Networks

Many complex systems can be described and analyzed as a network — a set of individual components (called "nodes"), each connected to at least one other in a web of interactions. Flights connect airports in an air transportation network. The life-enabling chemical process that converts resources to energy is a reaction network known as metabolism. The web of funding relationships among world terrorist groups is a network. The power grid is an energy supply network. Facebook is a social network.

When a complex system is described as a network, the number of nodes and the nature of their connections can be studied mathematically. Questions SFI researchers are asking include how is a network's structure related to its function and behavior; how can the nodes or groups of nodes most important to a system’s function be detected (and can that knowledge help improve the network’s reliability or resilience); and why and how do hubs arise, bottlenecks swell, subnetworks cluster, or networks cleave?