Networks and communities:

Patterns of connections in complex systems

Many complex systems can be usefully represented as networks, such as social networks, computer networks, and information networks. In recent years researchers have performed some impressive empirical studies of these systems which have yielded large volumes of complex network data, and we have been using these data to probe the structure of networked systems, focusing particularly on the way the systems subdivide into groups or communities of nodes. In this talk I will discuss a variety of methods we have developed for probing community structure in networks, and some of the conclusions that we draw from our results.