A graph G is a pair (V,E) where

• V is a set of vertices
• E is a set of edges

FWGC Example:

• V = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
• E = {(1,7), (7,4), (4,10), (10,3), (3,9), (4,8), (8,5), (5,9), (9,2), (2,6)}

E is a binary relation on V.

• If the edges in E are unordered pairs (u,v), the graph G is undirected
• If the edges in E are ordered pairs ⟨u,v⟩, the graph G is directed