dc.description.abstract | The notion of a network is ingrained in contemporary culture. In
everyday English parlance, we casually talk about television networks,
computer networks, professional networks, telephone networks, and
so on. Even though the word has a technological flavor, the idea of
a network is purely mathematical at its core. A network (or graph in
mathematical language) is an abstract model that consists of two kinds
of elements: nodes connected by links. The nodes of a network can represent social actors, cities, molecules, computers, words, and basically
anything we want to think about in terms of network theory. A link
represents some connection between two nodes, such as the friendship
between two people, a piece of wire connecting two machines, a shared
characteristic of two entities, a web link from one page to the other, or a
flight route between two cities.1
Figure 1 shows a widely used example
of a small social network, the friendship network of Zachary’s Karate
club, with nodes standing for members of the club and links representing
friendship ties between them. Once we decide what the nodes and the
links stand for, an abstract model of the underlying real-world phenomenon can be built that lends itself to further analysis (see below). | en_US |