Kerodon

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

Remark 4.1.2.3. Let $f: A \rightarrow B$ be a morphism of simplicial sets. Then $f$ is left anodyne if and only if the opposite morphism $f^{\operatorname{op}}: A^{\operatorname{op}} \rightarrow B^{\operatorname{op}}$ is right anodyne.