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arXiv 2201.11033math.OA
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非豪斯多夫平展广群与左可消幺半群的C*-代数

Non-Hausdorff etale groupoids and C*-algebras of left cancellative monoids

University of Oslo(奥斯陆大学)

Sergey Neshveyev, Gaute Schwartz

AI总结:

该文研究局部紧平展广群单位空间稠子集表示确定约化范数的问题,给出充分条件与无挠迷向群情形的完整解答,提出左可消幺半群关联广群的C*-正则性概念并构造反例。

摘要:

我们研究了由局部紧平展广群单位空间的稠密子集定义的表示是否足以确定广群C*-代数上的约化范数这一问题。我们给出了两种结论各自的充分条件,在迷向群为无挠的情形下给出了完整解答。作为应用,我们考察了由Spielberg与左可消幺半群S关联的广群G(S),并提出了一个被我们称为C*-正则性的充分条件,可使典范映射C*_r(G(S))→C*_r(S)为同构,此时S具有良定义的完整半群C*-代数C*(S)=C*(G(S))。我们给出了左可消幺半群S和T两个相关例子:二者均非有限对齐,且关联的平展广群都是非豪斯多夫的,但S是C*-正则的,而T不是。

英文摘要:

We study the question whether the representations defined by a dense subset of the unit space of a locally compact étale groupoid are enough to determine the reduced norm on the groupoid C$^*$-algebra. We present sufficient conditions for either conclusion, giving a complete answer when the isotropy groups are torsion-free. As an application we consider the groupoid $G(S)$ associated to a left cancellative monoid $S$ by Spielberg and formulate a sufficient condition, which we call C$^*$-regularity, for the canonical map $C^*_r(G(S))\to C^*_r(S)$ to be an isomorphism, in which case $S$ has a well-defined full semigroup C$^*$-algebra $C^*(S)=C^*(G(S))$. We give two related examples of left cancellative monoids $S$ and $T$ such that both are not finitely aligned and have non-Hausdorff associated étale groupoids, but $S$ is C$^*$-regular, while $T$ is not.

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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