# Kerodon

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Remark 5.5.3.5 (Functoriality in $\operatorname{\mathcal{C}}$). Let $\operatorname{\mathcal{C}}$ be a category equipped with a functor $\mathscr {F}: \operatorname{\mathcal{C}}\rightarrow \operatorname{Set_{\Delta }}$, let $U: \operatorname{\mathcal{C}}' \rightarrow \operatorname{\mathcal{C}}$ be a functor between categories, and let $\mathscr {F}': \operatorname{\mathcal{C}}' \rightarrow \operatorname{Set_{\Delta }}$ denote the composition $\mathscr {F} \circ U$. Then there is a pullback diagram of simplicial sets

$\xymatrix@R =50pt@C=50pt{ \int ^{\mathrm{s}}_{\operatorname{\mathcal{C}}'}\mathscr {F}' \ar [r] \ar [d] & \int ^{\mathrm{s}}_{\operatorname{\mathcal{C}}}\mathscr {F} \ar [d] \\ \operatorname{N}_{\bullet }( \operatorname{\mathcal{C}}' ) \ar [r]^-{ \operatorname{N}_{\bullet }(U) } & \operatorname{N}_{\bullet }(\operatorname{\mathcal{C}}). }$