JongHae Keum

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First, we formulate and prove Theorem of Lie-Kolchin type for a cone and derive some algebro-geometric consequences. Next, inspired by a recent result of Dinh and Sibony we pose a conjecture of Tits type for a group of automorphisms of a complex variety and verify its weaker version. Finally, applying Theorem of Lie-Kolchin type for a cone, we confirm the(More)
In this paper we study automorphisms g of order p of K3-surfaces defined over an algebraically closed field of characteristic p > 0. We divide all possible actions in the following cases according to the structure of the set of fixed points X g : X g is a finite set, X g contains a one-dimensional part D which is a positive divisor of Kodaira dimension κ(X,(More)
We find generators of the group of birational automorphisms of the Hessian surface of a general cubic surface. Its nonsingular minimal model is a K3 surface with the Picard lattice of rank 16 which embeds naturally in the even unimodular lattice II 1,25 of rank 26 and signature (1, 25). The generators are related to reflections with respect to some Leech(More)
A normal projective complex surface is called a rational homology projective plane if it has the same Betti numbers with the complex projective plane CP 2. It is known that a rational homology projective plane with quotient singularities has at most 5 singular points. But all known examples have at most 4 singular points. In this paper, we prove that a(More)