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In mathematics, the complex Witt algebra, named after Ernst Witt, is the Lie algebra of meromorphic vector fields defined on the Riemann sphere that are holomorphic except at two fixed points. It is also the complexification of the Lie algebra of polynomial vector fields on a circle, and the Lie algebra of derivations of the ring C(). Witt algebras occur in the study of conformal field theory. There are some related Lie algebras defined over finite fields, that are also called Witt algebras. The complex Witt algebra was first defined by Cartan (1909), and its analogues over finite fields were studied by Witt in the 1930s. ==Basis== A basis for the Witt algebra is given by the vector fields , for ''n'' in ''''. The Lie bracket of two vector fields is given by : This algebra has a central extension called the Virasoro algebra that is important in conformal field theory and string theory. Note that by restricting ''n'' to 1,0,-1, one gets a subalgebra. Taken over the field of complex numbers, this is just the algebra of the Lorentz group SL(2,C). Over the reals, it is the algrebra sl(2,R) = su(1,1). 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「Witt algebra」の詳細全文を読む スポンサード リンク
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