English

On the algebraic fundamental group of surfaces with K^2\leq 3\chi

Algebraic Geometry 2007-05-23 v3

Abstract

Let S be a minimal complex surface of general type with q(S)=0q(S)=0. We prove the following statements concerning the algebraic fundamental group: I) Assume that K^2_S\leq 3\chi(S). Then S has an irregular etale cover if and only if S has a free pencil of hyperelliptic curves of genus 3 with at least 4 double fibres. II) If K^2_S=3 and \chi(S)=1, then S has no irregular etale cover. III) If K^2_S<3\chi(S) and S does not have any irregular etale cover, then the order of the algebraic fundamental group is lesser or equal to 9, and if equality occurs then K^2_S=2, \chi(S)=1.

Keywords

Cite

@article{arxiv.math/0512483,
  title  = {On the algebraic fundamental group of surfaces with K^2\leq 3\chi},
  author = {Margarida Mendes Lopes and Rita Pardini},
  journal= {arXiv preprint arXiv:math/0512483},
  year   = {2007}
}

Comments

Final version, to appear in J.D.G