Bourbaki

Proposition 3

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

Commutative Algebra, chapter IV, § 1. Prime ideals associated with a module

Let AA be a ring, MM an AA-module and NN a submodule of NN. Then

Ass⁡(N)⊂Ass⁡(M)⊂Ass⁡(N)∪Ass⁡(M/N). \operatorname{Ass}(N) \subset \operatorname{Ass}(M) \subset \operatorname{Ass}(N) \cup \operatorname{Ass}(M/N).
The inclusion Ass⁡(N)⊂Ass⁡(M)\operatorname{Ass}(N) \subset \operatorname{Ass}(M) is obvious. Let p∈Ass⁡(M)p \in \operatorname{Ass}(M), EE be a submodule of MM isomorphic to A/pA/p and F=E∩NF = E \cap N. If F={0}F = \{0\}, EE is isomorphic to a submodule of M/NM/N, whence p∈Ass⁡(M/N)p \in \operatorname{Ass}(M/N). If F≠{0}F \neq \{0\}, the annihilator of every element ≠0\neq 0 of FF is pp (Proposition 1) and hence p∈Ass⁡(F)⊂Ass⁡(N)p \in \operatorname{Ass}(F) \subset \operatorname{Ass}(N).

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.