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arXiv math/0012091math.OA
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正合群、诱导理想和Fell丛

Exact Groups, Induced Ideals, and Fell Bundles

Ruy Exel

摘要:

给定离散群G上分次的C* 代数-代数B,我们考虑B的理想在每个分次子空间上的投影下是不变的.如果G是精确的,B的标准条件期望是忠实的,我们证明了所有这样的理想都是诱导的,即是由它们与单位纤维代数的交集生成的。这个结果是由Kirchberg和Wasserman的一个定理推广到Fell丛的上下文中得到的,根据这个定理,一个群是正合的当且仅当它的约化C* 代数是正合的。

英文摘要:

Given a C*-algebra B which is graded over a discrete group G we consider ideals of B which are invariant under the projections onto each of the grading subspaces. If G is exact and the standard conditional expectation of B is faithful we show that all such ideals are induced, i.e. are generated by their intersection with the unit fiber algebra. This result is derived from a generalization to the context of Fell bundles of a Theorem by Kirchberg and Wasserman according to which a group is exact if and only if its reduced C*-algebra is exact.

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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