English

Chabauty without the Mordell-Weil group

Number Theory 2019-08-20 v2

Abstract

Based on ideas from recent joint work with Bjorn Poonen, we describe an algorithm that can in certain cases determine the set of rational points on a curve CC, given only the pp-Selmer group SS of its Jacobian (or some other abelian variety CC maps to) and the image of the pp-Selmer set of CC in SS. The method is more likely to succeed when the genus is large, which is when it is usually rather difficult to obtain generators of a finite-index subgroup of the Mordell-Weil group, which one would need to apply Chabauty's method in the usual way. We give some applications, for example to generalized Fermat equations of the form x5+y5=zpx^5 + y^5 = z^p.

Cite

@article{arxiv.1506.04286,
  title  = {Chabauty without the Mordell-Weil group},
  author = {Michael Stoll},
  journal= {arXiv preprint arXiv:1506.04286},
  year   = {2019}
}

Comments

35 pages. v2: improved exposition in Section 2, promoted Propositions 2.1 and 2.6 to theorems; moved old Section 4 (now Section 3) before old Section 3 (now 4) and changed the new Section 3 to cover the general case (arbitrary $k$ and $p$ instead of $\mathbb Q$ and 2); improved the sufficient criterion for FLT in Section 7; minor edits throughout

R2 v1 2026-06-22T09:53:07.937Z