English

On rational functions with more than three branch points

Geometric Topology 2020-05-15 v3 Algebraic Geometry Group Theory

Abstract

Let Λ\Lambda be a collection of partitions of a positive integer dd of the form (a1,,ap),(b1,,bq),(m1+1,1,,1),,(ml+1,1,,1),(a_1,\cdots, a_p),\,(b_1,\cdots, b_q),\,(m_1+1,1,\cdots,1),\cdots, (m_l+1,1,\cdots,1), where (m1,,ml)(m_1,\cdots, m_l) is a partition of p+q2>0p+q-2>0. We prove that there exists a rational function on the Riemann sphere C\overline{\mathbb{C}} with branch data Λ\Lambda if and only if max(m1,,ml)<dGCD(a1,,ap,b1,,bq).\max\bigl(m_1,\cdots,m_l\bigr) < \frac{d}{{\rm GCD}(a_1,\cdots, a_p,b_1,\cdots, b_q)}. As an application, we give a new class of branch data which can be realized by Belyi functions on the Riemann sphere.

Keywords

Cite

@article{arxiv.1510.06291,
  title  = {On rational functions with more than three branch points},
  author = {Jijian Song and Bin Xu},
  journal= {arXiv preprint arXiv:1510.06291},
  year   = {2020}
}

Comments

19 pages We change the title. We improve exposition the manuscript greatly. Any comments are welcome!

R2 v1 2026-06-22T11:25:41.283Z