$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.4
\begin{equation} \begin{gathered}\label{equation:homotopy-transport-twisted-arrow} \xymatrix@R =50pt@C=50pt{ h^{X} \ar [d] \ar [r]^-{\alpha _{X,-}} & H^{X} \ar [d] \\ h^{W} \ar [r]^-{ \alpha _{X,-} } & H^{W}, } \end{gathered} \end{equation}