Nerve of a category
= Nerve of a category
{title2=$N(\mathcal C)$}
{wiki=Nerve_(category_theory)}
The nerve of a category $\mathcal C$ has
$$
N(\mathcal C)_n=\operatorname{Fun}([n],\mathcal C),
$$
so an $n$-simplex is a string of $n$ composable morphisms. Every inner horn in a nerve has a unique filler.