$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.37
\begin{equation} \begin{gathered}\label{equation:relative-colimit-extension-criterion} \xymatrix@R =50pt@C=50pt{ \operatorname{\mathcal{C}}\ar [d] \ar [r]^-{F} & \operatorname{\mathcal{D}}\ar [d]^{U} \\ \operatorname{\mathcal{C}}^{\triangleright } \ar [r] \ar@ {-->}[ur]^{ \overline{F} } & \operatorname{\mathcal{E}}. } \end{gathered} \end{equation}