$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
4.14
\begin{equation} \begin{gathered}\label{equation:join-of-inner-fibration} \xymatrix@R =50pt@C=50pt{ \Lambda ^{n}_{i} \ar [r]^-{ \sigma _0 } \ar [d] & X \star Y \ar [d]^{u \star v } \\ \Delta ^{n} \ar [r]^-{ \sigma ' } \ar@ {-->}[ur]^{ \sigma } & X' \star Y' } \end{gathered} \end{equation}