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arXiv 0809.2130math.DGmath.SG
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可微堆栈的体积

The volume of a differentiable stack

Alan Weinstein

摘要:

我们将离散群胚的基数概念(等于相应离散轨道的欧拉示性数)推广到李群胚的情形。由于这个量在群胚等价下是不变量,我们称它为相关栈的体积,而不是群胚本身的体积。由于在光滑情况下没有像离散情况下的计数测度那样的自然测度,我们需要额外的数据来定义体积。该数据具有广群上自然线丛的不变截面的形式。这个线丛的平方根的部分构成堆栈的“固有希尔伯特空间“。

英文摘要:

We extend the notion of the cardinality of a discrete groupoid (equal to the Euler characteristic of the corresponding discrete orbifold) to the setting of Lie groupoids. Since this quantity is an invariant under equivalence of groupoids, we call it the volume of the associated stack rather than of the groupoid itself. Since there is no natural measure in the smooth case like the counting measure in the discrete case, we need extra data to define the volume. This data has the form of an invariant section of a natural line bundle over the groupoid. Sections of a square root of this line bundle constitute an "intrinsic Hilbert space" of the stack.

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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