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arXiv 1210.7625math.NTmath.AG
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剩余特征为2的二次格的群概型和局部密度

Group schemes and local densities of quadratic lattices in residue characteristic 2

Sungmun Cho

摘要:

著名的Smith-Minkowski-Siegel质量公式将二次晶格(L,Q)的质量表示为局部因子的乘积,称为(L,Q)的局部密度。这个质量公式是积分二次格分类的基本工具。在本文中,我们将通过构造一个合适的正交群的光滑积分群格式模型,明确地描述局部密度公式。我们的方法适用于Q_2的任何非分歧有限扩张。因此,我们给出了Conway和Sloane的局部密度公式的一个期待已久的证明,并发现了它对Q_2的非分歧有限扩张的推广。作为例子,我们给出了整二次型Q_n(x_1,.,x_n)=x_1^2 +. + x_n^2与一个数域k相关联,这个数域k是全实的并且使得理想(2)在k上是非分歧的。

英文摘要:

The celebrated Smith-Minkowski-Siegel mass formula expresses the mass of a quadratic lattice (L, Q) as a product of local factors, called the local densities of (L,Q). This mass formula is an essential tool for the classification of integral quadratic lattices. In this paper, we will describe the local density formula explicitly, by constructing a smooth integral group scheme model for an appropriate orthogonal group. Our method works for any unramified finite extension of Q_2. Therefore, we give a long awaited proof for the local density formula of Conway and Sloane and discover its generalization to unramified finite extensions of Q_2. As an example, we give the mass formula for the integral quadratic form Q_n(x_1, ..., x_n)=x_1^2 + ... + x_n^2 associated to a number field k which is totally real and such that the ideal (2) is unramified over k.

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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