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arXiv 1111.1449math.DSmath.GRmath.GT
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关于同胚群的偏差

On distortion in groups of homeomorphisms

Światosław Gal, Jarek Kędra

摘要:

设X是允许泛覆盖的路连通拓扑空间。设Homeo(X,a)表示X的保一次上同调类a的同胚群.我们研究了Homeo(X,a)中的畸变。设g是Homeo(X,a)中的一个元素.本文在X上g-不变Borel概率测度空间上定义了一个Nielsen型等价关系,并证明了如果同胚g允许两个不等价的不变测度,则它是不失真的.我们还定义了一个局部的同胚的旋转数推广的概念旋转同胚的圆。然后证明了如果同胚的旋转数是非常数,则它是无畸变的。

英文摘要:

Let X be a path-connected topological space admitting a universal cover. Let Homeo(X,a) denote the group of homeomorphisms of X preserving degree one cohomology class a. We investigate the distortion in Homeo(X,a). Let g be an element of Homeo(X,a). We define a Nielsen-type equivalence relation on the space of g-invariant Borel probability measures on X and prove that if a homeomorphism g admits two nonequivalent invariant measures then it is undistorted. We also define a local rotation number of a homeomorphism generalising the notion of the rotation of a homeomorphism of the circle. Then we prove that a homeomorphism is undistorted if its rotation number is nonconstant.

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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