Kerodon

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

Remark 1.1.3.4. Let $f: S \twoheadrightarrow T$ be an epimorphism of simplicial sets. If $S$ has dimension $\leq n$, then $T$ has dimension $\leq n$.