On arithmetic Zariski pairs in degree 6

Explicit computations of Zariski decompositions on P_Z^1

In this note, we observe several properties of arithmetic divisors on the projective line over Z and give their Zariski decompositions.

算术度及其在扎里斯基稠密轨道猜想中的应用

Arithmetic degree and its application to Zariski dense orbit conjecture

证明了拟射影簇上支配有理自映射存在算术度接近第一动力度的良定义轨道，并据此证得特定双有理映射（含三维簇上第一动力度>1的情形）满足扎里斯基稠密轨道猜想。

一度del Pezzo曲面与Zariski多重的例子

Del Pezzo surfaces of degree one and examples of Zariski multiples

利用E8韦尔群的单胞作用，研究一度del Pezzo曲面中240条线的Zariski多重构造，探索大N的示例。

Torsion divisors of plane curves with maximal flexes and Zariski pairs

There is a close relationship between the embedded topology of complex plane curves and the (group-theoretic) arithmetic of elliptic curves. In a recent paper, we studied the topology of some arrangements of curves which include a special smooth component, via the torsion properties induced by the divisors in the special curve associated to the remaining components, which is an arithmetic property. When this special curve has maximal flexes, there is a natural isomorphism between its Jacobian variety and the degree zero part of its Picard group. In this paper we consider curve arrangements whi…

Big arithmetic divisors on the projective spaces over Z

This paper is an enhancement of the previous note "Explicit computations of Zariski decompositions on P_Z^1". In this paper, we observe several properties of a certain kind of an arithmetic divisor D on the n-dimensional projective space over Z and give the exact form of the Zariski decomposition of D on the projective line over Z. Further, we show that, if n>=2 and D is big and non-nef, then, for any birational morphism f: X --> P^n_Z of projective, generically smooth and normal arithmetic varieties, we can not expect a suitable Zariski decomposition of f^*(D). We also give a concrete constru…

Triangular curves and cyclotomic Zariski tuples

The purpose of this paper is to exhibit infinite families of conjugate projective curves in a number field whose complement have the same abelian fundamental group, but are non-homeomorphic. In particular, for any $d>3$ we find Zariski tuples parametrized by the $d$-roots of unity up to complex conjugation. As a consequence, for any divisor $m$ of $d$, $m\neq 1,2,3,4,6$, we find arithmetic Zariski $\frac{ϕ(m)}{2}$-tuples with coefficients in the corresponding cyclotomic field. These curves have abelian fundamental group and they are distinguished using a linking invariant.

上同调双曲映射的算术次数与扎里斯基稠密轨道

Arithmetic degrees and Zariski dense orbits of cohomologically hyperbolic maps

本研究针对定义在代数数域代数闭包上的p-上同调双曲有理自映射，探究了算术次数下界、扎里斯基稠密轨道点存在性及预周期点有限性，证明了1-上同调双曲映射的相关性质，并证实算术次数可为超越数。

An arithmetic Zariski pair of line arrangements with non-isomorphic fundamental group

In a previous work, the third named author found a combinatorics of line arrangements whose realizations live in the cyclotomic group of the fifth roots of unity and such that their non-complex-conjugate embedding are not topologically equivalent in the sense that they are not embedded in the same way in the complex projective plane. That work does not imply that the complements of the arrangements are not homeomorphic. In this work we prove that the fundamental groups of the complements are not isomorphic. It provides the first example of a pair of Galois-conjugate plane curves such that the …

通过基本群得到的7次和8次圆锥-直线构型的Zariski对

Zariski pairs of conic-line arrangements of degrees 7 and 8 via fundamental groups

通过基本群和Zariski-van Kampen定理，发现新的8次圆锥-直线构型Zariski对，并验证了2014年提出的两个7次Zariski对。

Geometry of bisections of elliptic surfaces and Zariski $N$-plets II

In this article, we continue to study the geometry of bisections of certain rational elliptic surfaces. As an application, we give examples of Zariski N + 1-plets of degree 2N + 4 whose irreducible components are an irreducible quartic curve with 2 nodes and N smooth conics. Furthermore, by considering the case of N = 2 and combining with known results, a new Zariski 5-plet for reduced plane curves of degree 8 is given.

Del Pezzo surfaces of degree four violating the Hasse principle are Zariski dense in the moduli scheme

We show that, over every number field, the degree four del Pezzo surfaces that violate the Hasse principle are Zariski dense in the moduli scheme.

Arithmetic degrees and dynamical degrees of endomorphisms on surfaces

For a dominant rational self-map on a smooth projective variety defined over a number field, Kawaguchi and Silverman conjectured that the (first) dynamical degree is equal to the arithmetic degree at a rational point whose forward orbit is well-defined and Zariski dense. We prove this conjecture for surjective endomorphisms on smooth projective surfaces. For surjective endomorphisms on any smooth projective varieties, we show the existence of rational points whose arithmetic degrees are equal to the dynamical degree. Moreover, we prove that there exists a Zariski dense set of rational points h…

Alexander-equivalent Zariski pairs of irreducible sextics

The existence of Alexander-equivalent Zariski pairs dealing with irreducible curves of degree 6 was proved by A. Degtyarev. However, up to now, no explicit example of such a pair was available (only the existence was known). In this paper, we construct the first concrete example.

Lattice Zariski k-ples of plane sextic curves and Z-splitting curves for double plane sextics

A simple sextic is a reduced complex projective plane curve of degree 6 with only simple singularities. We introduce a notion of Z-splitting curves for the double covering of the projective plane branching along a simple sextic, and investigate lattice Zariski k-ples of simple sextics by Z-splitting curves. We define specialization of lattice types, and classify all lattice types of Z-splitting curves of degree less than or equal to 3 up to specializations.

Mordell-Weil群与Zariski三元组

Mordell-Weil groups and Zariski triples

本文构造了三条12次不可约曲线，它们尖点数相同但Alexander多项式不同，从而给出Zariski三元组的新例子，并进一步研究了相关椭圆三维流形的Mordell-Weil群生成元及一般基变换下等奇异变形空间的维数。

Arithmetic behaviour of Frobenius semistability of syzygy bundles for plane trinomial curves

Here we consider the set of bundles $\{V_n\}_{n\geq 1}$ associated to the plane trinomial curves $k[x,y,z]/(h)$. We prove that the Frobenius semistability behaviour of the reduction mod $p$ of $V_n$ is a function of the congruence class of $p$ modulo $2λ_h$ (an integer invariant associated to $h$). As one of the consequences of this, we prove that if $V_n$ is semistable in characteristic 0, then its reduction mod $p$ is strongly semistable, for $p$ in a Zariski dense set of primes. Moreover, for any given finitely many such semistable bundles $V_n$, there is a common Zariski dense set of such …

Non-homeomorphic conjugate complex varieties

We present a method to produce examples of non-homeomorphic conjugate complex varieties based on the genus theory of lattices. As an application, we give examples of arithmetic Zariski pairs.

The matroid structure of vectors of the Mordell-Weil lattice and the topology of plane quartics and bitangent lines

In this paper, we introduce the terminology of matroids into the study of Zariski-pairs related to rational elliptic surfaces, aiming to simplify the presentation and arguments involved. As an application, we provide new examples of Zariski $N$-ples of relatively low degree. Namely we show that a Zariski 102-ple of degree 18 exists.

On Zariski Multiplets of Branch Curves from Surfaces Isogenous to a Product

In this paper we give an asymptotic bound of the cardinality of Zariski multiples of particular plane singular curves. These curves have only nodes and cusps as singularities and are obtained as branched curves of ramified covering of the plane by surfaces isogenous to a product of curves with group $(\mathbb{Z}/2\mathbb{Z})^k$. The knowledge of the moduli space of these surfaces will enable us to produce Zariski multiplets whose number grows subexponentialy in function of their degree.

Zariski multiples associated with quartic curves

We investigate Zariski multiples of plane curves $Z_1, \dots, Z_N$ such that each $Z_i$ is a union of a smooth quartic curve, some of its bitangents, and some of its 4-tangent conics. We show that, for plane curves of this type, the deformation types are equal to the homeomorphism types, and that the number of deformation types grows as $O(d^{62})$ when the degree $d$ of the plane curves tends to infinity.

Torsion divisors of plane curves and Zariski pairs

In this paper we study the embedded topology of reducible plane curves having a smooth irreducible component. In previous studies, the relation between the topology and certain torsion classes in the Picard group of degree zero of the smooth component was implicitly considered. We formulate this relation clearly and give a criterion for distinguishing the embedded topology in terms of torsion classes. Furthermore, we give a method of systematically constructing examples of curves where our criterion is applicable, and give new examples of Zariski tuples.

某个7次圆锥曲线-直线排列的实现空间与一个π₁等价Zariski对

The realization space of a certain conic line arrangement of degree 7 and a $π_1$-equivalent Zariski pair

本文通过构造一个π₁等价Zariski对，确定了具有特定固定组合结构的7次圆锥曲线-直线排列实现空间的连通分支数。

Hilbert Functions and the Finite Degree Zariski Closure in Finite Field Combinatorial Geometry

The polynomial method has been used recently to obtain many striking results in combinatorial geometry. In this paper, we use affine Hilbert functions to obtain an estimation theorem in finite field geometry. The most natural way to state the theorem is via a sort of bounded degree Zariski closure operation: given a set, we consider all polynomials of some bounded degree vanishing on that set, and then the common zeros of these polynomials. For example, the degree d closure of d + 1 points on a line will contain the whole line, as any polynomial of degree at most d vanishing on the d + 1 point…

A note on splitting numbers for Galois covers and $π_1$-equivalent Zariski $k$-plets

In this paper, we introduce \textit{splitting numbers} of subvarieties in a smooth variety for a Galois cover, and prove that the splitting numbers are invariant under certain homeomorphisms. By splitting numbers, we give a necessary and sufficient condition for two plane curves of type $(b,m)$ to be topologically equivalent as pairs of the complex projective plane and plane curves, where a plane curve of type $(b,m)$ is an arrangement of two smooth plane curves of degree $3$ and $b$ defined by I.~Shimada. Consequently, we prove that there are $π_1$-equivalent Zariski $k$-plets for any $k\geq2…

On the degree of caustics of reflection

Given a point S and any irreducible algebraic curve C in P^2 (with any type of singularities), we consider the caustic of reflection defined as the Zariski closure of the envelope of the reflected lines from the point S on the curve C. We identify this caustic with the Zariski closure of the image of C by a rational map. Thanks to a general fundamental lemma, we give a formula for the degree of the caustic of reflection in terms of multiplicity numbers of C (or of its branches). Our formula holds in every case. We also give some precisions about Plücker formulas.

算术次数是上同调 Lyapunov 乘子

Arithmetic Degrees are Cohomological Lyapunov Multipliers

本文证明射影簇自同态中 Zariski 稠密轨道点的算术次数必为系统的上同调 Lyapunov 乘子，并据此得到动力 Mordell–Lang 猜想的推论。

On Zariski's multiplicity problem at infinity

We address a metric version of Zariski's multiplicity conjecture at infinity that says that two complex algebraic affine sets which are bi-Lipschitz homeomorphic at infinity must have the same degree. More specifically, we prove that the degree is a bi-Lipschitz invariant at infinity when the bi-Lipschitz homeomorphism has Lipschitz constants close to 1. In particular, we have that a family of complex algebraic sets bi-Lipschitz equisingular at infinity has constant degree. Moreover, we prove that if two polynomials are weakly rugose equivalent at infinity, then they have the same degree. In p…

反Zariski对

Anti-Zariski pairs

提出反Zariski对概念，即同胚但属于等奇异族不同分支的平面曲线对，并给出例子及相关讨论。

A note on Zariski pairs

A couple of complex projective plane curves are said to make a Zariski pair if they have the same degree and the same type of singularities, but their embeddings in the projective plane are topologically different. In this paper, we present a method to construct certain type of Zariski pairs, and make infinite series of examples.

弱接触圆锥与具有2个节点和1个尖点的不可约四次曲线的几何学 via 理性椭圆面和扎里斯基对

Geometry of weak contact conics to irreducible quartics with 2 nodes and 1 cusp via rational elliptic surfaces and Zariski pairs

研究弱接触圆锥与具有2个节点和1个尖点的不可约四次曲线的几何结构，通过理性椭圆面和扎里斯基对构造度数为7和8的扎里斯基对。

Non-density of points of small arithmetic degrees

Given a surjective endomorphism $f: X \to X$ on a projective variety over a number field, one can define the arithmetic degree $α_f(x)$ of $f$ at a point $x$ in $X$. The Kawaguchi - Silverman Conjecture (KSC) predicts that any forward $f$-orbit of a point $x$ in $X$ at which the arithmetic degree $α_f(x)$ is strictly smaller than the first dynamical degree $δ_f$ of $f$ is not Zariski dense. We extend the KSC to sAND (= small Arithmetic Non-Density) Conjecture that the locus $Z_f(d)$ of all points of small arithmetic degree is not Zariski dense, and verify this sAND Conjecture for endomorphisms…

Dynamical Degree and Arithmetic Degree of Endomorphisms on Product Varieties

For a dominant rational self-map on a smooth projective variety defined over a number field, Shu Kawaguchi and Joseph H. Silverman conjectured that the dynamical degree is equal to the arithmetic degree at a rational point whose forward orbit is well-defined and Zariski dense. We give some examples of self-maps on product varieties and rational points on them for which the Kawaguchi-Silverman conjecture holds.

含唯一圆锥曲线的圆锥曲线-直线排列的Zariski对

Zariski pairs of conic-line arrangements with a unique conic

本研究提出两对9次、含唯一圆锥曲线的圆锥曲线-直线排列构成的Zariski对，通过连通数区分二者的拓扑结构。

关于判别次数为八的锥面的不可理化性

On the unirationality of conic bundles with discriminant of degree eight

本文研究了判别次数为八的锥面的不可理化性，通过构造有理多截面和变形理论分析，揭示了其在不同域上的不可理化性质。

On the Variety of Rational Curves of Degree $d$ in $\Bbb P^n$

We construct the canonical structure of an irreducible projective variety on the set of connected curves of degree $d$ in $\Bbb P^n$ with rational components (some components can be multiple). The set of rational curves is open subset in the Zariski topology under this structure.

$\mathbb{P}^3$ 的一个 $1$-上同调双曲双有理映射，具有超越算术度

A $1$-cohomologically hyperbolic birational map of $\mathbb{P}^3$, with a transcendental arithmetic degree

构造 $\mathbb{P}^3$ 上 $1$-上同调双曲双有理映射，其第一动力次数与在代数闭包点上的算术度均为超越数。

7次和8次圆锥-直线构型的强Ziegler对示例

Examples of strong Ziegler pairs of conic-line arrangements of degree 7 and 8

本文证明了某些具有相同组合结构但嵌入拓扑不同的平面曲线对（Zariski对）同时也是Milnor代数不同构的强Ziegler对。

On arithmetic inequalities for points of bounded degree

We study algebraic points of bounded degree on polarized projective varieties. To do so, we refine further the filtration construction and Subspace Theorem approach, for the study of integral points, which has origins in the work of Corvaja-Zannier, Levin, Evertse and Autissier. Our main result shows how a conjecture of H.~P.~Schlickewei implies Second Main Arithmetic Schmidt's Subspace type inequalities for polarized projective varieties and points of bounded degree.

On the realizability of arithmetic degrees of morphisms

The Kawaguchi-Silverman conjecture relates two different invariants of a surjective endomorphism, the dynamical and arithmetic degrees. As the Kawaguchi-Silverman conjecture is only meaningful when a morphism has a Zariski dense orbit, it has no content for varieties with positive Kodaira dimension. A generalization of the Kawaguchi-Silverman conjecture which is meaningful in positive Kodaira dimension is the so called sAND conjecture, which involves the set of "small" arithmetic degrees. Kawaguchi and Silverman showed that a small arithmetic degree is the modulus of an eigenvalue of $f^*\colo…

96120: The degree of the linear orbit of a cubic surface

The projective linear group \(\pgl(\comp,4)\) acts on cubic surfaces, considered as points of $\mathbb{P}_{\mathbb{C}}^{19}$. We compute the degree of the $15$-dimensional projective variety given by the Zariski closure of the orbit of a general cubic surface. The result, 96120, is obtained using methods from numerical algebraic geometry.

Zeta-function and $μ^*$-Zariski pairs of surfaces

A Zariski pair of surfaces is a pair of complex polynomial functions in $\mathbb{C}^3$ which is obtained from a classical Zariski pair of projective curves $f_0(z_1,z_2,z_3)=0$ and $f_1(z_1,z_2,z_3)=0$ of degree $d$ in $\mathbb{P}^2$ by adding a same term of the form $z_i^{d+m}$ ($m\geq 1$) to both $f_0$ and $f_1$ so that the corresponding affine surfaces of $\mathbb{C}^3$ -- defined by $g_0:=f_0+z_i^{d+m}$ and $g_1:=f_1+z_i^{d+m}$ -- have an isolated singularity at the origin and the same zeta-function for the monodromy associated with their Milnor fibrations (so, in particular, $g_0$ and $g_…

On $ μ$-Zariski pairs of links

The notion of Zariski pairs for projective curves in $\mathbb P^2$ is known since the pioneer paper of Zariski \cite{Zariski} and for further development, we refer the reference in \cite{Bartolo}.In this paper, we introduce a notion of Zariski pair of links in the class of isolated hypersurface singularities. Such a pair is canonically produced from a Zariski (or a weak Zariski ) pair of curves $C=\{f(x,y,z)=0\}$ and $C'=\{g(x,y,z)=0\}$ of degree $d$ by simply adding a monomial $z^{d+m}$ to $f$ and $g$ so that the corresponding affine hypersurfaces have isolated singularities at the origin. Th…

Arithmetic and Dynamical Degrees on Abelian Varieties

Let $ϕ:X\dashrightarrow X$ be a dominant rational map of a smooth variety and let $x\in X$, all defined over $\bar{\mathbb Q}$. The dynamical degree $δ(ϕ)$ measures the geometric complexity of the iterates of $ϕ$, and the arithmetic degree $α(ϕ,x)$ measures the arithmetic complexity of the forward $ϕ$-orbit of $x$. It is known that $α(ϕ,x)\leδ(ϕ)$, and it is conjectured that if the $ϕ$-orbit of $x$ is Zariski dense in $X$, then $α(ϕ,x)=δ(ϕ)$, i.e., arithmetic complexity equals geometric complexity. In this note we prove this conjecture in the case that $X$ is an abelian variety, extending earl…

On the arithmetic of weighted complete intersections of low degree

A variety is rationally connected if two general points can be joined by a rational curve. A higher version of this notion is rational simple connectedness, which requires suitable spaces of rational curves through two points to be rationally connected themselves. We prove that smooth, complex, weighted complete intersections of low enough degree are rationally simply connected. This result has strong arithmetic implications for weighted complete intersections defined over the function field of a smooth, complex curve. Namely, it implies that these varieties satisfy weak approximation at all p…

关于Zariski稠密轨道猜想的一个注记

A note on Zariski dense orbit conjecture

本文给出Zariski稠密轨道猜想的一个注记，简化了射影三维簇自同构的ZDO结果，并证明了不规则度足够大的射影簇的ZDO成立。

拟射影簇的自同态——走向Zariski稠密轨道与Kawaguchi-Silverman猜想

Endomorphisms of quasi-projective varieties -- towards Zariski dense orbit and Kawaguchi-Silverman conjectures

本文研究了拟射影簇上有限满射自同态的Zariski稠密轨道猜想（ZDO）、Adelic Zariski稠密轨道猜想（AZO）及Kawaguchi-Silverman猜想（KSC），并在光滑仿射曲面、射影簇和半阿贝尔簇等特定条件下证明了这些猜想成立。

Higher arithmetic degrees of dominant rational self-maps

Suppose that $f \colon X \dashrightarrow X$ is a dominant rational self-map of a smooth projective variety defined over ${\overline{\mathbf Q}}$. Kawaguchi and Silverman conjectured that if $P \in X({\overline{\mathbf Q}})$ is a point with well-defined forward orbit, then the growth rate of the height along the orbit exists, and coincides with the first dynamical degree $λ_1(f)$ of $f$ if the orbit of $P$ is Zariski dense in $X$. In this note, we extend the Kawaguchi-Silverman conjecture to the setting of orbits of higher-dimensional subvarieties of $X$. We begin by defining a set of arithmeti…

Linear Spaces of Symmetric Matrices with Non-Maximal Maximum Likelihood Degree

We study the maximum likelihood degree of linear concentration models in algebraic statistics. We relate the geometry of the reciprocal variety to that of semidefinite programming. We show that the Zariski closure in the Grassmanian of the set of linear spaces that do not attain their maximal possible maximum likelihood degree coincides with the Zariski closure of the set of linear spaces defining a projection with non-closed image of the positive semidefinite cone. In particular, this shows that this closure is a union of coisotropic hypersurfaces.

A Non-Standard Bezout Theorem

This paper provides a non-standard analogue of Bezout's theorem. This is acheived by showing that, in all characteristics, the notion of Zariski multiplicity coincides with intersection multiplicity when we consider the full families of projective degree d and degree e curves. The result is particularly interesting in that it holds even when we consider intersections at singular points of curves or when the curves contain non-reduced components. The proof also provides motivation for the fact that tangency is a definable relation for families of curves inside a non-linear 1-dimensional Zariski…

Periodic points of birational maps on projective surfaces

We classify birational maps of projective smooth surfaces whose non-critical periodic points are Zariski dense. In particular, we show that if the first dynamical degree is greater than one, then the periodic points are Zariski dense.

On irreducibility of the family of ACM curves of degree 8 and genus 4 in $P^4_k$

Let C be an arithmetically Cohen-Macaulay curve of arithmetic genus 4. We prove that the family of such curves of degree 8 in $P^4_k$ is irreducible.

Potential density of projective varieties having an int-amplified endomorphism

We consider the potential density of rational points on an algebraic variety defined over a number field $K$, i.e., the property that the set of rational points of $X$ becomes Zariski dense after a finite field extension of $K$. For a non-uniruled projective variety with an int-amplified endomorphism, we show that it always satisfies potential density. When a rationally connected variety admits an int-amplified endomorphism, we prove that there exists some rational curve with a Zariski dense forward orbit, assuming the Zariski dense orbit conjecture in lower dimensions. As an application, we p…

Arithmetic degrees for dynamical systems over function fields of characteristic zero

We study arithmetic degree of a dominant rational self-map on a smooth projective variety over a function field of characteristic zero. We see that the notion of arithmetic degree and some related problems over function fields are interpreted into geometric ones. We give another proof of the theorem that the arithmetic degree at any point is smaller than or equal to the dynamical degree. We give a sufficient condition for an arithmetic degree to coincide with the dynamical degree, and prove that any self-map has so many points whose arithmetic degrees are equal to the dynamical degree. We stud…

某些有理自映射的周期点与算术度

Periodic points and arithmetic degrees of certain rational self-maps

本文研究代数数域上的上同调双曲双有理自映射，给出其周期点高度的有界性结果，还将二维有理自映射的Kawaguchi--Silverman猜想归约为动力Mordell--Lang猜想，验证了若干新情形并证明对应Zariski稠密轨道存在。