English

Ekedahl-Oort types of $\mathbb{Z}/2\mathbb{Z}$-covers in characteristic $2$

Number Theory 2026-02-13 v2 Algebraic Geometry

Abstract

In this article we study the Ekedahl-Oort types of Z/2Z\mathbb{Z}/2\mathbb{Z}-Galois covers π:YX\pi:Y \to X in characteristic two. When the base curve XX is ordinary, we show that the Ekedahl-Oort type of YY is completely determined by the genus of XX and the ramification of π\pi. For a general base curve XX, we prove bounds on the Ekedahl-Oort depending on the Ekedahl-Oort type of XX and the ramification of π\pi. Along the way, we develop a theory of \emph{enhanced differentials of the second kind}. This theory allows us to study algebraic de Rham cohomology in any characteristic by working directly with differentials, in contrast to the standard \v{C}ech resolution.

Keywords

Cite

@article{arxiv.2511.02733,
  title  = {Ekedahl-Oort types of $\mathbb{Z}/2\mathbb{Z}$-covers in characteristic $2$},
  author = {Jeremy Booher and Steven R. Groen and Joe Kramer-Miller},
  journal= {arXiv preprint arXiv:2511.02733},
  year   = {2026}
}

Comments

40 pages, comments are welcome