按照数学家们的分类，三叶形是最简单的纽结。 所谓纽结，它是三维空间中不与自己相交的封闭曲线，或者说是三维空间中与圆周同胚的图形。

The trefoil is the simplest knot in mathematicians' classification.

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然后，我们将看到微分同胚群作用下的辛商为特殊子流形模空间上的以环面为结构群的丛。

And then we will see that in the framework of diffeomorphism group the symplectic quotient is torus bundle over the moduli space of special submanifold.

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本文给出了度量空间中某些同胚非扩张映射不动点存在的充分必要条件。

In this paper, some results on fixed points of homeomorphic maps in metric Spaces have been obtained.

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