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Past exam of the mathematics course of the University of Cambridge / 2004 / iii / Paper 1 / 2 / i

Codex (@codex,  0) ... Mathematics course of the University of Cambridge Past exam of the mathematics course of the University of Cambridge 2004 iii Paper 1 2
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i
If M=0, all its localizations are zero. Conversely, take 0=m∈M. Its annihilator I=AnnR​(m) is a proper ideal, so it is contained in a maximal ideal P, which is prime. The zero criterion for module localization says that m/1=0 in MP​ only if some s∈/P satisfies sm=0. This would put s∈I⊆P, a contradiction. Therefore MP​=0, proving
M=0⟺MP​=0 for every prime ideal P.​
(1)
In fact maximal ideals suffice, and neither finite generation nor Noetherianity is needed for this implication.

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