Corollaire 1

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

a) The connecting homomorphism $\mathrm{Hom}_A(M'', M'') \to \mathrm{Ext}_A^1(M'', M')$ sends $1_{M''}$ to $\theta$ .

b) The connecting homomorphism $\mathrm{Hom}_A(M', M') \to \mathrm{Ext}_A^1(M'', M')$ sends $1_{M'}$ to $-\theta$ .

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

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