Remark 11.10.7.2. In the situation of Definition 11.10.7.1, the morphism $f: X \rightarrow Y$ is a covariant equivalence relative to $S$ if and only if the opposite morphism $f^{\operatorname{op}}: X^{\operatorname{op}} \rightarrow Y^{\operatorname{op}}$ is a contravariant equivalence relative to $S^{\operatorname{op}}$.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$