# Kerodon

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

Warning 5.3.6.7. The analogue of Proposition 5.3.6.6 for the two-out-of-three property is false in general. For example, if $\operatorname{\mathcal{C}}$ is the nerve of a category, then the collection of identity morphisms of $\operatorname{\mathcal{C}}$ has the two-out-of-three property, but usually does not contain all the isomorphisms of $\operatorname{\mathcal{C}}$.