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In representation theory, a branch of mathematics, the Kostant partition function, introduced by , of a root system is the number of ways one can represent a vector (weight) as an integral non-negative sum of the positive roots . Kostant used it to rewrite the Weyl character formula for the multiplicity of a weight of an irreducible representation of a semisimple Lie algebra. The Kostant partition function can also be defined for Kac–Moody algebras and has similar properties. ==Relation to the Weyl character formula== The values of Kostant's partition function are given by the coefficients of the power series expansion of : where the product is over all positive roots. Using Weyl's denominator formula : shows that the Weyl character formula : can also be written as : This allows the multiplicities of finite-dimensional irreducible representations in Weyl's character formula to be written as a finite sum involving values of the Kostant partition function, as these are the coefficients of the power series expansion of the denominator of the right hand side. 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「Kostant partition function」の詳細全文を読む スポンサード リンク
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