English

Iwasawa Dieudonn\'e theory of function fields

Number Theory 2022-09-07 v2 Algebraic Geometry

Abstract

Let kk be a perfect field of characteristic pp and Γ\Gamma an infinite, first countable pro-pp group. We study the behavior of the pp-primary part of the "motivic class group", i.e. the full pp-divisible group of the Jacobian, in any Γ\Gamma-tower of function fields over kk that is unramified outside a finite (possibly empty) set of places Σ\Sigma, and totally ramified at every place of Σ\Sigma. When Σ=\Sigma=\emptyset and Γ\Gamma is a torsion free pp-adic Lie group, we obtain asymptotic formulae which show that the pp-torsion class group schemes grow in a remarkably regular manner. In the ramified setting Σ\Sigma\neq\emptyset, we obtain a similar asymptotic formula for the pp-torsion in "physical class groups", i.e. the kk-rational points of the Jacobian, which generalizes the work of Mazur and Wiles, who studied the case Γ=Zp\Gamma=\mathbf{Z}_p.

Keywords

Cite

@article{arxiv.2207.02283,
  title  = {Iwasawa Dieudonn\'e theory of function fields},
  author = {Bryden Cais},
  journal= {arXiv preprint arXiv:2207.02283},
  year   = {2022}
}

Comments

Corollaries 1.4 and 1.5 slightly weakened due to potential mistake in key reference in proof of these results in v1. Remark 3.11 (most of which appeared as a footnote in v1) added, and Remark 3.16 adjusted. Introduction modified to to reflect these changes, and a few typos corrected

R2 v1 2026-06-24T12:15:02.776Z