Kerodon

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

Example 3.1.4.13. Let $X$ be a simplicial set. Then the unique morphism $f: X \rightarrow \Delta ^{0}$ is a covering map of simplicial sets if and only if $X$ is discrete (see Definition 1.1.4.9).