Kerodon

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

Notation 3.1.4.9. Let $f: X_{} \rightarrow Y_{}$ be a morphism of simplicial sets. We let $[f]$ denote the homotopy class of $f$: that is, the image of $f$ in the set $\pi _0 \operatorname{Fun}( X_{}, Y_{} )$ of homotopy classes of maps from $X_{}$ to $Y_{}$.