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arXiv math/0110051math.AGmath.CV
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特殊品种与分类理论

Special Varieties and classification Theory

Frederic Campana

摘要:

定义了一类新的紧致Kähler流形,称之为特殊Kähler流形,它是指不具有到一般型轨道的满射亚纯映射的紧致Kähler流形。特殊流形在许多方面是有理曲线和椭圆曲线的高维推广。例如,我们表明,合理连接或具有消失Kodaira维度意味着是特殊的。此外,对于任何紧致Kähler $X$,我们定义一个纤维化$c_X:X\to C(X)$,我们称之为它的核,使得$c_X$的一般纤维是特殊的,并且包含$X$的一般点的$X$的每个特殊子簇包含在$c_X$的相应纤维中。在低维和某些情形下,我们猜想并证明了:1)特殊流形有几乎交换的基本群。2)特殊流形就是Kobayashi伪度量为零的流形。3)核心是一般类型的纤维化,这意味着当配备有来自$c_X$的多个纤维的轨道折叠结构时,其基础$C(X)$也是如此。4)通过对$C(X)$上的轨道折叠Kobayashi伪度量的拉回,得到了$X$的Kobayashi伪度量. 5)如果$X$是射影的,定义在复数域的某个非线性生成的(在$\Bbb Q$上)子域$K$上,则$X$的$K$ -有理点的集合由核映射到$C(X)$的真代数子集中。当$X$是一般类型时,这最后两个公式是对Lang公式的任意$X$的自然推广。

英文摘要:

A new class of compact Kähler manifolds, called special, is defined, which are the ones having no surjective meromorphic map to an orbifold of general type. The special manifolds are in many respect higher-dimensional generalisations of rational and elliptic curves. For example, we show that being rationally connected or having vanishing Kodaira dimension implies being special. Moreover, for any compact Kähler $X$ we define a fibration $c_X:X\to C(X)$, which we call its core, such that the general fibres of $c_X$ are special, and every special subvariety of $X$ containing a general point of $X$ is contained in the corresponding fibre of $c_X$. We then conjecture and prove in low dimensions and some cases that: 1) Special manifolds have an almost abelian fundamental group. 2) Special manifolds are exactly the ones having a vanishing Kobayashi pseudometric. 3) The core is a fibration of general type, which means that so is its base $C(X)$,when equipped with its orbifold structure coming from the multiple fibres of $c_X$. 4) The Kobayashi pseudometric of $X$ is obtained as the pull-back of the orbifold Kobayashi pseudo-metric on $C(X)$, which is a metric outside some proper algebraic subset. 5) If $X$ is projective,defined over some finitely generated (over $\Bbb Q$) subfield $K$ of the complex number field, the set of $K$-rational points of $X$ is mapped by the core into a proper algebraic subset of $C(X)$. These two last conjectures are the natural generalisations to arbitrary $X$ of Lang's conjectures formulated when $X$ is of general type.

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