Kerodon

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

Example 3.5.7.4. A Kan complex $X$ is $(-1)$-truncated if and only if it is either empty or contractible.