\begin{definition}[Definition:Balanced Signed Graph]
Let $G = \struct {V, E}$ be a signed graph.
Then $G$ is '''balanced''' {{iff}} it is possible to partition $V$ into two subsets $A, B$ such that:
* the positive edges have both ends in $A$ or both ends in $B$;
* the negative edges have one end in $A$ and the other end $B$.
It is a frequent practice to apply a different colour to the vertices in each set to enhance clarity.
\end{definition}