$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
5.2
\begin{equation} \label{equation:lifting-problem-cartesian-2-simplex} \begin{gathered}\xymatrix@R =50pt@C=50pt{ \Lambda ^{2}_{2} \ar [r]^-{\sigma _0} \ar [d] & \operatorname{N}_{\bullet }(\operatorname{\mathcal{E}}) \ar [d]^-{ \operatorname{N}_{\bullet }(U)} \\ \Delta ^{2} \ar [r] \ar@ {-->}[ur]^{\sigma } & \operatorname{N}_{\bullet }(\operatorname{\mathcal{C}}) } \end{gathered} \end{equation}