$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.68
\begin{equation} \begin{gathered}\label{equation:retracts-and-idempotents} \xymatrix@R =50pt@C=50pt{ & X \ar [dr]^{r} & \\ Y \ar [ur]^{i} \ar [rr]^{ \operatorname{id}_{Y} } & & Y } \end{gathered} \end{equation}