English

A dynamical Shafarevich theorem for rational maps over number fields and function fields

Algebraic Geometry 2017-05-17 v1

Abstract

We prove a dynamical Shafarevich theorem on the finiteness of the set of isomorphism classes of rational maps with fixed degeneracies. More precisely, fix an integer d at least 2 and let K be either a number field or the function field of a curve X over a field k, where k is of characteristic zero or p>2d-2 that is either algebraically closed or finite. Let S be a finite set of places of K. We prove the finiteness of the set of isomorphism classes of rational maps over K with a natural kind of good reduction outside of S. We also prove auxiliary results on finiteness of reduced effective divisors in PK1\mathbb{P}^1_K with good reduction outside of S and on the existence of global models for rational maps.

Keywords

Cite

@article{arxiv.1705.05489,
  title  = {A dynamical Shafarevich theorem for rational maps over number fields and function fields},
  author = {Lucien Szpiro and Lloyd West},
  journal= {arXiv preprint arXiv:1705.05489},
  year   = {2017}
}

Comments

16 pages

R2 v1 2026-06-22T19:47:59.139Z