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arXiv 1111.7214math.RAmath.DS
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阿贝尔群的斜群环的单性

Simplicity of skew group rings of abelian groups

Johan Öinert

摘要:

给定一个群G,一个(酉)环A和一个群同态$σ: G \to \Aut(A)$,可以构造斜群环$A \rtimes_σ G$。证明了阿贝尔群G的斜群环$A \rtimes_σ G$是单的当且仅当它的中心是域且A是G-单的.若G是交换的,A是交换的,则$A \rtimes_σ G$是单的当且仅当σ是内射的,A是G-单的.作为应用,我们证明了变换群(X,G)是极小的且忠实的当且仅当它的斜群代数$C(X) \rtimes_σ G$是单的,其中X是紧Hausdorff空间,G是交换的.我们还提供了一个例子,斜群代数,(非阿贝尔)ICC群,其中上述结论不成立。

英文摘要:

Given a group G, a (unital) ring A and a group homomorphism $σ: G \to \Aut(A)$, one can construct the skew group ring $A \rtimes_σ G$. We show that a skew group ring $A \rtimes_σ G$, of an abelian group G, is simple if and only if its centre is a field and A is G-simple. If G is abelian and A is commutative, then $A \rtimes_σ G$ is shown to be simple if and only if σis injective and A is G-simple. As an application we show that a transformation group (X,G), where X is a compact Hausdorff space and G is abelian, is minimal and faithful if and only if its associated skew group algebra $C(X) \rtimes_σ G$ is simple. We also provide an example of a skew group algebra, of an (non-abelian) ICC group, for which the above conclusions fail to hold.

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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