2.2 Representation of Networks
Networks are represented as sets of nodes and edges drawn between the nodes; thus, networks are essentially similar to “graphs” in mathematics. Examples of networks representing real-world systems are listed in Table 2.1.
Network | Nodes | Edges |
Internet | Computer or router | Cable or wireless data connection |
World Wide Web | Web page | Hyperlink |
Citation relationship | Article, patent, or legal case | Citation |
Power grid | Generating station or substation | Transmission line |
Friendship network | Person | Friendship |
Metabolism | Metabolite | Metabolic reaction |
Food web | Species | Predation |
There are several types of networks (graphs); the major types are shown in Figure 2.1.
In the simplest case, networks are represented as shown in Figure 2.1a. The relationship (or interaction) between two given nodes is represented in a network by drawing edges between the nodes. In this case, multiedges, which refer to multiple edges between the same pair of nodes, and self-edges, in which the source is identical to the target, are neglected for simplicity. However, the above-mentioned ...
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