71 citations · 135 across the 24 of their papers we have counts for
26 papers
The two extremal rays of some Hyper-Kähler fourfolds
Federica Galluzzi, Bert Van Geemen
We consider projective Hyper-Kähler manifolds of dimension four that are deformation equivalent to Hilbert squares of K3 surfaces. In case such a manifold admits a divisorial contr…
Fourfolds of Weil type and the spinor map
Bert van Geemen
Recent papers by Markman and O'Grady give, besides their main results on the Hodge conjecture and on hyperkaehler varieties, surprising and explicit descriptions of families of abe…
Lagrangian Grassmannians and Spinor Varieties in Characteristic Two
Bert van Geemen, Alessio Marrani
The vector space of symmetric matrices of size has a natural map to a projective space of dimension given by the principal minors. This map extends to the Lagrangian Gr…
Genus three curves and 56 nodal sextic surfaces
Bert van Geemen, Yan Zhao
Catanese and Tonoli showed that the maximal cardinality for an even set of nodes on a sextic surface is 56 and they constructed such nodal surfaces. In this paper we give an altern…
On intermediate Jacobians of cubic threefolds admitting an automorphism of order five
Bert van Geemen, Takuya Yamauchi
Let be a field of characteristic zero containing a primitive fifth root of unity. Let be a smooth cubic threefold with an automorphism of order five, then we observe that…
The Cayley-Oguiso automorphism of positive entropy on a K3 surface
Dino Festi, Alice Garbagnati, Bert van Geemen +1
Recently Oguiso showed the existence of K3 surfaces that admit a fixed point free automorphism of positive entropy. The K3 surfaces used by Oguiso have a particular rank two Picard…