$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.42
\begin{equation} \begin{gathered}\label{equation::relative-Kan-extension-existence-transitivity3} \xymatrix@R =50pt@C=50pt{ \operatorname{\mathcal{C}}_{/C} \ar [d] \ar [r]^-{F_{C}} & \operatorname{\mathcal{D}}\ar [d]^{U} \\ (\operatorname{\mathcal{C}}_{/C})^{\triangleright } \ar [r] \ar@ {-->}[ur]^{ \overline{F}_{C} } & \operatorname{\mathcal{E}}} \end{gathered} \end{equation}