English

The Fundamental Group of a Compact Riemann Surface via Branched Covers

Algebraic Topology 2025-02-28 v2 Combinatorics

Abstract

Let XX be a compact Riemann surface of genus gg and let xXx \in X. We derive the classical presentation of π1(X,x)\pi_1(X,x) (i.e the one given by 2g2g generators a1,b1,,ag,bga_1,b_1, \dots, a_g,b_g and the relation i=1g[ai,bi]=1\prod_{i=1}^g[a_i,b_i] = 1) from the description of XX as a branched cover f:XCP1f : X \to \mathbb{C}\mathbb{P}^1.

Keywords

Cite

@article{arxiv.2501.18759,
  title  = {The Fundamental Group of a Compact Riemann Surface via Branched Covers},
  author = {Meirav Amram and Michael Chitayat and Yaacov Kopeliovich},
  journal= {arXiv preprint arXiv:2501.18759},
  year   = {2025}
}

Comments

Changed abstract. Added additional details throughout. Simplified notation where possible and corrected many minor issues