$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.9
\begin{equation} \begin{gathered}\label{equation:cofinality-criterion} \xymatrix@C =50pt@R=50pt{ A \ar [r] \ar [d]^{F} & A^{\triangleleft } \ar [d]^{ F^{\triangleleft } } \\ B \ar [r] & B^{\triangleleft } } \end{gathered} \end{equation}