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arXiv math/9808008math.SG
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$S^2\times S^2$上的殆复结构

Almost Complex Structures on $S^2\times S^2$

Dusa McDuff

摘要:

本文研究了$S^2\times S^2$上光滑殆复结构的空间$\Jj$的结构,这些结构与某些辛形式相容。这个空间有一个自然的分层,随着形式的上同调类的变化而变化,其性质与$S^2\times S^2$的辛同胚群的拓扑关系非常密切。通过对稳定映射理论中的标准胶合构造进行整体化,我们证明了$\Jj$的层是有限余维的Fréchet流形,并且每层的法链是有限维的分层空间.这些链接的拓扑结构是令人惊讶的复杂,我们解决了某些情况。我们的论证也适用于其他直纹曲面,尽管它们只对$S^2$和$T^2$上的丛给出了完整的信息。

英文摘要:

In this note we investigate the structure of the space $\Jj$ of smooth almost complex structures on $S^2\times S^2$ that are compatible with some symplectic form. This space has a natural stratification that changes as the cohomology class of the form changes and whose properties are very closely connected to the topology of the group of symplectomorphisms of $S^2\times S^2$. By globalizing standard gluing constructions in the theory of stable maps, we show that the strata of $\Jj$ are Fréchet manifolds of finite codimension, and that the normal link of each stratum is a finite dimensional stratified space. The topology of these links turns out to be surprisingly intricate, and we work out certain cases. Our arguments apply also to other ruled surfaces, though they give complete information only for bundles over $S^2$ and $T^2$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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