Notation 2.5.0.4. Let $k$ be a commutative ring. We will write $\operatorname{Ch}(k)$ for the category $\operatorname{Ch}(\operatorname{\mathcal{A}})$, where $\operatorname{\mathcal{A}}$ is the category of $k$-modules and $k$-module homomorphisms. In particular, we will write $\operatorname{Ch}(\operatorname{\mathbf{Z}})$ for the category of chain complexes of abelian groups.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$