4 papers
On K3 surfaces with hyperbolic automorphism groups
Koji Fujiwara, Keiji Oguiso, Xun Yu
We show the finiteness of the Néron-Severi lattices of complex projective K3 surfaces whose automorphism groups are non-elementary hyperbolic with explicit descriptions, under the…
On the number of real forms of a complex variety
Gerard van der Geer, Xun Yu
We give a bound on the number of weighted real forms of a complex variety with finite automorphism group, where the weight is the inverse of the number of automorphisms of the real…
Nonrational varieties with unirational parametrizations of coprime degrees
Song Yang, Xun Yu, Zigang Zhu
We show that there exists a -dimensional family of smooth cubic threefolds admitting unirational parametrizations of coprime degrees. This together with Clemens--Griffiths' work…
On automorphism groups of smooth hypersurfaces
Song Yang, Xun Yu, Zigang Zhu
We show that smooth hypersurfaces in complex projective spaces with automorphism groups of maximum size are isomorphic to Fermat hypersurfaces, with a few exceptions. For the excep…