Corollary 4.3.6.10. Let $q: X \rightarrow S$ be an inner fibration of simplicial sets and let $f: K \rightarrow X$ be any morphism of simplicial sets. Then the induced maps
\[ X_{/f} \rightarrow S_{ / (q \circ f)} \quad \quad X_{f/} \rightarrow S_{(q \circ f)/} \]
are inner fibrations.