‘Don’t wait to be hunted to hide.’ –Samuel Beckett
One way to study a network is to break it down into its simplest pattern of links. These simple patterns are called motifs and their numbers usually depend on the type of network.
One of the big puzzles of network science is that some motifs crop up much more often than others. These motifs are clearly important. Remove them (or change their distribution) and the behaviour of the network changes too. But nobody knows why.
Today, Xiao-Ke Xu at Hong Kong Polytechnic University and friends say they know why and the answer is intimately linked to the existence of rich clubs within a network.
Let’s step back for a bit of background. In many networks, a small number of nodes are well connected to large number of others. The group of all well-connected nodes is known as the “rich club” and it is known to play an important role in the network of which it is part.
Rich clubs are particularly influential in a specific class of network in which the number of links between nodes varies in a way that is scale free (ie follows a power law).
This is an important class. It includes the internet, social networks, airline networks and many naturally occurring networks such as gene regulatory networks.
photo { Jimi Franklin }
