$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
3.80
\begin{equation} \begin{gathered}\label{equation:truncated-nonsense} \xymatrix@R =50pt@C=50pt{ \operatorname{Fun}( \operatorname{\partial \Delta }^{k}, X ) \ar [r]^-{T} \ar [d] & \operatorname{Fun}( \Lambda ^{k}_{k}, X) \ar [d] \\ \operatorname{Fun}( \Delta ^{k-1}, X) \ar [r]^-{ R_{k-1} } & \operatorname{Fun}( \operatorname{\partial \Delta }^{k-1}, X). } \end{gathered} \end{equation}