Kerodon

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

Remark 3.5.1.3. Let $X$ be a finite simplicial set. Then any simplicial subset $Y \subseteq X$ is also finite. In particular, any retract of $X$ is finite.