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arXiv 1503.00329math.RTmath.AC
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酉反射群的限制不变量

Restricting invariants of unitary reflection groups

Nils Amend, Angela Berardinelli, J. Matthew Douglass, Gerhard Roehrle

摘要:

设G是作用在复向量空间V上的有限酉反射群,X是G中某个元素的不动点子空间。定义N为X在G中的集态稳定子,Z为点态稳定子,C=N/Z。然后,限制定义了从V上的G-不变多项式函数代数到X上的C-不变函数代数的同态。推广了Douglass和Roehrle关于Coxeter群的工作,利用G和C的指数以及它们的反射排列刻画了任意酉反射群G的限制映射是满射的.我们主要结果的一个推论是X的G-饱和中G-轨道的多样性是光滑的当且仅当它是正规的。

英文摘要:

Suppose that G is a finite, unitary reflection group acting on a complex vector space V and X is the fixed point subspace of an element of G. Define N to be the setwise stabilizer of X in G, Z to be the pointwise stabilizer, and C=N/Z. Then restriction defines a homomorphism from the algebra of G-invariant polynomial functions on V to the algebra of C-invariant functions on X. Extending earlier work by Douglass and Roehrle for Coxeter groups, we characterize when the restriction mapping is surjective for arbitrary unitary reflection groups G in terms of the exponents of G and C, and their reflection arrangements. A consequence of our main result is that the variety of G-orbits in the G-saturation of X is smooth if and only if it is normal.

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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