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arXiv 1502.02755math.DG
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Sp(2)/U(1)与一个正曲率问题

Sp(2)/U(1) and a Positive Curvature Problem

Ming Xu, Joseph A. Wolf

摘要:

一个具有双不变正交分解$\mathfrak{g}=\mathfrak{h}+\mathfrak{m}$的紧致黎曼齐性空间$G/H$称为交换对正弯曲的,如果对于$\mathfrak{m}$中线性无关交换对所张成的$T_{eH}(G/H)$中的任意切面,截面曲率为零.本文证明了在陪集空间$\mathrm{Sp}(2)/\mathrm{U}(1)$上,$\mathrm{U}(1)$对应于一个短根,交换对允许正曲度量. B. Wilking最近证明了这个$\mathrm{Sp}(2)/\mathrm{U}(1)$不可能是一般意义上的正弯曲。这是第一个例子,以区分一组紧凑的陪集空间承认正弯曲的度量,和度量正弯曲的交换对。

英文摘要:

A compact Riemannian homogeneous space $G/H$, with a bi--invariant orthogonal decomposition $\mathfrak{g}=\mathfrak{h}+\mathfrak{m}$ is called positively curved for commuting pairs, if the sectional curvature vanishes for any tangent plane in $T_{eH}(G/H)$ spanned by a linearly independent commuting pair in $\mathfrak{m}$. In this paper,we will prove that on the coset space $\mathrm{Sp}(2)/\mathrm{U}(1)$, in which $\mathrm{U}(1)$ corresponds to a short root, admits positively curved metrics for commuting pairs. B. Wilking recently proved that this $\mathrm{Sp}(2)/\mathrm{U}(1)$ can not be positively curved in the general sense. This is the first example to distinguish the set of compact coset spaces admitting positively curved metrics, and that for metrics positively curved only for commuting pairs.

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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