$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.58
\begin{equation} \begin{gathered}\label{equation:disagreement-of-fiber-products} \xymatrix@R =50pt@C=50pt{ X_{s} \ar [r] \ar [d] & X \ar [d]^-{q} \\ \{ s\} \ar [r] & S } \end{gathered} \end{equation}