Localization (commutative algebra): Difference between revisions

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EureKB (talk | contribs)
clarified ambiguity in the definition
EmlynXF (talk | contribs)
m Minor edit but crucial. The direct sum is a colimit while the product is a limit, and tensors commute with colimits, not limits. Because of this, the product of flat modules is not necessarily flat, while the sum is. Localization at primes
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Many local properties are a consequence of the fact that the ring
:<math>\prod_bigoplus_\mathfrak p R_\mathfrak p</math>
is a [[faithfully flat module]] when the productdirect sum is taken over all prime ideals (or over all [[maximal ideal]]s of {{mvar|R}}). See also [[Faithfully flat descent]].
 
=== Examples of local properties ===