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Graph G=(V,E) is set of vertices (nodes) V and edges (links) E.
Applications: networks or problems with connectivity.
Graphs: Terminology [168]
G is directed or undirected (both directions) based on edges.
Weights (cost, distance) may be associated with each edge.
Path is a sequence of vertices w_1, w_2,...,
Length is the number of edges in the path.
G may have cycles or be acyclic.
Directed acyclic graph: DAG
Undirected G is connected if path from every v to every other w.
Directed G is called strongly connected in this case.
If direction removed and G is connected, this is weakly connected.
Complete G has an edge between every pair of vertices.