English

On the fundamental group of a variety with quotient singularities

Algebraic Geometry 2013-11-26 v1

Abstract

Let k be a field, and let {\pi}:\tilde{X} -> X be a proper birational morphism of irreducible k-varieties, where \tilde{X} is smooth and X has at worst quotient singularities. When the characteristic of k is zero, a theorem of Koll\'ar in [Ko1] says that {\pi} induces an isomorphism of etale fundamental groups. We give a proof of this result which works for all characteristics. As an application, we prove that for a smooth projective irreducible surface X over an algebraically closed field k, the etale fundamental group of the Hilbert scheme of n points of X, where n > 1, is canonically isomorphic to the abelianization of the etale fundamental group of X. Koll\'ar has pointed out how the proof of the first result can be extended to cover the case of quotients by finite group schemes.

Keywords

Cite

@article{arxiv.1311.6086,
  title  = {On the fundamental group of a variety with quotient singularities},
  author = {Indranil Biswas and Amit Hogadi},
  journal= {arXiv preprint arXiv:1311.6086},
  year   = {2013}
}

Comments

20 pages. Final version to appear in IMRN