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arXiv 1702.02649math.AG
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关于$G_2$分类栈的动机类与自旋群

On the motivic class of the classifying stack of $G_2$ and the spin groups

Roberto Pirisi, Mattia Talpo

摘要:

本文计算了例外代数群$G_2$和自旋群$\mathrm{Spin}_7$和$\mathrm{Spin}_8$在Grothendieck栈环中的分类栈的类,并证明了它们与相应群的类的逆相等.此外,我们表明,栈$\mathscr{B}\mathrm{Spin}_n$的motivic类的计算可以减少到$\mathscr{B} Δ_n$的类的计算,其中$Δ_n\subset \mathrm{Pin}_n$是“extraspecial $2$ -组”,下的投影$\mathrm{Pin}_n\to \mathrm{O}_n$正交组的对角矩阵的原像。

英文摘要:

We compute the class of the classifying stack of the exceptional algebraic group $G_2$ and of the spin groups $\mathrm{Spin}_7$ and $\mathrm{Spin}_8$ in the Grothendieck ring of stacks, and show that they are equal to the inverse of the class of the corresponding group. Furthermore, we show that the computation of the motivic classes of the stacks $\mathscr{B}\mathrm{Spin}_n$ can be reduced to the computation of the classes of $\mathscr{B} Δ_n$, where $Δ_n\subset \mathrm{Pin}_n$ is the "extraspecial $2$-group", the preimage of the diagonal matrices under the projection $\mathrm{Pin}_n\to \mathrm{O}_n$ to the orthogonal group.

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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