Bourbaki

Proposition 12

Tag 0D12, permanent. Cite it as [Bourbaki, Tag 0D12].

Commutative Algebra, chapter X, § 1. Profondeur

Let A be a noetherian local ring, M a nonzero finitely generated A-module and J an ideal of A distinct from A. One has the sequence of inequalities

prof⁡A(J;M)≤codim⁡(Supp⁡(M)∩V(J),Supp⁡(M))≤dim⁡(M)−dim⁡(M/JM) \operatorname{prof}_A(J; M) \leq \operatorname{codim}(\operatorname{Supp}(M) \cap V(J), \operatorname{Supp}(M)) \leq \dim(M) - \dim(M/JM)
≤[J/mAJ:κA]. \leq [J/m_A J : \kappa_A].

For every element pp of Supp⁡(M)∩V(J)\operatorname{Supp}(M) \cap V(J), prof⁡A(J;M)\operatorname{prof}_A(J; M) is less than or equal to dim⁡Ap(Mp)\dim_{A_p}(M_p) (No. 5, Prop. 8 and No. 4, Cor. 2 of Th. 2), that is to say (VIII, § 1, No. 4, Prop. 9)

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

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