# Kerodon

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

Example 5.1.4.3. Let $X$ be a simplicial set and let $q: X \rightarrow \Delta ^0$ denote the projection map. The following conditions are equivalent:

• The simplicial set $X$ is an $\infty$-category.

• The morphism $q$ is a cartesian fibration.

• The morphism $q$ is a cocartesian fibration.