Kerodon

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

Remark 2.2.1.3. In the situation of Definition 2.2.1.1, we will refer to axiom $(P)$ as the pentagon identity.