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In algebraic geometry, the motivic zeta function of a smooth algebraic variety is the formal power series : Here is the -th symmetric power of , i.e., the quotient of by the action of the symmetric group , and is the class of in the ring of motives (see below). If the ground field is finite, and one applies the counting measure to , one obtains the local zeta function of . If the ground field is the complex numbers, and one applies Euler characteristic with compact supports to , one obtains . == Motivic measures == A motivic measure is a map from the set of finite type schemes over a field to a commutative ring , satisfying the three properties : depends only on the isomorphism class of , : if is a closed subscheme of , :. For example if is a finite field and is the ring of integers, then defines a motivic measure, the ''counting measure''. If the ground field is the complex numbers, then Euler characteristic with compact supports defines a motivic measure with values in the integers. The zeta function with respect to a motivic measure is the formal power series in given by :. There is a ''universal motivic measure''. It takes values in the K-ring of varieties, , which is the ring generated by the symbols , for all varieties , subject to the relations : if and are isomorphic, : if is a closed subvariety of , :. The universal motivic measure gives rise to the motivic zeta function. 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「Motivic zeta function」の詳細全文を読む スポンサード リンク
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