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In a field of mathematics known as differential geometry, a Courant algebroid is a structure which, in a certain sense, blends the concepts of Lie algebroid and of quadratic Lie algebra. This notion, which plays a fundamental role in the study of Hitchin's generalized complex structures, was originally introduced by Zhang-Ju Liu, Alan Weinstein and Ping Xu in their investigation of doubles of Lie bialgebroids in 1997.〔Z-J. Liu, A. Weinstein, and P. Xu: ( Manin triples for Lie Bialgebroids ), Journ. of Diff.geom. 45 pp.647–574 (1997).〕 Liu, Weinstein and Xu named it after Courant, who had implicitly devised earlier in 1990〔T.J. Courant: ''Dirac Manifolds'', Transactions of the AMS, vol. 319, pp.631–661 (1990).〕 the standard prototype of Courant algebroid through his discovery of a skew symmetric bracket on , called Courant bracket today, which fails to satisfy the Jacobi identity. Both this standard example and the double of a Lie bialgebra are special instances of Courant algebroids. ==Definition== A Courant algebroid consists of the data a vector bundle with a bracket , a non degenerate fiber-wise inner product , and a bundle map subject to the following axioms, : : : where ''φ,ψ,χ'' are sections of ''E'' and ''f'' is a smooth function on the base manifold ''M''. ''D'' is the combination with ''d'' the de Rham differential, the dual map of , and ''κ'' the map from ''E'' to induced by the inner product. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Courant algebroid」の詳細全文を読む スポンサード リンク
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