Editing Graph theory (section)

=== Other topics ===
A graph structure can be extended by assigning a weight to each edge of the graph. Graphs with weights, or [[weighted graph]]s, are used to represent structures in which pairwise connections have some numerical values. For example, if a graph represents a road network, the weights could represent the length of each road. There may be several weights associated with each edge, including distance (as in the previous example), travel time, or monetary cost. Such weighted graphs are commonly used to program GPS's, and travel-planning search engines that compare flight times and costs.