Extensions of maximal symplectic actions on K3 surfaces

Abstract

We classify pairs $(X,G)$ consisting of a complex K3 surface $X$ and a finite group $G\le Aut(X)$ such that the subgroup $G_s⪇G$ consisting of symplectic automorphisms is among the $11$ maximal symplectic ones as classified by Mukai.

See the ancillary files for matrices representing the 42 actions. v3: Improved presentation