Bourbaki

Corollary

Tag 061T, permanent. Cite it as [Bourbaki, Tag 061T].

Algebra, chapter III, § 5. Tensor algebra. Tensors

If MM is a projective AA-module, T(M)T(M) is a projective AA-module.

MM is a direct factor of a free AA-module NN (II, § 2, no. 2, Proposition 4) and hence T(M)T(M) is a direct factor of T(N)T(N) (no. 2); as T(N)T(N) is free (Theorem 1), this shows that T(M)T(M) is projective (II, § 2, no. 2).

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

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Cites

Transcribed from the printed edition, 1998, Springer. Not translated.