$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
4.70
\begin{equation} \begin{gathered}\label{equation:homotopy-composition-diagram} \xymatrix@R =50pt@C=30pt{ \operatorname{Hom}_{\operatorname{\mathcal{C}}}(Y,Z) \times \operatorname{Hom}_{\operatorname{\mathcal{C}}}(X,Y) \times \operatorname{Hom}_{\operatorname{\mathcal{C}}}(W,X) \ar [r]^-{\circ } \ar [d]^{\circ } & \operatorname{Hom}_{\operatorname{\mathcal{C}}}(X,Z) \times \operatorname{Hom}_{\operatorname{\mathcal{C}}}(W,X) \ar [d]^{\circ } \\ \operatorname{Hom}_{\operatorname{\mathcal{C}}}(Y,Z) \times \operatorname{Hom}_{\operatorname{\mathcal{C}}}(W,Y) \ar [r]^-{\circ } & \operatorname{Hom}_{\operatorname{\mathcal{C}}}(W,Z) } \end{gathered} \end{equation}