MERCREDI 8 AVRIL 2009
14 heures
Salle Séminaire 5
Centre de Physique Théorique
Marseille-Luminy

Timoteo Carletti
Department of Mathematics FUNDP, Namur, Belgique

Title: Opinion dynamics: friendship and social temperature

Abstract: We propose a model of opinion dynamics model where agents
adjust their current opinion as a result of random encounters,
allowing to study the mechanism of group formation under the pressure
of two antagonist forces: friendship and social temperature. Every
agent is characterized by a scalar continuous opinion about a given
subject and his friendship relations with other agents (roughly
speaking a measures of the mutual trust). The important fact is that
both quantities evolve in time in a non trivial way.

As a result of the interactions, clusters of individuals sharing the
same opinion and displaying high affinity-friendship values are
formed. The distribution of the clusters is monitored and a second
order phase transition detected, marking the distinction between a
full connected group and a fragmented population. The control
parameter is represented by an effective radius that specifies the
range of the interaction between agents. The system relaxation time is
also computed and a close analytical estimate derived.

Our results can be restated as a opinion model developing on a social
network where the network itself is not a static one but it evolves,
being the affinity-friendship matrix strictly related to the adjacency
matrix. Moreover we are able to analytically describe the network
evolution in terms of its topological parameters (i.e. mean degree,
clustering coefficient, mean path, diameter).