Lie algebras

Orthogonal symmetric Lie algebra

In mathematics, an orthogonal symmetric Lie algebra is a pair consisting of a real Lie algebra and an automorphism of of order such that the eigenspace of s corresponding to 1 (i.e., the set of fixed points) is a compact subalgebra. If "compactness" is omitted, it is called a symmetric Lie algebra. An orthogonal symmetric Lie algebra is said to be effective if intersects the center of trivially. In practice, effectiveness is often assumed; we do this in this article as well. The canonical example is the Lie algebra of a symmetric space, being the differential of a symmetry. Let be effective orthogonal symmetric Lie algebra, and let denotes the -1 eigenspace of . We say that is of compact type if is compact and semisimple. If instead it is noncompact, semisimple, and if is a Cartan decomposition, then is of noncompact type. If is an Abelian ideal of , then is said to be of Euclidean type. Every effective, orthogonal symmetric Lie algebra decomposes into a direct sum of ideals , and , each invariant under and orthogonal with respect to the Killing form of , and such that if , and denote the restriction of to , and , respectively, then , and are effective orthogonal symmetric Lie algebras of Euclidean type, compact type and noncompact type. (Wikipedia).

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From playlist Linear Algebra

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From playlist Linear Algebra

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From playlist Algebra

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From playlist Linear Algebra

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From playlist Linear Algebra

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From playlist Linear Algebra

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From playlist Lie Groups and Lie Algebras

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Related pages

Direct sum | Semisimple Lie algebra | Compact Lie algebra | Trivial group | Mathematics | Symmetric space | Fixed point (mathematics) | Automorphism | Lie algebra | Killing form | Center (group theory)