Proposition 10.3.1.33. Let $\operatorname{\mathcal{C}}$ be an $\infty $-category and let $f: X \rightarrow Y$ be a morphism of $\operatorname{\mathcal{C}}$. For every dense sieve $\operatorname{\mathcal{C}}^{0}_{/Y} \subseteq \operatorname{\mathcal{C}}_{/Y}$, the pullback sieve $f^{\ast } \operatorname{\mathcal{C}}^{0}_{/Y} \subseteq \operatorname{\mathcal{C}}_{/X}$ is also dense.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
Proof. This is an immediate consequence of the criterion of Remark 10.3.1.32. $\square$