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arXiv 0904.2636math.DG
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平行子流形的外禀齐性

Extrinsic homogeneity of parallel submanifolds

Tillmann Jentsch

摘要:

考虑黎曼对称空间$N$的平行子流形$M$,研究了$M$在$N$中是否是超齐次的问题,即是否存在$N$的等距群的子群传递地作用于$M$ \,.首先,给定一个在某点$p\in N$上的“2-jet”$(W,b)$(即$W\subset T_pN$是线性空间,$b:W\times W\to W^\bot$是对称双线性型),,得到了一个具有外齐次切完整丛的平行子流形存在的充要条件,该子流形通过$p$,并且其在$p$上的2-jet由$(W,b)$,给出.其次,我们把注意力集中在\em\,.设$N$为紧型或非紧型,我们建立了$N$的维数至少为3且不包含在$N$的任何平坦空间中的完备不可约平行子流形的外齐性.

英文摘要:

We consider parallel submanifolds $M$ of a Riemannian symmetric space $N$ and study the question whether $M$ is extrinsically homogeneous in $N$\,, i.e.\ whether there exists a subgroup of the isometry group of $N$ which acts transitively on $M$\,. First, given a "2-jet" $(W,b)$ at some point $p\in N$ (i.e. $W\subset T_pN$ is a linear space and $b:W\times W\to W^\bot$ is a symmetric bilinear form)\,, we derive necessary and sufficient conditions for the existence of a parallel submanifold with extrinsically homogeneous tangent holonomy bundle which passes through $p$ and whose 2-jet at $p$ is given by $(W,b)$\,. Second, we focus our attention on complete, (intrinsically) {\em irreducible} parallel submanifolds of $N$\,. Provided that $N$ is of compact or non-compact type, we establish the extrinsic homogeneity of every complete, irreducible parallel submanifold of $N$ whose dimension is at least 3 and which is not contained in any flat of $N$\,.

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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