associativity of a tensor product for commutative rings
1. Proposition
Let \(R\) be a ring, \(M_1,M_2,M_3\) \(R\)-module. Then it holds for the tensor product
\begin{align*} ((M_1 \otimes M_2) \otimes M_3) \cong (M_1 \otimes (M_2 \otimes M_3)) \end{align*}2. Proof
follows from
TODO