$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
6.16
\begin{equation} \begin{gathered}\label{equation:resolution-of-sset} \xymatrix@R =50pt@C=50pt{ \widetilde{\operatorname{sk}}_{k-1}(S) \times \widetilde{T}_0^{\triangleright } \ar [d] & \widetilde{T}_0 \ar [l] \ar [r] \ar [d] & T \times \widetilde{T}_0^{\triangleright } \ar [d] \\ \operatorname{sk}_{k-1}(S) & T_0 \ar [l] \ar [r] & T. } \end{gathered} \end{equation}