English

Chabauty--Kim, finite descent, and the Section Conjecture for locally geometric sections

Number Theory 2026-04-14 v2 Algebraic Geometry

Abstract

Let XX be a smooth projective curve of genus 2\geq2 over a number field. A natural variant of Grothendieck's Section Conjecture postulates that every section of the fundamental exact sequence for XX which everywhere locally comes from a point of XX in fact globally comes from a point of XX. We show that X/QX/\mathbb{Q} satisfies this version of the Section Conjecture if it satisfies Kim's Conjecture for almost all choices of auxiliary prime pp, and give the appropriate generalisation to SS-integral points on hyperbolic curves. This gives a new "computational" strategy for proving instances of this variant of the Section Conjecture, which we carry out for the thrice-punctured line over Z[1/2]\mathbb{Z}[1/2].

Keywords

Cite

@article{arxiv.2305.09462,
  title  = {Chabauty--Kim, finite descent, and the Section Conjecture for locally geometric sections},
  author = {L. Alexander Betts and Theresa Kumpitsch and Martin Lüdtke},
  journal= {arXiv preprint arXiv:2305.09462},
  year   = {2026}
}

Comments

51 pages; minor revision; appendix rewritten, 'finite descent' added to the title