Bourbaki

Proposition 7

Tag 0D4G, permanent. Cite it as [Bourbaki, Tag 0D4G].

Commutative Algebra, chapter X, § 3. Profondeur et dimension homologique

Let AA be a ring, xx a cancellable element of AA, MM an AA-module such that the homothety xMx_M is injective, NN an AA-module annihilated by xx, nn an integer. The canonical homomorphisms of (A/xA)(A/xA)-modules

ExtA/xAn(M/xM,N)⟶ExtAn(M,N), \mathrm{Ext}^n_{A/xA}(M/xM, N) \longrightarrow \mathrm{Ext}^n_A(M, N),
ExtAn(N,M)⟶ExtA/xAn−1(N,M/xM), \mathrm{Ext}^n_A(N, M) \longrightarrow \mathrm{Ext}^{n-1}_{A/xA}(N, M/xM),
TornA(M,N)⟶TornA/xA(M/xM,N) \mathrm{Tor}^A_n(M, N) \longrightarrow \mathrm{Tor}^{A/xA}_n(M/xM, N)

deduced from the exact sequences (4), (5) and (6) are isomorphisms.

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

Cited by

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Cites

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Translated with machine help, not yet reviewed by a person.