$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.58
\begin{equation} \begin{gathered}\label{equation:Hom-in-oriented-fiber-product} \xymatrix@R =50pt@C=50pt{ \operatorname{Hom}_{\operatorname{\mathcal{C}}_{\pm }}( \bullet , \bullet ) \ar [r] \ar [d] & \operatorname{Hom}_{ \operatorname{\mathcal{C}}_{+} }( \operatorname{ev}_{+}( \bullet ), \operatorname{ev}_{+}( \bullet ) ) \ar [d] \\ \operatorname{Hom}_{\operatorname{\mathcal{C}}_{-}}( \operatorname{ev}_{-}(\bullet ), \operatorname{ev}_{-}(\bullet ) ) \ar [r] & \operatorname{Hom}_{ \operatorname{\mathcal{C}}}( (F_{-} \circ \operatorname{ev}_-)(\bullet ), (F_{+} \circ \operatorname{ev}_+)(\bullet ) ) } \end{gathered} \end{equation}