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In abstract algebra, the term associator is used in different ways as a measure of the nonassociativity of an algebraic structure. ==Ring theory== For a nonassociative ring or algebra , the associator is the multilinear map given by : Just as the commutator measures the degree of noncommutativity, the associator measures the degree of nonassociativity of . It is identically zero for an associative ring or algebra. The associator in any ring obeys the identity : The associator is alternating precisely when is an alternative ring. The associator is symmetric in its two rightmost arguments when is a pre-Lie algebra. The nucleus is the set of elements that associate with all others: that is, the ''n'' in ''R'' such that : It turns out that any two of being implies that the third is also the zero set. 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「associator」の詳細全文を読む スポンサード リンク
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