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regular local ring (Definition)

A local ring $ R$ of dimension $ n$ is regular if and only if its maximal ideal $ \mathfrak{m}$ is generated by $ n$ elements.

Equivalently, $ R$ is regular if $ \dim_{R/\mathfrak{m}}\mathfrak{m}/\mathfrak{m}^2=\dim R$, where the first dimension is that of a vector space, and the latter is the Krull dimension, since by Nakayama's lemma, elements generate $ \mathfrak{m}$ if and only if their images under the projection generate $ \mathfrak{m}/\mathfrak{m}^2$.

By Krull's principal ideal theorem, $ \mathfrak{m}$ cannot be generated by fewer than $ n$ elements, so the maximal ideals of regular local rings have a minimal number of generators.



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"regular local ring" is owned by mps. [ full author list (2) | owner history (1) ]
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Cross-references: generators, minimal number, Krull's principal ideal theorem, projection, images, generate, Nakayama's lemma, Krull dimension, vector space, generated by, maximal ideal, local ring
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This is version 3 of regular local ring, born on 2002-12-27, modified 2004-04-23.
Object id is 3851, canonical name is RegularLocalRing.
Accessed 2846 times total.

Classification:
AMS MSC13H05 (Commutative rings and algebras :: Local rings and semilocal rings :: Regular local rings)

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