Chapter 3

A graph is a collection of V nodes and E edges where an edge e is represented as a two-element subset {u, v}. Directed graphs represent an edge e in ordered pairs (u, v), which are not interchangeable. An undirected graph is essentially a default graph. Examples of graphs include transportation, communication, information(e.g. world wide web), social, and dependency networks. An important operation in graphs is traversing a sequence of nodes connected by edges. Traversal requires that a path, a sequence of of connected nodes, exist. An undirected graph is corrected if there exists a path between every pair of nodes. Interestingly, trees are undirected graphs that do not contain a cycle (the sequence of nodes does not cycle back to where it begins). Overall the section was a basic overview of graphs, and it's readability is an 8/10.