Kerodon

$\Newextarrow{\xRightarrow}{5,5}{0x21D2}$
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
2.1
\begin{eqnarray} \label{equation:cocycle-identity} w( \alpha _{x,y,z} ) - \alpha _{wx,y,z} + \alpha _{w,xy,z} - \alpha _{w,x,yz} + \alpha _{w,x,y} = 0 \end{eqnarray}