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Semi-local ring
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== Examples == * Any right or left [[Artinian ring]], any [[serial ring]], and any [[semiperfect ring]] is semi-local. * The quotient <math>\mathbb{Z}/m\mathbb{Z}</math> is a semi-local ring. In particular, if <math>m</math> is a prime power, then <math>\mathbb{Z}/m\mathbb{Z}</math> is a local ring. * A finite direct sum of fields <math>\bigoplus_{i=1}^n{F_i}</math> is a semi-local ring. * In the case of commutative rings with unity, this example is prototypical in the following sense: the [[Chinese remainder theorem]] shows that for a semi-local commutative ring ''R'' with unit and maximal ideals ''m''<sub>1</sub>, ..., ''m<sub>n</sub>'' :<math>R/\bigcap_{i=1}^n m_i\cong\bigoplus_{i=1}^n R/m_i\,</math>. :(The map is the natural projection). The right hand side is a direct sum of fields. Here we note that β©<sub>i</sub> m<sub>i</sub>=J(''R''), and we see that ''R''/J(''R'') is indeed a semisimple ring. * The [[classical ring of quotients]] for any commutative Noetherian ring is a semilocal ring. * The [[endomorphism ring]] of an [[Artinian module]] is a semilocal ring. * Semi-local rings occur for example in [[algebraic geometry]] when a (commutative) ring ''R'' is [[Localization of a ring|localized]] with respect to the [[multiplicatively closed]] subset ''S = β© (R \ p<sub>i</sub>)'', where the ''p<sub>i</sub>'' are finitely many [[prime ideal]]s.
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