Reading 12 : Graphs

Graphs are discrete structures that model relationships between objects. Graphs play an important role in many areas of computer science. In this reading we introduce basic notions of graph theory that are important in computer science. In particular we look directed graphs, undirected graphs, trees and some applications of graphs. We begin by discussing directed graphs, also known as digraphs. The definition below uses the term multiset. A multiset is a collection very similar to a set, except duplicates of an element are allowed. Every set is also a multiset, but there are some multisets that are not sets. For example {1, 2, 3} is a set and also a multiset. On the other hand, {1, 1, 2} is a multiset, but not a set.