Extracting Meaning From the Structure of Networks 31
Roland Piquepaille writes "Networks are used to represent the structure of complex systems, including the Internet or social networks, but often these descriptions are biased or incomplete. Now, researchers at the Santa Fe Institute (SFI) have shown that it's possible to extract automatically the hierarchical structure of networks. The researchers say their results 'suggest that hierarchy is a central organizing principle of complex networks, capable of offering insight into many network phenomena.' They also think that their algorithms can be applied to almost every kind of networks, from biochemical networks (protein interaction networks, metabolic networks or genetic regulatory networks) to communities in social networks. But read more for additional references and some pictures about hierarchical networks and their applications."
Re:Can we get a Roland filter? (Score:4, Interesting)
In the context of the research (using known parts of a network's structure to predict unknown parts), I don't think the word "meaning" is out of place at all. A hierarchical clustering algorithm will extract some kind of hierarchy from any network you throw at it - but does that hierarchy mean anything? Does it contain information? This new research suggests that, for certain kinds of network, the extracted hierarchy is meaningful, because it allows us to make predictions about unknown parts of the network that we could not make without first extracting the hierarchy.
That's actually quite a profound discovery, because in the last ten years, complex networks (especially small-world and scale-free networks) have been held up as models of natural decentralisation and non-hierarchical self-organisation in many fields, from ecology to politics to communications to epidemiology. If such networks turn out to contain meaningful hierarchies (i.e. hierarchies that actually tell us something about how they function) then much of the rhetoric about complex systems will be turned on its head.