Kerodon

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3.66
\begin{equation} \label{equation:unit-of-realization-2} \begin{gathered} \xymatrix@R =50pt@C=50pt{ \operatorname{Sing}_{\bullet }(|\operatorname{\partial \Delta }^{n}|) \ar [r] \ar [d] & \operatorname{Sing}_{\bullet }(|\Delta ^ n|) \ar [d] \\ \operatorname{Sing}_{\bullet }(|X'|) \ar [r] & \operatorname{Sing}_{\bullet }(|X|), }\end{gathered} \end{equation}