Kerodon

\begin{equation} \begin{gathered}\label{equation:covariant-transport-path-fibrations} \xymatrix { \operatorname{\mathcal{C}}_{/X} \ar [r]^{ f \circ } \ar [d]^{ \delta _{/X} }_{\sim } & \operatorname{\mathcal{C}}_{/Y} \ar [d]^{\delta _{/Y} }_{\sim } \\ \operatorname{\mathcal{C}}\operatorname{\vec{\times }}_{ \operatorname{\mathcal{C}}} \{ X\} \ar [r]^{ f_{!} } & \operatorname{\mathcal{C}}\operatorname{\vec{\times }}_{\operatorname{\mathcal{C}}} \{ Y \} } \end{gathered} \end{equation}