$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
3.73
\begin{equation} \begin{gathered}\label{equation:strong-coskeleton-vs} \xymatrix@R =50pt@C=50pt{ \operatorname{\partial \Delta }^{m} \ar [r]^-{\sigma _0} \ar [d] & \operatorname{cosk}_{n+1}(X) \ar [d]^{q} \\ \Delta ^{m} \ar [r]^-{\overline{\sigma }} \ar@ {-->}[ur]^{\sigma } & \operatorname{cosk}_{n}^{\circ }(X) } \end{gathered} \end{equation}