Introduction to Graphs - Practical Neo4j - page 4

In graph theory, the mainland and islands are what is referred to as vertices (the plural of vertex ). Each bridge
that connects two vertices is known as an edge , which, for the purposes of graph theory, serves to identify which pair
of vertices is connected by that bridge. As you can see in Figure 1-2 , the components of the problem are broken down
into four vertices connected by seven edges. The final mathematical structure that represents all the vertices and
edges is called a graph .

Figure 1-2. The Seven Bridges of Königsberg problem displayed as Euler's graph representation

■ a deep understanding of graph theory is not essential to working with graph databases. For those readers who
want to dive further into graph theory, richard J. trudeau's Introduction to Graph Theory (dover, 1993) provides a more
thorough discussion.

Note

A common mistake is to refer to the item in Figure 1-3 , and items similar to it, as a graph . Although graph data or
diagrams may be contained within a chart, the terms graph and chart are not synonymous.

Figure 1-3. Bar chart