$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
11.18
\begin{equation} \begin{gathered}\label{equation:covariant-equivalence-over-Kan} \xymatrix@C =50pt@R=50pt{ \operatorname{Fun}(Y,Z) \ar [r]^-{\circ f} \ar [d]^{q \circ } & \operatorname{Fun}(X,Z) \ar [d]^{q \circ } \\ \operatorname{Fun}(Y,S) \ar [r]^-{\circ f} & \operatorname{Fun}(X,S). } \end{gathered} \end{equation}