Remark 10.3.4.4. Let $\operatorname{\mathcal{C}}$ be an $\infty $-category, let $Y$ be an object of $\operatorname{\mathcal{C}}$, and let $\operatorname{\mathcal{C}}^{0}_{/Y} \subseteq \operatorname{\mathcal{C}}_{/Y}$ be a sieve on $Y$. If $\operatorname{\mathcal{C}}^{0}_{/Y}$ contains a universal quotient morphism $f: X \twoheadrightarrow Y$, then it is dense. See Remark 10.3.1.31.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$