$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
5.3
\begin{equation} \begin{gathered}\label{equation:mapping-space-cartesian-diagram} \xymatrix@R =50pt@C=50pt{ \operatorname{Hom}_{\operatorname{\mathcal{C}}}(X,Y,Z) \times _{ \operatorname{Hom}_{\operatorname{\mathcal{C}}}(Y,Z) } \{ g\} \ar [r] \ar [d] & \operatorname{Hom}_{\operatorname{\mathcal{C}}}(X,Z) \ar [d] \\ \operatorname{Hom}_{\operatorname{\mathcal{D}}}( \overline{X}, \overline{Y}, \overline{Z} ) \times _{ \operatorname{Hom}_{\operatorname{\mathcal{D}}}( \overline{Y}, \overline{Z}) } \{ \overline{g} \} \ar [r] & \operatorname{Hom}_{\operatorname{\mathcal{D}}}( \overline{X}, \overline{Z} ) } \end{gathered} \end{equation}