Resumen de Mixed quasi-étale surfaces, new surfaces of general type with p_g=0 and their fundamental group

Davide Frapporti

• We call a projective surface ? mixed quasi-étale quotient if there exists a curve ? of genus ?(?)≥2 and a finite group ? that acts on ?×? exchanging the factors such that ?=(?×?)/? and the map ?×?→? has finite branch locus. The minimal resolution of its singularities is called mixed quasi-étale surface. We study the mixed quasi-étale surfaces under the assumption that (?×?)/?0 has only nodes as singularities, where ?0◃? is the index two subgroup of the elements that do not exchange the factors. We classify the minimal regular surfaces with ??=0 whose canonical model is a mixed quasi-étale quotient as above. All these surfaces are of general type and as an important byproduct, we provide an example of a numerical Campedelli surface with topological fundamental group ℤ4 , and we realize 2 new topological types of surfaces of general type. Three of the families we construct are ℚ -homology projective planes.