Polyhedral groups and pencils of K3-surfaces with maximal Picard number

Abstract

A K3-surface is a (smooth) surface which is simply connected and has trivial canonical bundle. In these notes we investigate three particular pencils of K3-surfaces with maximal Picard number. More precisely the general member in each pencil has Picard number 19 and each pencil contains four surfaces with Picard number 20. These surfaces are obtained as the minimal resolution of quotients X/G, where $G\subset SO(4,\R)$ is some finite subgroup and $X\subset \P_3(\C)$ denotes a G-invariant surface. The singularities of X/G come from fix points of G on X or from singularities of X. In any case the singularities on X/G are A-D-E surface singularities. The rational curves which resolve them and some extra 2-divisible sets, resp. 3-divisible sets of rational curves generate the Neron-Severi group of the minimal resolution.