English

Tetragonal intermediate modular curves

Number Theory 2024-07-23 v1

Abstract

For every group {±1}Δ(Z/NZ)×\{\pm1\}\subseteq \Delta\subseteq (\mathbb{Z}/N\mathbb{Z})^\times, there exists an intermediate modular curve XΔ(N)X_\Delta(N). In this paper we determine all curves XΔ(N)X_\Delta(N) whose Q\mathbb{Q}-gonality is equal to 44, all curves XΔ(N)X_\Delta(N) whose C\mathbb{C}-gonality is equal to 44, and all curves XΔ(N)X_\Delta(N) whose Q\mathbb{Q}-gonality is equal to 55. We also determine the Q\mathbb{Q}-gonality of all curves XΔ(N)X_\Delta(N) for N40N\leq 40 and {±1}Δ(Z/NZ)×\{\pm1\}\subsetneq \Delta \subsetneq (\mathbb{Z}/N\mathbb{Z})^\times.

Keywords

Cite

@article{arxiv.2407.14512,
  title  = {Tetragonal intermediate modular curves},
  author = {Petar Orlić},
  journal= {arXiv preprint arXiv:2407.14512},
  year   = {2024}
}