Remark 7.4.1.5. Suppose we are given a pullback diagram of small simplicial sets
Then the covariant diffraction functor $\mathrm{Df}: \overline{\operatorname{\mathcal{E}}}_{ {\bf 0} } \rightarrow \operatorname{Fun}_{/ \operatorname{\mathcal{C}}}^{\operatorname{CCart}}( \operatorname{\mathcal{C}}, \operatorname{\mathcal{E}})$ of Construction 7.4.1.3 is an equivalence of $\infty $-categories if and only if the covariant transport representation $\operatorname{Tr}_{ \overline{\operatorname{\mathcal{E}}} / \operatorname{\mathcal{C}}^{\triangleleft } }: \operatorname{\mathcal{C}}^{\triangleleft } \rightarrow \operatorname{\mathcal{QC}}$ is a limit diagram in the $\infty $-category $\operatorname{\mathcal{QC}}$ (this is a restatement of Theorem 7.4.1.1).