Definition 1.5.4.6. Let $\operatorname{\mathcal{C}}$ be a category containing a pair of objects $C$ and $C'$. We will say that $C$ is a retract of $C'$ if there exist maps $i: C \rightarrow C'$ and $r: C' \rightarrow C$ such that $r \circ i = \operatorname{id}_{C}$.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$