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arXiv 0705.2390math.DGmath.AP
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抛物几何的广义Einstein条件和锥构造

Generalised Einstein condition and cone construction for parabolic geometries

Stuart Armstrong

摘要:

本文试图定义一个推广的标准爱因斯坦条件(共形/度量几何)的任何抛物几何。为了做到这一点,它表明,任何保留的对合$σ$的伴随丛$\mc{A}$引起,给定一定的代数条件下,一个唯一的首选仿射联络$\nabla$与协变常数ρ张量$\mathsf{P}$,兼容的代数括号$\mc{A}$。这些条件可以合理地认为是爱因斯坦条件的推广,并在共形几何中重新建立了标准的爱因斯坦条件。这样一个对合的存在是由一些简单的结构所暗示的:当整个代数$\mf{g}$是$\mf{sl}(m,\mbb{F})$时保持度量,对于$\mf{g}=\mf{sp}(2m,\mbb{F})$保持与斜形式反交换的复结构,以及对于所有其他非例外单李代数保持切丛的一定秩的子。爱因斯坦对合的例子构造或引用几个几何。然后证明了某些爱因斯坦对合的锥结构的存在性。

英文摘要:

This paper attempts to define a generalisation of the standard Einstein condition (in conformal/metric geometry) to any parabolic geometry. To do so, it shows that any preserved involution $σ$ of the adjoint bundle $\mc{A}$ gives rise, given certain algebraic conditions, to a unique preferred affine connection $\nabla$ with covariantly constant rho-tensor $\mathsf{P}$, compatible with the algebraic bracket on $\mc{A}$. These conditions can reasonably be considered the generalisations of the Einstein condition, and recreate the standard Einstein condition in conformal geometry. The existence of such an involution is implies by some simpler structures: preserved metrics when the overall algebra $\mf{g}$ is $\mf{sl}(m,\mbb{F})$, preserved complex structures anti-commuting with the skew-form for $\mf{g}=\mf{sp}(2m,\mbb{F})$, and preserved subundles of the tangent bundle, of a certain rank, for all the other non-exceptional simple Lie algebras. Examples of Einstein involutions are constructed or referenced for several geometries. The existence of cone constructions for certain Einstein involutions is then demonstrated.

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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