Kerodon

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

Corollary 4.7.1.23. For every ordinal $\alpha $, $\mathrm{Ord}_{< \alpha }$ is a well-ordered set of order type $\alpha $.