Example 3.5.2.3. Let $X$ be a simplicial set, let $n$ be an integer, and let $\operatorname{sk}_{n}(X)$ denote the $n$-skeleton of $X$. Then the inclusion map $i: \operatorname{sk}_{n}(X) \hookrightarrow X$ is bijective on $m$-simplices for $m \leq n$. Applying Corollary 3.5.2.2, we conclude that $i$ is $n$-connective.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$