English

Counting rational maps on $\mathbb{P}^1$ with prescribed local conditions

Number Theory 2026-01-30 v3 Dynamical Systems

Abstract

We explore distribution questions for rational maps on the projective line P1\mathbb{P}^1 over Q\mathbb{Q} within the framework of arithmetic dynamics, drawing analogies to elliptic curves. Specifically, we investigate counting problems for rational maps ϕ\phi of fixed degree d2d \geq 2 with prescribed reduction properties. Our main result establishes that the set of rational maps with minimal resultant has positive density. Additionally, for degree 2 rational maps, we perform explicit computations demonstrating that over 32.7%32.7\% possess a squarefree, and hence minimal, resultant.

Keywords

Cite

@article{arxiv.2408.15648,
  title  = {Counting rational maps on $\mathbb{P}^1$ with prescribed local conditions},
  author = {Khoa D. Nguyen and Anwesh Ray},
  journal= {arXiv preprint arXiv:2408.15648},
  year   = {2026}
}

Comments

Version 3: 29 pages, accepted for publication in Research in Number theory

R2 v1 2026-06-28T18:26:21.149Z