Complex Networks

Graphs can be in general use to represent Complex Systems where many elements are interacting between them. The nodes correspond to elements and the links to pairwise interactions. An example can be seen on the left. The network is the so called Zachary karate club for which nodes are people since these data proceeds from a sociological study. Students, teachers and administrators of a college karate club that suffered a strong conflict that led to the club excision in two groups. Node colors in the graph describe the final faction of each individual. |

The Zachary club network has become in clustering literature a classic for the use of graphs

in understanding
social conflicts. The graph representation permits to put the question of

finding the groups after the excision in a sound mathematical form. Given the graph of interactions,

are we able to find structure in it? Do such structures
reflect real world processes underlying the

evolution of the whole system?

These are the type of questions that, in a more general framework, are faced in the section

of my work titled Network
Structure Inference.