Intuition
A graph is a set of vertices connected by edges.
Notation
Let \(G=(V,A)\), where:
- \(V=\{A,B,C,D,E\}\) is the set of vertices;
- \(A\) is the set of edges (unordered pairs of vertices).
In this example, one possible edge set is:
\[
A=\{\{A,B\},\{B,C\},\{A,C\},\{A,D\},\{C,D\},\{B,E\},\{D,E\}\}
\]