English

On the existence of ramified abelian covers

Algebraic Geometry 2023-10-10 v3

Abstract

Given a normal complete variety YY over an algebraically closed field K\mathbb K, distinct effective Weil divisors D1,...DnD_1,... D_n of YY and positive integers d1,...dnd_1,... d_n, we spell out the conditions for the existence of an abelian cover of YY branched with order did_i on DiD_i. As an application, we prove that a cover of a normal complete toric variety branched on the torus-invariant divisors is itself a toric variety if the characteristic of K\mathbb K is equal to 0 or if the cover is Galois of degree not divisible by the characteristic.

Keywords

Cite

@article{arxiv.1210.6174,
  title  = {On the existence of ramified abelian covers},
  author = {Valery Alexeev and Rita Pardini},
  journal= {arXiv preprint arXiv:1210.6174},
  year   = {2023}
}

Comments

Dedicated to Alberto Conte on his 70th birthday. Version 3: Thm. 3.7 has been reformulated. We thank Boaz Moerman for pointing out that the earlier version of this result was incorrect