# Kerodon

$\Newextarrow{\xRightarrow}{5,5}{0x21D2}$

Warning 4.2.5.4. The requirement that a functor $F: \operatorname{\mathcal{C}}\rightarrow \operatorname{\mathcal{D}}$ is a fibration in groupoids is not invariant under equivalence. For example, an equivalence of categories need not be a fibration in groupoids.