$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
5.23
\begin{equation} \begin{gathered}\label{equation:cocartesian-in-relative-join} \xymatrix@R =50pt@C=50pt{ \Lambda ^{n}_{0} \ar [r]^-{\sigma _0} \ar [d] & \operatorname{\mathcal{C}}\star _{\operatorname{\mathcal{D}}} \operatorname{\mathcal{D}}\ar [d]^-{W} \\ \Delta ^{n} \ar@ {-->}[ur]^{\sigma } \ar [r]^-{ \sigma ' } & \operatorname{\mathcal{C}}' \star _{\operatorname{\mathcal{D}}'} \operatorname{\mathcal{D}}',} \end{gathered} \end{equation}