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arXiv 1902.08396math.DG
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Damek-Ricci空间的全测地子流形与Cayley射影平面的Einstein超曲面

Totally geodesic submanifolds of Damek-Ricci spaces and Einstein hypersurfaces of the Cayley projective plane

Sinhwi Kim, Yuri Nikolayevsky, JeongHyeong Park

摘要:

我们对Damek-Ricci空间的全测地子流形进行了分类,并证明了它们要么是齐性的(这样的子流形被认为是“较小的”Damek-Ricci空间),要么等距于负曲率的秩1对称空间.作为副产品,我们得到了任何已知调和流形的全测地子流形本身是调和的。我们证明了Cayley双曲平面上不存在Einstein超曲面,并且Cayley射影平面上唯一的Einstein超曲面是具有特定半径的测地球面,从而完成了秩一对称空间中Einstein超曲面的分类.我们还证明了,如果一个$2$ -stein空间允许一个$2$ -stein超曲面,那么在某些附加条件下,这两个超曲面都是常曲率的.

英文摘要:

We classify totally geodesic submanifolds of Damek-Ricci spaces and show that they are either homogeneous (such submanifolds are known to be "smaller" Damek-Ricci spaces) or isometric to rank-one symmetric spaces of negative curvature. As a by-product, we obtain that a totally geodesic submanifold of any known harmonic manifold is by itself harmonic. We prove that the Cayley hyperbolic plane admits no Einstein hypersurfaces and that the only Einstein hypersurfaces in the Cayley projective plane are geodesic spheres of a particular radius; this completes the classification of Einstein hypersurfaces in rank-one symmetric spaces. We also show that if a $2$-stein space admits a $2$-stein hypersurface, then both are of constant curvature, under some additional conditions.

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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