Algebraic Geometry 2025-08-12 v1

Abstract

Consider a Jacobian elliptic surface ECE \to C with a section PP of infinite order. Previous work of the first author and Urz\'ua over the complex numbers gives a bound on the number of tangencies between PP and a torsion section of EE (an ``unlikely intersection''), and more precisely, an exact formula for the weighted number of tangencies between PP and elements of the ``Betti foliation''. This work used analytic techniques that apparently do not generalize to positive characteristic. In this paper, we extend their work to characteristic pp, and we develop a second approach to tangency properties of algebraic curves on a complex elliptic surface, yielding a new family of unlikely intersections with a strong connection to a famous homomorphism of Manin. We also correct inaccuracies in the literature about this homomorphism.

Keywords

Cite

@article{arxiv.2508.06680,
  title  = {New unlikely intersections on elliptic surfaces},
  author = {Douglas Ulmer and José Felipe Voloch},
  journal= {arXiv preprint arXiv:2508.06680},
  year   = {2025}
}
R2 v1 2026-07-01T04:41:55.877Z