Simon Brandhorst

collaborators

5 papers

math.AG2020

Automorphism groups of certain Enriques surfaces

Simon Brandhorst, Ichiro Shimada

We calculate the automorphism group of certain Enriques surfaces. The Enriques surfaces that we investigate include very general $n$ -nodal Enriques surfaces and very general cuspid…

math.AG2019

Prime order isometries of unimodular lattices and automorphisms of ihs manifolds

Simon Brandhorst, Alberto Cattaneo

We characterize conjugacy classes of isometries of odd prime order in unimodular Z-lattices. This is applied to give a complete classification of odd prime order non-symplectic aut…

math.AG2019

Extensions of maximal symplectic actions on K3 surfaces

Simon Brandhorst, Kenji Hashimoto

We classify pairs $(X, G)$ consisting of a complex K3 surface $X$ and a finite group $G \leq A u t (X)$ such that the subgroup $G_{s} ⪇ G$ consisting of symplectic automorphisms is a…

math.AG2019

On characteristic polynomials of automorphisms of Enriques surfaces

Simon Brandhorst, Sławomir Rams, Ichiro Shimada

Let $f$ be an automorphism of a complex Enriques surface $Y$ and let $p_{f}$ denote the characteristic polynomial of the isometry $f^{*}$ of the numerical Néron-Severi lattice of $Y$ i…

math.AG2019

Borcherds' method for Enriques surfaces

Simon Brandhorst, Ichiro Shimada

We classify all primitive embeddings of the lattice of numerical equivalence classes of divisors of an Enriques surface with the intersection form multiplied by 2 into an even unim…