Kobayashi hyperbolicity of almost complex manifolds

On the Kobayashi hyperbolicity of certain tube domains

In an earlier article the second author introduced three families of tube domains in ${\mathbf C}^2$ with holomorphic automorphism group isomorphic to ${\mathbf R}\ltimes{\mathbf R}^2$ and envelope of holomorphy equal to ${\mathbf C}^2$. In the present paper we show that every domain in each of these families is Kobayashi-hyperbolic.

Riemann 流形中的 Kobayashi 双曲性

Kobayashi hyperbolicity in Riemannian manifolds

本文研究 Riemann 流形中区域的 Kobayashi–Royden 度量边界行为与 Kobayashi 双曲性，并据此证明共形调和浸入圆盘的 Fatou 型非切向极限定理及 Picard 定理，同时给出双曲流形示例。

Sharp estimates of the Kobayashi metric and Gromov hyperbolicity

Let D be a smooth relatively compact and strictly J-pseudoconvex domain in a four dimensional almost complex manifold (M,J). We give sharp estimates of the Kobayashi metric. Our approach is based on an asymptotic quantitative description of both the domain D and the almost complex structure J near a boundary point. Following Z.M.Balogh and M.Bonk, these sharp estimates provide the Gromov hyperbolicity of the domain D.

重新审视平面域上的 Kobayashi 超曲性

Revisiting Kobayashi hyperbolicity on planar domains

本文通过两个新方法证明了双孔复平面上的完全 Kobayashi 超曲性，并给出了有界域的简洁证明。同时应用这些结果证明了 Landau、Schottky 和 Picard 经典定理。

C^2 中有限型拟凸域上的 Kobayashi 度量与 Gromov 双曲性

The Kobayashi metric and Gromov hyperbolicity on pseudoconvex domains of finite type in $\mathbb{C}^2$

本文改进了 C^2 中光滑有界有限型拟凸域的 Catlin 型距离估计，并据此给出该域在 Kobayashi 距离下具有 Gromov 双曲性的新证明。

阿贝尔簇上完全线性系统的小舟超曲率

Kobayashi hyperbolicity of complete linear systems on abelian varieties

研究阿贝尔簇上完全线性系统中非常一般元素的柯拜ashi超曲率条件，并提出相关猜想。

On the Gromov hyperbolicity of convex domains in Cn

We give a necessary complex geometric condition for a bounded smooth convex domain in Cn, endowed with the Kobayashi distance, to be Gromov hyperbolic. More precisely, we prove that if a smooth bounded convex domain contains an analytic disk in its boundary, then the domain is not Gromov hyperbolic for the Kobayashi distance. We also provide examples of bounded smooth convex domains that are not strongly pseudoconvex but are Gromov hyperbolic.

Gromov hyperbolicity of pseudo-convex Levi corank one domains

After a study of the Kobayashi metrics on certain scaled domains, we show the stabilities of the infinitesimal Kobayashi metrics and the integrated distances in different scaling processes. As an application, we prove that bounded pseudo-convex domains of finite type where the Levi form of every boundary point has corank one are Gromov hyperbolic with respect to the Kobayashi metric. The results in this note generalize Zimmer's and Fiacchi's related works on Gromov hyperbolicity of weakly pseudo-convex domains.

Analytic stacks and hyperbolicity

The classical Brody's theorem asserts the equivalence between two notions of hyperbolicity for compact complex spaces, one named after Kobayashi and one expressed in terms of lack of non constant holomorphic entire functions (compactness is only used to prove the harder implication). We extend this theorem to Deligne-Mumford analytic stacks, by first providing definitions of what we think of Kobayashi and Brody hyperbolicity for such objects and then proving the equivalence of these concepts under an assumption of compactness.

Regularity of complex geodesics and (non)-Gromov hyperbolicity of convex tube domains

We deliver examples of non-Gromov hyperbolic tube domains with convex bases (equipped with the Kobayashi distance). This is shown by providing a criterion on non-Gromov hyperbolicity of (non-smooth) domains.The results show the similarity of geometry of the bases of non-Gromov hyperbolic tube domains with the geometry of non-Gromov hyperbolic convex domains. A connection between the Hilbert metric of a convex domain $Ω$ in $\mathbb R^n$ with the Kobayashi distance of the tube domain over the domain $Ω$ is also shown. Moreover, continuity properties up to the boundary of complex geodesics in tu…

Gromov hyperbolicity and the Kobayashi metric on "convex" sets

In this paper we study the global geometry of the Kobayashi metric on "convex" sets. We provide new examples of non-Gromov hyperbolic domains in $\mathbb{C}^n$ of many kinds: pseudoconvex and non-pseudocon \newline -vex, bounded and unbounded. Our first aim is to prove that if $Ω$ is a bounded weakly linearly convex domain in $\mathbb{C}^n,\,n\geq 2,$ and $S$ is an affine complex hyperplane intersecting $Ω,$ then the domain $Ω\setminus S$ endowed with the Kobayashi metric is not Gromov hyperbolic (Theorem 1.3). Next we localize this result on Kobayashi hyperbolic convex domains. Namely, we sho…

Gromov hyperbolicity, the Kobayashi metric, and $\mathbb{C}$-convex sets

In this paper we study the global geometry of the Kobayashi metric on domains in complex Euclidean space. We are particularly interested in developing necessary and sufficient conditions for the Kobayashi metric to be Gromov hyperbolic. For general domains, it has been suggested that a non-trivial complex affine disk in the boundary is an obstruction to Gromov hyperbolicity. This is known to be the case when the set in question is convex. In this paper we first extend this result to $\mathbb{C}$-convex sets with $C^1$-smooth boundary. We will then show that some boundary regularity is necessar…

Kobayashi hyperbolicity, negativity of the curvature and positivity of the canonical bundle

This survey article mainly addresses to graduate students and young researchers in complex geometry willing to enter the beautiful word of connections between curvature and Kobayashi hyperbolicity. It is a detailed account of a recent breakthrough by Wu and Yau, shortly after generalized by Tosatti and Yang (and others), which sits on the crossroad between complex differential geometry and Kobayashi hyperbolicity. More specifically, an old conjecture by Kobayashi, stated at the very beginning of the theory, predicts that a compact hyperbolic manifold should have ample canonical bundle. Now, on…

Kobayashi hyperbolicity of the complements of general hypersurfaces of high degree

In this paper, we prove that in any projective manifold, the complements of general hypersurfaces of sufficiently large degree are Kobayashi hyperbolic. We also provide an effective lower bound on the degree. This confirms a conjecture by S. Kobayashi in 1970. Our proof, based on the theory of jet differentials, is obtained by reducing the problem to the construction of a particular example with strong hyperbolicity properties. This approach relies the construction of higher order logarithmic connections allowing us to construct logarithmic Wronskians. These logarithmic Wronskians are the buil…

Pseudo Kobayashi hyperbolicity of base spaces of families of minimal projective manifolds with maximal variation

In this paper we prove that every quasi-projective base space $V$ of smooth family of minimal projective manifolds with maximal variation is pseudo Kobayashi hyperbolic, i.e. $V$ is Kobayashi hyperbolic modulo a proper subvariety $Z\subsetneq V$. In particular, $V$ is algebraically degenerate, that is, every nonconstant entire curve $f:\mathbb{C}\to V$ has image $f(\mathbb{C})$ which lies in that proper subvariety $Z\subsetneq V$. As a direct consequence, we prove the Brody hyperbolicity of moduli spaces of minimal projective manifolds, which answers a question by Viehweg-Zuo in 2003.

由等周不等式导出的内蕴度量的Gromov双曲性

Gromov hyperbolicity of intrinsic metrics from isoperimetric inequalities

本文利用线性等周不等式刻画Gromov双曲性，证明具有边界扩张性质的Kobayashi、Hilbert及极小度量均为Gromov双曲，并给出新证明及极小度量双曲凸域的刻画。

关于Kobayashi距离的局部与全局可见性及Gromov双曲性区域

Local and global visibility and Gromov hyperbolicity of domains with respect to the Kobayashi distance

本文在$\mathbb C^d$中引入局部可见与局部Gromov双曲域概念，证明有界域的局部与全局性质等价，从而可通过边界局部信息检测Gromov双曲性及双全纯映射的连续延拓性。

关于螺旋形圆状域的双曲性

On Hyperbolicity of Spirallike Circularlike domain

本文证明了螺旋形圆状域的Kobayashi双曲性与其核心为空及有界性等价，并提出了一个相关问题。

Proof of the Kobayashi conjecture on the hyperbolicity of very general hypersurfaces

The Green-Griffiths-Lang conjecture stipulates that for every projective variety $X$ of general type over ${\mathbb C}$, there exists a proper algebraic subvariety of $X$ containing all non constant entire curves $f:{\mathbb C}\to X$. Using the formalism of directed varieties, we prove here that this assertion holds true in case $X$ satisfies a strong general type condition that is related to a certain jet-semistability property of the tangent bundle $T\_X$. We then use this fact to confirm a long-standing conjecture of Kobayashi (1970), according to which a very general algebraic hypersurface…

Injective Hyperbolicity for quotients of balls and polydisks

In this article we study the injective Kobayashi metric on complex surfaces.

Kobayashi 度量局部 Gromov 双曲性对边界类型的最优线性依赖

Optimal Linear Dependence on Boundary Type for Local Gromov Hyperbolicity of the Kobayashi Metric

本文证明 Kobayashi 度量局部 Gromov 双曲常数对边界 D'Angelo 型的最优普适依赖是线性的，并指出全局情形无类似界。

Estimates of the Kobayashi metric on almost complex manifolds

We establish a lower estimate for the Kobayashi-Royden infinitesimal pseudometric on an almost complex manifold $(M,J)$ admitting a bounded strictly plurisubharmonic function. We apply this result to study the boundary behaviour of the metric on a strictly pseudoconvex domain in $M$ and to give a sufficient condition for the complete hyperbolicity of a domain in $(M,J)$. Finally we obtain the regularity up to the bounday of $J$-holomorphic discs attached to a totally real submanifold in $M$.

On the logarithmic Kobayashi conjecture

We study the hyperbolicity of the log variety $(\mathbb{P}^n, X)$, where $X$ is a very general hypersurface of degree $d\geq 2n+1$ (which is the bound predicted by the Kobayashi conjecture). Using a positivity result for the sheaf of (twisted) logarithmic vector fields, which may be of independent interest, we show that any log-subvariety of $(\mathbb{P}^n, X)$ is of log-general type, give a new proof of the algebraic hyperbolicity of $(\mathbb{P}^n, X)$, and exclude the existence of maximal rank families of entire curves in the complement of the universal degree $d$ hypersurface. Moreover, we…

Hyperbolicity in unbounded convex domains

We provide several equivalent characterizations of Kobayashi hyperbolicity in unbounded convex domains in terms of peak and anti-peak functions at infinity, affine lines, Bergman metric and iteration theory.

全纯辛簇的非双曲性

Non-hyperbolicity of holomorphic symplectic varieties

本文证明了满足有理SYZ猜想的第二贝蒂数至少为5的本原辛簇的非双曲性，并进一步在第二贝蒂数至少为7时建立了Kobayashi伪度量恒为零的结果，从而完成了Kamenova-Lu-Verbitsky的工作。

On the hyperbolicity of base spaces for maximally variational families of smooth projective varieties

For smooth families with maximal variation, whose general fibers have semi-ample canonical bundle, the generalized Viehweg hyperbolicity conjecture states that the base spaces of such families are of log general type. This deep conjecture was recently proved by Popa-Schnell using the theory of Hodge modules and a theorem by Campana-Păun. In this paper we prove that those base spaces are pseudo Kobayashi hyperbolic, as predicted by the Lang conjecture: any complex quasi-projective manifold is pseudo Kobayashi hyperbolic if it is of log general type. As a consequence, we prove the Brody hyperbol…

Applications of computational invariant theory to Kobayashi hyperbolicity and to Green-Griffiths algebraic degeneracy

A major unsolved problem (according to Demailly 1997) towards the Kobayashi hyperbolicity conjecture in optimal degree is to understand jet differentials of germs of holomorphic discs that are invariant under any reparametrization of the source. The underlying group action is not reductive, but we provide a complete algorithm to generate all invariants, in arbitrary dimension n and for jets of arbitrary order k. Two main new situations are studied in great details. For jets of order 4 in dimension 4, we establish that the algebra of Demailly-Semple invariants is generated by 2835 polynomials, …

Effectivity in the Hyperbolicity-related problems

The aim of this work is to deal with effective questions related to the Kobayashi and Debarre conjectures, and based on the work of Damian Brotbek and Lionel Darondeau. We first show that if a line bundle $L$ generates $k$-jets, the $k$-th Wronskian ideal sheaf associated with global sections of $L$ reaches its largest possible value. Then we obtain an effective estimate for a weaker version of a theorem of Nakamaye on certain universal Grassmannians. We finally derive from this explicit effective bounds for the Kobayashi and Debarre conjectures.

Non-Degeneracy of Kobayashi Volume Measures for Singular Directed Varieties

In this note, we prove the generic Kobayashi volume measure hyperbolicity of singular directed varieties $(X, V)$, as soon as the canonical sheaf $\mathcal{K}\_V$ of $V$ is big in the sense of Demailly.

一般曲面的Kobayashi双曲性：基于Poincaré问题

Kobayashi Hyperbolicity of General Surfaces via the Poincaré Problem

通过Poincaré问题与2-jet微分叶状结构，证明$\mathbb{P}^3$中次数至少18的一般曲面无有理或椭圆曲线，进而建立其Kobayashi双曲性，并推广到平面曲线补集。

Hyperbolicity of coarse moduli spaces and isotriviality for certain families

In this paper, we prove the Kobayashi hyperbolicity of the coarse moduli spaces of canonically polarized or polarized Calabi-Yau manifolds in the sense of complex $V$-spaces (a generalization of complex $V$-manifolds in the sense of Satake). As an application, we prove the following hyperbolic version of Campana's isotriviality conjecture: for the smooth family of canonically polarized or polarized Calabi-Yau manifolds, when the Kobayashi pseudo-distance of the base vanishes identically, the family must be isotrivial, that is, any two fibers are isomorphic. We also prove that for the smooth pr…

Characterization of cycle domains via Kobayashi hyperbolicity

A real form $G$ of a complex semisimple Lie group $G^C$ has only finitely many orbits in any given $G^C$-flag manifold $Z=G^C/Q$. The complex geometry of these orbits is of interest, e.g., for the associated representation theory. The open orbits $D$ generally possess only the constant holomorphic functions, and the relevant associated geometric objects are certain positive-dimensional compact complex submanifolds of $D$ which, with very few well-understood exceptions, are parameterized by the Wolf cycle domains $Ω_W(D)$ in $G^C/K^C$, where $K$ is a maximal compact subgroup of $G$. Thus, for t…

About the hyperbolicity of complete intersections

This note is an extended version of a thirty minutes talk given at the "XIX Congresso dell'Unione Matematica Italiana", held in Bologna from September 12th to September 17th, 2011. This was essentially a survey talk about connections between Kobayashi hyperbolicity properties and positivity properties of the canonical bundle of projective algebraic varieties.

SKT双曲与Gauduchon双曲紧复流形

SKT Hyperbolic and Gauduchon Hyperbolic Compact Complex Manifolds

本文为紧复流形引入SKT双曲性与Gauduchon双曲性，证明前者蕴含Kobayashi/Brody双曲性，后者蕴含除子双曲性，并给出SKT双曲流形万有覆盖上L^2调和空间的消失定理。

Hyperbolicity of general deformations

We present two methods of constructing low degree Kobayashi hyperbolic hypersurfaces in the projective space: the projection method and the deformation method. The talk is based on joint works of the speaker with B. Shiffman and C. Ciliberto.

Gromov (non)hyperbolicity of certain domains in $\mathbb{C}^{2}$

We prove the non-hyperbolicity of the Kobayashi distance for $\mathcal{C}^{1,1}$-smooth convex domains in $\mathbb{C}^{2}$ which contain an analytic disc in the boundary or have a point of infinite type with rotation symmetry. Moreover, examples of smooth, non pseudoconvex, Gromov hyperbolic domains are given; we prove that the symmetrized polydisc and the tetrablock are not Gromov hyperbolic and write down some results about Gromov hyperbolicity of product spaces.

拟正则曲线的重标度原理及其在双曲性中的应用

A rescaling principle for quasiregular curves with applications to hyperbolicity

研究拟正则曲线到校准流形的重标度原理，通过引入适应设定的布罗迪双曲性等方法，证明了相关等价性，量化了局部连续性模，回答了问题并构造新例子给出布罗迪双曲性障碍。

通过数值不变量研究复流形的定量双曲性

Quantitative hyperbolicity for complex manifolds via numerical invariants

研究通过引入双曲指标这一数值不变量来研究复流形的双曲性，结合喷流微分和密度流方法，证明了\(\mathbb{P}^{n + 1}\)中一般超曲面\(X_d\)双曲指标随\(d\)至少线性增长趋于无穷，并讨论了小林猜想的解析方法。

A survey on hyperbolicity of projective hypersurfaces

These are lecture notes of a course held at IMPA, Rio de Janiero, in september 2010: the purpose was to present recent results on Kobayashi hyperbolicity in complex geometry. Our ultimate goal is to describe the results obtained on questions related to the geometry of entire curves traced in generic complex projective hypersurfaces of high degree. For the convenience of the reader, this survey tries to be as self contained as possible.

On hyperbolicity of SU(2)-equivariant, punctured disc bundles over the complex affine quadric

Given a holomorphic line bundle over the complex affine quadric $Q^2$, we investigate its Stein, SU(2)-equivariant disc bundles. Up to equivariant biholomorphism, these are all contained in a maximal one, say $Ω_{max}$. By removing the zero section to $Ω_{max}$ one obtains the unique Stein, SU(2)-equivariant, punctured disc bundle over $Q^2$ which contains entire curves. All other such punctured disc bundles are shown to be Kobayashi hyperbolic.

非Kähler超曲率变形及退化平衡流形的修改

Deformations of Non-Kähler Hyperbolicity Notions and Modifications of Degenerate Balanced Manifolds

本文提出两种新的非Kähler流形超曲率概念，并研究其在复变形下的行为及与其他超曲率概念的关系。

不变 2-喷射微分消失与二维情况下的改进双曲度数界

Vanishing of Invariant 2-Jet Differentials and Improved Hyperbolicity Degree Bounds in Dimension Two

本文提出二维Kobayashi双曲性度数界的新结果，证明了高次曲面和补集的双曲性，改进了传统界值，结合了代数简化与计算机代数技术。

Existence of close pseudoholomorphic disks for almost complex manifolds and an applications to Kobayashi-Royden pseudonorm

In this paper we extend the notion of the Kobayashi-Royden pseudonorm for almost complex manifolds. Its basic properties known from the complex analysis are preserved in the nonintegrable case as well. The main theorem on coincidence of the pseudodistance induced by this pseudonorm with the Kobayashi pseudodistance for the almost complex manifold is equivalent to the possibility of deforming slightly a pseudoholomorphic disk in an almost complex manifold. We also describe the result in terms of h-principle and consider a geometric application for moduli spaces of pseudoholomorphic curves.

Pseudoconvex regions of finite D'Angelo type in four dimensional almost complex manifolds

Let D be a J-pseudoconvex region in a smooth almost complex manifold (M,J) of real dimension four. We construct a local peak J-plurisubharmonic function at every boundary point p of finite D'Angelo type. As applications we give local estimates of the Kobayashi pseudometric, implying the local Kobayashi hyperbolicity of D at p. In case the point p is of D'Angelo type less than or equal to four, or the approach is nontangential, we provide sharp estimates of the Kobayashi pseudometric.

Hyperbolicity of general deformations: proofs

We modify the deformation method explored previously in a joint work of B. Shiffman and the author, in order to construct further examples of Kobayashi hyperbolic surfaces in the projective 3-space of any even degree starting with degree 8.

复流形中相对于Kobayashi距离的可见性域

Visibility domains relative to the Kobayashi distance in complex manifolds

本文将Kobayashi距离意义下的可见性推广到任意复流形中的域，在不假设Cauchy完备性的条件下给出多个充分条件，并由此建立一般框架下的Wolff--Denjoy型定理，同时探讨可见性与Gromov双曲性的联系。

Gromov hyperbolicity of strongly pseudoconvex almost complex manifolds

Let $D=\{ρ< 0\}$ be a smooth relatively compact domain in an almost complex manifold $(M,J)$, where $ρ$ is a smooth defining function of $D$, strictly $J$-plurisubharmonic in a neighborhood of the closure $\overline{D}$ of $D$. We prove that $D$ has a connected boundary and is Gromov hyperbolic.

Complex-analytic intermediate hyperbolicity, and finiteness properties

Motivated by the finiteness of the set of automorphisms Aut(X) of a projective manifold X, and by Kobayashi-Ochiai's conjecture that a projective manifold dim(X)-analytically hyperbolic (also known as strongly measure hyperbolic) should be of general type, we investigate the finiteness properties of Aut(X) for a complex manifold satisfying a (pseudo-) intermediate hyperbolicity property. We first show that a complex manifold X which is (dim(X) -- 1)-analytically hyperbolic has indeed finite automorphisms group. We then obtain a similar statement for a pseudo-(dim(X) -- 1)-analytically hyperbol…

Hyperbolicity of cycle spaces and automorphism groups of flag domains

If G_0 is a real form of a complex semisimple Lie group G and Z is compact G-homogeneous projective algebraic manifold, then G_0 has only finitely many orbits on Z. Complex analytic properties of open G_0-orbits D (flag domains) are studied. Schubert incidence-geometry is used to prove the Kobayashi hyperbolicity of certain cycle space components C_q(D). Using the hyperbolicity of C_q(D) and analyzing the action of Aut(D) on it, an exact description of Aut(D) is given. It is shown that, except in the easily understood case where D is holomorphically convex with a nontrivial Remmert reduction, …

Function theoretic properties of symmetric powers of complex manifolds

In the paper we study properties of symmetric powers of complex manifolds. We investigate a number of function theoretic properties (e. g. (quasi) $c$-finite compactness, existence of peak functions) that are preserved by taking the symmetric power. The case of symmetric products of planar domains is studied in a more detailed way. In particular, a complete description of the Carathéodory and Kobayashi hyperbolicity and Kobayashi completeness in that class of domains is presented.

双曲性性质的标记超kähler流形模空间

Hyperbolicity properties of moduli spaces of marked hyperk{ä}hler manifolds

研究标记超kähler流形模空间的双曲性性质，证明Kobayashi伪距离消失，并推广Greb和Schwald的定理到任意维数和非紧曲线情况。

Large Harnack inequalities, Kobayashi distances and holomorphic motions

We prove some generalizations and analogies of Harnack inequalities for pluriharmonic, holomorphic and "almost holomorphic" functions. The results are applied to the proving of smoothness properties of holomorphic motions over almost complex manifolds.

Hyperbolicity and Specialness of Symmetric Powers

Inspired by the computation of the Kodaira dimension of symmetric powers Xm of a complex projective variety X of dimension n $\ge$ 2 by Arapura and Archava, we study their analytic and algebraic hyperbolic properties. First we show that Xm is special if and only if X is special (except when the core of X is a curve). Then we construct dense entire curves in (suf-ficiently hig) symmetric powers of K3 surfaces and product of curves. We also give a criterion based on the positivity of jet differentials bundles that implies pseudo-hyperbolicity of symmetric powers. As an application, we obtain the…

关于超凯勒簇的反双曲性

On anti-hyperbolicity for hyperkähler varieties

本文研究超凯勒流形被同维数复仿射空间全纯或亚纯支配的反双曲性判据与例子，推广了 K3 曲面的相关已知结果。