Kerodon

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

Example 3.5.7.27. Let $f: X \rightarrow Y$ be a morphism of Kan complexes. For $n \leq -2$, $f$ exhibits $Y$ as an $n$-truncation of $X$ if and only if $Y$ is contractible. See Example 3.5.7.3.