Corollary 5.1.5.11. Let $p: X \rightarrow S$ be an inner fibration of simplicial sets. Then $p$ is a cartesian fibration if and only if every pullback $X \times _{S} \Delta ^ n \rightarrow \Delta ^ n$ is a cartesian fibration for $n \leq 2$.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$