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arXiv 1012.4135math.DGmath.GT
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切球面丛的同伦性与拓扑

Homotheties and topology of tangent sphere bundles

Rui Albuquerque

摘要:

本文证明了一个关于$\dim\geq 3$的黎曼流形$M,g$的两个给定切球面丛$S_rM$之间的同素性定理,假定$g$的共形类诱导了不同的变半径函数$r$和加权Sasaki度量.新的例子表明,流形与常数正或常数负标量曲率,这不是爱因斯坦。回顾有关流形$TM$上的殆复结构$I^G$和辛结构$ω^G$的结果,通过承认权和挠的连接推广了著名的Sasaki结构,我们计算了流形$TM$和$S_rM$的Chern和Stiefel-Whitney特征类.

英文摘要:

We prove a Theorem on homotheties between two given tangent sphere bundles $S_rM$ of a Riemannian manifold $M,g$ of $\dim\geq 3$, assuming different variable radius functions $r$ and weighted Sasaki metrics induced by the conformal class of $g$. New examples are shown of manifolds with constant positive or with constant negative scalar curvature, which are not Einstein. Recalling results on the associated almost complex structure $I^G$ and symplectic structure $ω^G$ on the manifold $TM$, generalizing the well-known structure of Sasaki by admitting weights and connections with torsion, we compute the Chern and the Stiefel-Whitney characteristic classes of the manifolds $TM$ and $S_rM$.

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