K3 surfaces with order 11 automorphisms

Automorphism groups of certain Enriques surfaces

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 cuspidal Enriques surfaces. We also describe the action of the automorphism group on the set of smooth rational curves and on the set of elliptic fibrations.

Order 9 automorphisms of K3 surfaces

In this paper we provide a complete classification of non-symplectic automorphisms of order nine of complex K3 surfaces.

A surface birational to an Enriques surface with non-finitely generated automorphism group

We will show that there is a smooth complex projective surface, birational to some Enriques surface, such that the automorphism group is discrete but not finitely generated.

Coble surfaces with finite automorphism group

We classify Coble surfaces with finite automorphism group in arbitrary characteristic not equal to 2. There are exactly 9 isomorphism classes of such surfaces.

Automorphisms of A1-fibered surfaces

We develop technics of birational geometry to study automorphisms of affine surfaces admitting many distinct rational fibrations, with a particular focus on the interactions between automorphisms and these fibrations. In particular, we associate to each surface $S$ of this type a graph encoding equivalence classes of rational fibrations from which it is possible to decide for instance if the automorphism group of $S$ is generated by automorphisms preserving these fibrations.

On the characterization of Danielewski surfaces by their automorphism group

In this note we show that if the automorphism group of a normal affine surface $S$ is isomorphic to the automorphism group of a Danielewski surface, then $S$ is isomorphic to a Danielewski surface.

The automorphism groups of certain singular K3 surfaces and an Enriques surface

We present finite sets of generators of the full automorphism groups of three singular K3 surfaces, on which the alternating group of degree 6 acts symplectically. We also present a finite set of generators of the full automorphism group of an associated Enriques surface, on which the Mathieu group M_{10} acts.

Riemann surfaces with a large abelian group of automorphisms

In this paper we classify all Riemann surfaces having a large abelian group of automorphisms, that is having an abelian group of automorphism of order strictly bigger then $4(g-1)$, where $g$ denotes as usual the genus of the Riemann surface.

K3 surface entropy and automorphism groups

We derive a characterization of the complex projective K3 surfaces which have automorphisms of positive entropy in term of their Néron-Severi lattices. Along the way, we classify the projective K3 surfaces of zero entropy with infinite automorphism groups and we determine the projective K3 surfaces of Picard number at least five with almost abelian automorphism groups, which gives an answer to a long standing question of Nikulin.

K3 surfaces with an automorphism of order 11

This paper concerns K3 surfaces with automorphisms of order 11 in arbitrary characteristic. Specifically we study the wild case and prove that a general such surface in characteristic 11 has Picard number 2. We also construct K3 surfaces with an automorphism of order 11 in every characteristic, and supersingular K3 surfaces whenever possible.

Automorphismes naturels de l'espace de Douady de points sur une surface

We prove some general results concerning the size of the group of automorphisms of the Douady space of points on a surface. We then study some properties of the automorphisms coming from an automorphism of the surface, in particular their action on the cohomology and the classification of their fixed points.

Automorphism groups of Inoue and Kodaira surfaces

We prove that automorphism groups of Inoue and primary Kodaira surfaces are Jordan.

Minimum positive entropy of complex Enriques surface automorphisms

We determine the minimum positive entropy of complex Enriques surface automorphisms. This together with McMullen's work completes the determination of the minimum positive entropy of complex surface automorphisms in each class of Enriques-Kodaira classification of complex surfaces.

Automorphisms of cubic surfaces without points

We classify finite groups acting by birational transformations of a non-trivial Severi--Brauer surface over a field of characteristc zero that are not conjugate to subgroups of the automorphism group. Also, we show that the automorphism group of a smooth cubic surface over a field $K$ of characteristic zero that has no $K$-points is abelian, and find a sharp bound for the Jordan constants of birational automorphism groups of such cubic surfaces.

Automorphisms of quasi-projective surfaces over fields of finite characteristic

We prove that the group of automorphisms of any quasi-projective surface $S$ in finite characteristic has the $p$-Jordan property.

Cyclic groups of automorphisms of complex K3 surfaces

We determine all possible orders of automorphisms of complex K3 surfaces. A positive integer N is the order of an automorphism of a complex K3 surface if and only if $ϕ(N) \leq 20$ where $ϕ$ is the Euler function.

具有外伽罗瓦点的四次曲面与具有4阶自同构的K3曲面

Quartic surfaces with an outer Galois point and K3 surfaces with an automorphism of order 4

本文建立了具有外伽罗瓦点的光滑四次曲面与具有特定4阶自同构的K3曲面之间的一一对应，并进一步用K3曲面刻画了具有两个及以上外伽罗瓦点的四次曲面。

奇特征下del Pezzo曲面的自同构

Automorphisms of del Pezzo surfaces in odd characteristic

本文在奇正特征的代数闭域上，完成了del Pezzo曲面自同构群的分类工作。

Classification of non-symplectic automorphisms on K3 surfaces which act trivially on the Néron-Severi lattice

We treat non-symplectic automorphisms on $K3$ surfaces which act trivially on the Néron-Severi lattice. In this paper, we classify non-symplectic automorphisms of prime-power order, especially 2-power order on $K3$ surfaces, i.e., we describe their fixed locus.

Automorphism groups in a family of K3 surfaces

A few facts concerning the phrase "the automorphism groups become larger at special points of the moduli of K3 surfaces" are presented. It is also shown that the automorphism groups are of infinite order over a dense subset in any one-dimensional non-trivial family of projective K3 surfaces.

On Enriques surfaces in characteristic 2 with a finite group of automorphisms

Complex Enriques surfaces with a finite group of automorphisms are classified into seven types. In this paper, we determine which types of such Enriques surfaces exist in characteristic 2. In particular we give a one dimensional family of classical and supersingular Enriques surfaces with the automorphism group isomorphic to the symmetric group of degree five.

On automorphisms and the cone conjecture for Enriques surfaces in odd characteristic

We prove that, for an Enriques surface in odd characteristic, the automorphism group is finitely generated and it acts on the effective nef cone with a rational polyhedral fundamental domain. We also construct a smooth projective surface in odd characteristic which is birational to an Enriques surface and whose automorphism group is discrete but not finitely generated.

Automorphism groups of rational elliptic and quasi-elliptic surfaces in all characteristics

We study the groups of automorphisms of rational algebraic surfaces that admit a relatively minimal pencil of curves of arithmetic genus one over an algebraically closed field of arbitrary characteristic. In particular, we classify such surfaces that admit non-trivial automorphisms that act trivially on the Picard group. As an application, we classify classical Enriques surfaces in characteristic $2$ that admit non-trivial numerically trivial automorphisms.

On automorphisms group of some K3 surfaces

In this paper we study the automorphisms group of some K3 surfaces which are double covers of the projective plane ramified over a smooth sextic plane curve. More precisely, we study some particlar case of a K3 surface of Picard rank two.

Classification of Enriques surfaces with finite automorphism group in characteristic 2

We classify supersingular and classical Enriques surfaces with finite automorphism group in characteristic 2 into 8 types according to their dual graphs of all $(-2)$-curves (nonsigular rational curves). We give examples of these Enriques surfaces together with their canonical coverings. It follows that the classification of all Enriques surfaces with finite automorphism group in any characteristics has been finished.

Some examples of K3 surfaces with infinite automorphism group which preserves an elliptic pencil

We give more details to our examples in [9] of K3 surfaces over C such that they have infinite automorphism group but it preserves some elliptic pencil of the K3

Numerical trivial automorphisms of Enriques surfaces in arbitrary characteristic

We extend to arbitrary characteristic some known results about automorphisms of complex Enriques surfaces that act trivially on the cohomology or the cohomology modulo torsion.

Surface fibrations with large equivariant automorphism group

For a relatively minimal surface fibration $f: X\to C$, the equivariant automorphism group of $f$ is, roughly speaking, the group of automorphisms of $X$ preserving the fibration structure. We present a classification of such fibrations of fibre genus $g\ge 1$ with smooth generic fibre over an arbitrary algebraically closed field $\mathbf{k}$ whose equivariant automorphism group is infinite.

Log del Pezzo surfaces with simple automorphism groups

In this paper we consider del Pezzo surfaces with only log terminal singularities admitting an action of a finite simple group.

On symplectic and non--symplectic automorphisms of K3 surfaces

In this paper we investigate when the generic member of a family of K3 surfaces admitting a non--symplectic automorphism of finite order admits also a symplectic automorphism of the same order. We give a complete answer to this question if the order of the automorphism is a prime number and we provide several examples and partial results otherwise. Moreover we prove that, under certain conditions, a K3 surface admitting a non--symplectic automorphism of prime odd order, $p$, also admits a non--symplectic automorphism of order $2p$. This generalizes a previous result by J. Dillies for $p=3$.

Dynamics on supersingular K3 surfaces and automorphisms of Salem degree 22

In this note we exhibit explicit automorphisms of maximal Salem degree 22 on the supersingular K3 surface of Artin invariant one for all primes p congruent 3 mod 4 in a systematic way. Automorphisms of Salem degree 22 do not lift to any characteristic zero model.

有理三维簇与Kummer曲面的伪自同构

Pseudo-automorphisms of rational threefolds and Kummer surfaces

本文将45个经典Kummer曲面自同构提升为$\mathbb{P}^3$沿6点15线爆破所得三维簇的伪自同构，并描述了由这些已知伪自同构生成的群的基本域。

The automorphism group of the Hilbert scheme of two points on a generic projective K3 surface

We determine the automorphism group of the Hilbert scheme of two points on a generic projective K3 surface of any polarization. We obtain in particular new examples of Hilbert schemes of points having non-natural non-symplectic automorphisms. The existence of these automorphisms depends on solutions of Pell's equation.

Automorphisms of K3 surfaces and their applications

This paper is a survey about $K3$ surfaces with an automorphism and log rational surfaces, in particular, log del Pezzo surfaces and log Enriques surfaces. It is also a reproduction on my talk at "Mathematical structures of integrable systems and their applications" held at Research Institute for Mathematical Sciences in September 2018.

Automorphisms of cubic surfaces in positive characteristic

We classify all possible automorphism groups of smooth cubic surfaces over an algebraically closed field of arbitrary characteristic. As an intermediate step we also classify automorphism groups of quartic del Pezzo surfaces. We show that the moduli space of smooth cubic surfaces is rational in every characteristic, determine the dimensions of the strata admitting each possible isomorphism class of automorphism group, and find explicit normal forms in each case. Finally, we completely characterize when a smooth cubic surface in positive characteristic, together with a group action, can be lift…

Projective Automorphism Groups of Nonsingular Quartic Surfaces

For every p >= 5, we determine all Z_p-invariant nonsingular quartic surfaces in the three dimensional projective space over an algebraically closed field of characteristic zero. In some cases, we also determine their full projective automorphism groups.

K3 surfaces with a non-symplectic automorphism and product-quotient surfaces with cyclic groups

We classify all the K3 surfaces which are minimal models of the quotient of the product of two curves $C_1\times C_2$ by the diagonal action of either the group $\Z/p\Z$ or the group $\Z/2p\Z$. These K3 surfaces admit a non-symplectic automorphism of order $p$ induced by an automorphism of one of the curves $C_1$ or $C_2$. We prove that most of the K3 surfaces admitting a non-symplectic automorphism of order $p$ (and in fact a maximal irreducible component of the moduli space of K3 surfaces with a non-symplectic automorphism of order $p$) are obtained in this way.\\ In addition, we show that o…

Simple abelian varieties and primitive automorphisms of null entropy of surfaces

We characterize simple complex abelian varieties and simple abelian surfaces in terms of primitivity of translation automorphisms. Applying this together with a result due to Diller and Favre, we then classify all primitive birational automorphisms with trivial first dynamical degree of smooth projective surfaces over an algebraically closed field of any characteristic.

Automorphisms of Minimal Surfaces of General Type with $K_S^2 = 1$, $p_g = 2$

We classify the automorphism group of minimal surfaces of general type with $K_S^2 = 1$ and $ρ_g = 2$. Furthermore, we show that the order of the automorphism group is bounded above by 200 and can only have prime factors $p \leq 31$ with $p \neq 29$.

K3 surfaces with an order 60 automorphism and a characterization of supersingular K3 surfaces with Artin invariant 1

In characteristic $p=0$ or $p>5$, we show that a K3 surface with an order 60 automorphism is unique up to isomorphism. As a consequence, we characterize the supersingular K3 surface with Artin invariant 1 in characteristic $p=11$ (mod 12) by a cyclic symmetry of order 60.

The Cayley-Oguiso automorphism of positive entropy on a K3 surface

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 lattice. We show, using results of Beauville, that these surfaces are therefore determinantal quartic surfaces. Long ago, Cayley constructed an automorphism of such determinantal surfaces. We show that Cayley's automorphism coincides with Oguiso's free automorphism. We also exhibit an explicit example of a determinantal quartic whose Picard lattice has exactly rank two and for which we thus have an explicit descript…

Automorphisms of Salem degree 22 on supersingular K3 surfaces of higher Artin invariant

We give a short proof that every supersingular K3 surface (except possibly in characteristic $2$ with Artin invariant $σ=10$) has an automorphism of Salem degree 22. In particular an infinite subgroup of the automorphism group does not lift to characteristic zero. The proof relies on the case $σ=1$ and the cone conjecture for K3 surfaces.

On Riemann surfaces of genus $g$ with $4g-4$ automorphisms

In this article we study compact Riemann surfaces with a non-large group of automorphisms of maximal order; namely, compact Riemann surfaces of genus $g$ with a group of automorphisms of order $4g-4.$ Under the assumption that $g-1$ is prime, we provide a complete classification of them and determine isogeny decompositions of the corresponding Jacobian varieties.

Automorphisms of unnodal Enriques surfaces

It follows from an observation of A. Coble in 1919 that the automorphism group of an unnodal Enriques surface contains the $2$-congruence subgroup of the Weyl group of the $E_{10}$-lattice. In this article, we determine how much bigger the automorphism group of an unnodal Enriques surface can be. Furthermore, we show that the automorphism group is in fact equal to the $2$-congruence subgroup for generic Enriques surfaces in arbitrary characteristic (under the additional assumption that the Enriques surface is ordinary if the characteristic is $2$), improving the corresponding result of W. Bart…

Prime order automorphisms of abelian surfaces: a lattice-theoretic point of view

In this article, we focus on a new perspective of automorphisms of complex 2-tori, reviewing previous works from a lattice-theoretic point of view. In particular, we give a classification of families of symplectic and non-symplectic automorphisms of prime order.

Bi-canonical representations of finite automorphisms acting on Enriques surfaces

We classify the bi-canonical representations of finite automorphisms on Enriques surfaces. There are three types of non-trivial cases and examples are given explicitly by Horikawa models. In particular, finite non-semi-symplectic automorphisms exist only in orders 4 and 8. One corollary is that any finite cyclic subgroup in the automorphism group of an Enriques surface has order 1, 2, 3, 4, 5, 6, 8. Moreover, for two of the three types, a uniqueness theorem for maximal-dimensional families is given.

无点del Pezzo曲面的自同构群

Automorphisms of del Pezzo surfaces without points

本研究聚焦零特征域上无点del Pezzo曲面，探究其自同构群并估计Jordan常数，丰富了代数几何领域相关研究。

Order 6 non-symplectic automorphisms of K3 surfaces

We classify primitive non-symplectic automorphisms of order 6 on K3 surfaces. We show how their study can be reduced to the study of non-symplectic automorphisms of order 3 and to a local analysis of the fixed loci. In particular, we determine the possible fixed loci and show that when the Picard lattice is fixed, K3 surfaces come in mirror pairs.

Cayley K3曲面的希尔伯特概型的自同构群

Automorphisms of Hilbert schemes of Cayley's K3 surfaces

本研究针对皮卡数为2的Cayley K3曲面的希尔伯特平方，证明其自同构群是三个2阶循环群的自由积，生成元为三个Beauville对合，推进了K3曲面希尔伯特概型自同构群的相关研究。

Non-symplectic automorphisms of order 3 on K3 surfaces

In this paper we study K3 surfaces with a non-symplectic automorphism of order 3. In particular, we classify the topological structure of the fixed locus of such automorphisms and we show that it determines the action on cohomology. This allows us to describe the structure of the moduli space and to show that it has three irreducible components.

Picard数为2的K3曲面的自同构的动力次数

Dynamical degrees of automorphisms of K3 surfaces with Picard number 2

本文证明了存在迹为3的Picard数为2的射影K3曲面自同构，并结合已有结果确定了此类曲面自同构的动力次数集合。

关于Severi-Brauer曲面的双有理自同构

On birational automorphisms of Severi-Brauer surfaces

本文显式描述了代数非闭域上非射影平面的Severi-Brauer曲面的双有理自同构群的生成元。

非正规刚性仿射曲面的自同构群是有限维的

Automorphism groups of non-normal rigid affine surfaces are finite-dimensional

本文证明非正规仿射曲面若没有非平凡加法群作用，则其自同构群是有限维的，推广了Perepechko和Zaidenberg关于正规曲面的结果。

Picard数为3的K3曲面的自由自同构群

Free automorphism groups of K3 surfaces with Picard number 3

针对Picard数为3的一类K3曲面，本文研究其自同构群与模群同余子群的同构关系，并证明任意大秩自由群均可实现为该类曲面的自同构群。