Definitions
An undirected graph is a pair (V,E), where V is a finite set, and E is a set of unordered pairs (u,v), where u different from v and both are in V.
Terminology: If (u,v) is an edge (i.e., in E)
- u and v are adjacent; v is a neighbor of u
A directed graph is a pair (V,E), where V is a finite set, and E is a set of ordered pairs (u,v) (u different from v, both in V).