Lie triple system T over a field F of characteristic zero. It turns out that it contains nontrivial elements if and only if T is related to a simple Jordan algebra. In particular this provides a new proof of the determination by Laquer of the invariant affine connections in the simply connected com
On Harmonic Elements for Semi-simple Lie Algebras
โ Scribed by Philippe Caldero
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 237 KB
- Volume
- 166
- Category
- Article
- ISSN
- 0001-8708
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โฆ Synopsis
Let g be a semi-simple complex Lie algebra and g=n -ร h ร n its triangular decomposition. Let U(g), resp. U q (g), be its enveloping algebra, resp. its quantized enveloping algebra. This article gives a quantum approach to the combinatorics of (classical) harmonic elements and Kostant's generalized exponents for g. A quantum analogue of the space of harmonic elements has been given by A. Joseph and G. Letzter (1994, Amer. J. Math. 116, 127-177). On the one hand, we give specialization results concerning harmonic elements, central elements of U q (g), and the decomposition of Joseph and Letzter (cited above). For g=sl n+1 , we describe the specialization of quantum harmonic space in the N-filtered algebra U(sl n+1 ) as the materialization of a theorem of A. Lascoux et al. (1995, Lett. Math. Phys. 35, 359-374). This enables us to study a Joseph-Letzter decomposition in the algebra U(sl n+1 ). On the other hand, we prove that highest weight harmonic elements can be calculated in terms of the dual of Lusztig's canonical basis. In the simply laced case, we parametrize a basis of n-invariants of minimal primitive quotients by the set C 0 of integral points of a convex cone.
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