Kerodon

$\Newextarrow{\xRightarrow}{5,5}{0x21D2}$
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$

Remark 3.5.1.5. Let $f: X \twoheadrightarrow Y$ be an epimorphism of simplicial sets. If $X$ is finite, then $Y$ is also finite.