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In algebraic number theory the ''n''-th power residue symbol (for an integer ''n'' > 2) is a generalization of the (quadratic) Legendre symbol to ''n''-th powers. These symbols are used in the statement and proof of cubic, quartic, Eisenstein, and related higher〔Quadratic reciprocity deals with squares; higher refers to cubes, fourth, and higher powers.〕 reciprocity laws.〔All the facts in this article are in Lemmermeyer Ch. 4.1 and Ireland & Rosen Ch. 14.2〕 ==Background and notation== Let ''k'' be an algebraic number field with ring of integers that contains a primitive ''n''-th root of unity Let be a prime ideal and assume that ''n'' and are coprime (i.e. .) The norm of is defined as the cardinality of the residue class ring (since is prime this is a finite field) There is an analogue of Fermat's theorem in If then : And finally, These facts imply that : is well-defined and congruent to a unique ''n''-th root of unity ζ''n''''s''. 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「power residue symbol」の詳細全文を読む スポンサード リンク
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