Line graph of a regular graph is Eulerian
= Line graph of a regular graph is Eulerian
If $G$ is connected and $r$-regular, then $L(G)$ is connected and every one of its vertices has degree $2r-2$. The <Euler circuit criterion> therefore applies.
= Line graph of a regular graph is Eulerian
If $G$ is connected and $r$-regular, then $L(G)$ is connected and every one of its vertices has degree $2r-2$. The <Euler circuit criterion> therefore applies.