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arXiv 0908.0685math.GTmath.GR
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映射类群在CAT(0)空间上的半单作用

Semisimple actions of mapping class groups on CAT(0) spaces

Martin R Bridson

摘要:

设S是有限型可定向曲面,Mod(S)是它的映射类群.本文考虑完备CAT(0)空间上Mod(S)的半单等距作用。如果S的亏格至少为3,则在任何这样的作用中,所有的德恩扭转都充当椭圆等距。Mod(S)在具有Weil-Petersson度量的Teichmüller空间的完备化上的作用表明存在这种有趣的作用。当亏格为g的闭可定向曲面的映射类群通过半单等距作用在维数小于g的完备CAT(0)空间上时,必不动点.亏格为2的闭曲面的映射类群在18维完备CAT(0)空间上通过半单等距作用。

英文摘要:

Let S be an orientable surface of finite type and let Mod(S) be its mapping class group. We consider actions of Mod(S) by semisimple isometries on complete CAT(0) spaces. If the genus of S is at least 3, then in any such action all Dehn twists act as elliptic isometries. The action of Mod(S) on the completion of Teichmüller space with the Weil-Petersson metric shows that there are interesting actions of this type. Whenever the mapping class group of a closed orientable surface of genus g acts by semisimple isometries on a complete CAT(0) space of dimension less than g it must fix a point. The mapping class group of a closed surface of genus 2 acts properly by semisimple isometries on a complete CAT(0) space of dimension 18.

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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