Example 1.5.7.2. Let $G$ be the directed graph depicted in the diagram
\[ \xymatrix@R =50pt@C=50pt{ \bullet \ar [r] & \bullet \ar [r] & \bullet . } \]
Then the map $u: G_{\bullet } \rightarrow \operatorname{N}_{\bullet }( \operatorname{Path}[G] )$ can be identified with the inclusion of simplicial sets $\Lambda ^{2}_{1} \hookrightarrow \Delta ^2$. In this case, Theorem 1.5.7.1 reduces to the statement that the map
\[ \operatorname{Fun}( \Delta ^2, \operatorname{\mathcal{C}}) \rightarrow \operatorname{Fun}( \Lambda ^{2}_{1}, \operatorname{\mathcal{C}}) \]
is a trivial Kan fibration, which is equivalent to the assumption that $\operatorname{\mathcal{C}}$ is an $\infty $-category by virtue of Theorem 1.5.6.1.