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Wheels are a type of algebra where division is always defined. In particular, division by zero is meaningful. The real numbers can be extended to a wheel, as can any commutative ring. Also the Riemann sphere can be extended to a wheel by adjoining an element . The Riemann sphere is an extension of the complex plane by an element , where for any complex . However, is still undefined on the Riemann sphere, but defined in wheels. == The algebra of wheels == Wheels discard the usual notion of division being a binary operator, replacing it with multiplication by a unary operator similar (but not identical) to the multiplicative inverse , such that becomes shorthand for , and modifies the rules of algebra such that * in the general case. * in the general case. * in the general case, as is not the same as the multiplicative inverse of . Precisely, a wheel is an algebraic structure with operations binary addition , multiplication , constants 0, 1 and unary , satisfying: * Addition and multiplication are commutative and associative, with 0 and 1 as their respective identities. * and * * * * * * If there is an element with , then we may define negation by and . Other identities that may be derived are * * * However, if and we get the usual * * The subset is always a commutative ring if negation can be defined as above, and every commutative ring is such a subset of a wheel. If is an invertible element of the commutative ring, then . Thus, whenever makes sense, it is equal to , but the latter is always defined, even when . 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「Wheel theory」の詳細全文を読む スポンサード リンク
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