Speaker
Dr
Sune Lehmann
(Technical University of Denmark)
Description
We know that communities in networks often overlap such that
nodes simultaneously belong to several groups. Additionally,
many networks are known to possess hierarchical
organization, where communities are recursively grouped into
a hierarchical structure. However, when each and every node
belongs to more than one group, a single global hierarchy of
nodes cannot capture the relationships between overlapping
groups. Here we define communities as groups of links rather
than nodes and show that this approach reconciles the ideas
underlying overlapping communities and hierarchical
organization. Link communities naturally incorporate overlap
while revealing hierarchical organization. We discuss the
proper validation of detected communities and show examples
of relevant link communities in a number of networks,
including major biological networks such as protein–protein
interaction and metabolic networks, and show that a large
social network contains hierarchically organized community
structures spanning inner-city to regional scales while
maintaining pervasive overlap.
