English

A generalization of the Oort Conjecture

Algebraic Geometry 2019-06-10 v3 Number Theory

Abstract

The Oort conjecture (now a theorem of Obus-Wewers and Pop) states that if k is an algebraically closed field of characteristic p, then any cyclic branched cover of smooth projective k-curves lifts to characteristic zero. This is equivalent to the local Oort conjecture, which states that all cyclic extensions of k[[t]] lift to characteristic zero. We generalize the local Oort conjecture to the case of Galois extensions with cyclic p-Sylow subgroups, reduce the conjecture to a pure characteristic p statement, and prove it in several cases. In particular, we show that D_9 is a so-called local Oort group.

Keywords

Cite

@article{arxiv.1502.07623,
  title  = {A generalization of the Oort Conjecture},
  author = {Andrew Obus},
  journal= {arXiv preprint arXiv:1502.07623},
  year   = {2019}
}

Comments

Final version, 60 pages. Only minor changes from previous version

R2 v1 2026-06-22T08:38:58.261Z