Bourbaki

Corollary

Tag 04AC, permanent. Cite it as [Bourbaki, Tag 04AC].

Commutative Algebra, chapter II, § 4. Spectra of rings and supports of modules

Let AA be a ring, MM an AA-module, (mi)i∈I(m_i)_{i \in I} a system of generators of MM and aa, the annihilator of mim_i. Then

Supp⁡(M)=⋃i∈IV(ai). \operatorname{Supp}(M) = \bigcup_{i \in I} V(a_i).
Supp⁡(M)=⋃i∈ISupp⁡(Ami)\operatorname{Supp}(M) = \bigcup_{i \in I} \operatorname{Supp}(Am_i) by Proposition 16 (ii). On the other hand, AmiAm_i is isomorphic to the AA-module A/aiA/a_i and we have seen that
Supp⁡(A/ai)=V(ai) \operatorname{Supp}(A/a_i) = V(a_i)
(Example above).

Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.

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Transcribed from the printed volume. Not translated.