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In abstract algebra, a congruence relation (or simply congruence) is an equivalence relation on an algebraic structure (such as a group, ring, or vector space) that is compatible with the structure. Every congruence relation has a corresponding quotient structure, whose elements are the equivalence classes (or congruence classes) for the relation. ==Basic example== The prototypical example of a congruence relation is congruence modulo on the set of integers. For a given positive integer , two integers and are called congruent modulo , written : if is divisible by (or equivalently if and have the same remainder when divided by ). for example, and are congruent modulo , : since is a multiple of 10, or equivalently since both and have a remainder of when divided by . Congruence modulo (for a fixed ) is compatible with both addition and multiplication on the integers. That is, if : and then : and The corresponding addition and multiplication of equivalence classes is known as modular arithmetic. From the point of view of abstract algebra, congruence modulo is a congruence relation on the ring of integers, and arithmetic modulo occurs on the corresponding quotient ring. 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「Congruence relation」の詳細全文を読む スポンサード リンク
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