English

Galois subspaces for smooth projective curves

Algebraic Geometry 2020-12-23 v2

Abstract

Given an embedding of a smooth projective curve XX of genus g1g\geq1 into PN\mathbb{P}^N, we study the locus of linear subspaces of PN\mathbb{P}^N of codimension 2 such that projection from said subspace, composed with the embedding, gives a Galois morphism XP1X\to\mathbb{P}^1. For genus g2g\geq2 we prove that this locus is a smooth projective variety with components isomorphic to projective spaces. If g=1g=1 and the embedding is given by a complete linear system, we prove that this locus is also a smooth projective variety whose positive-dimensional components are isomorphic to projective bundles over \'etale quotients of the elliptic curve, and we describe these components explicitly.

Keywords

Cite

@article{arxiv.2005.13372,
  title  = {Galois subspaces for smooth projective curves},
  author = {Robert Auffarth and Sebastián Rahausen},
  journal= {arXiv preprint arXiv:2005.13372},
  year   = {2020}
}

Comments

To appear in Journal of Algebra. 17 pages including appendix. Comments are welcome!

R2 v1 2026-06-23T15:51:13.400Z