Bourbaki

Remark 4

Tag 00DE, permanent. Cite it as [Bourbaki, Tag 00DE].

Algebra, VIII, p. 192, § 11. Grothendieck Groups

We keep the assumptions and notation of Proposition 8. Let E be an A-module of finite length, and let a1A,...,anAa_1A, . . . , a_nA be its invariant factors (VII, §4, No. 5, p. 20). Since E is isomorphic to ⨁i=1nA/aiA\bigoplus_{i=1}^nA/a_iA, we have

φ([E])=∏i=1nφ([A/aiA])=a1⋯anA∗(10) \varphi ([E]) =\prod_{i=1}^n\varphi ([A/a_iA]) =a_1\cdots a_nA^* \tag{10}

Bourbaki sets the proof directly after the statement, and the corpus does not separate them, so what is above is the statement and its proof together.

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Cites

Transcribed from the printed edition, 2023, Springer Nature. Not translated.