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arXiv 1304.7482math.DG
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仿射投射Osserman结构

Affine projective Osserman structures

Peter Gilkey, Stana Nikcevic

摘要:

通过考虑Jacobi算子的投影谱,我们在仿射和伪黎曼背景下引入了投影Osserman流形的概念。若M是仿射投射Osserman流形,则余切丛上的修正黎曼扩张度量既是类空投射Osserman,又是类时投射Osserman。由于任何秩为1的对称空间都是仿射投射Osserman,这提供了关于秩为1的黎曼对称空间的余切丛与修改的黎曼扩张度量的额外信息。我们构造仿射投影Osserman流形的其他例子,其中Ricci张量不是对称的,因此连接不是任何度量的Levi-Civita连接。若M是奇数维仿射射影Osserman流形,我们利用代数拓扑的方法证明了Jacobi算子只有一个非零特征值,且该特征值是实的。

英文摘要:

By considering the projectivized spectrum of the Jacobi operator, we introduce the concept of projective Osserman manifold in both the affine and in the pseudo-Riemannian settings. If M is an affine projective Osserman manifold, then the modified Riemannian extension metric on the cotangent bundle is both spacelike and timelike projective Osserman. Since any rank 1 symmetric space is affine projective Osserman, this provides additional information concerning the cotangent bundle of a rank 1 Riemannian symmetric space with the modified Riemannian extension metric. We construct other examples of affine projective Osserman manifolds where the Ricci tensor is not symmetric and thus the connection is not the Levi-Civita connection of any metric. If M is an affine projective Osserman manifold of odd dimension, we use methods of algebraic topology to show the Jacobi operator has only one non-zero eigenvalue and that eigenvalue is real.

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