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Remark Suppose we are given a lifting problem in the category of simplicial sets

\begin{equation} \begin{gathered}\label{equation:typical-lifting-problem} \xymatrix@R =50pt@C=50pt{ A \ar [r]^-{f_0} \ar [d]^{i} & X \ar [d]^{q} \\ B \ar [r]^-{ \overline{f} } \ar@ {-->}[ur] & S, } \end{gathered} \end{equation}

where $q$ is an isofibration and $i$ is a monomorphism. It follows from Corollary that, if we regard the morphisms $q$, $i$, and $\overline{f}$ as fixed, then the existence of a solution to the lifting problem (4.39) depends only on the isomorphism class of $f$ as an object of the $\infty $-category $\operatorname{Fun}_{/S}(A,X)$.