Soft consensus and network dynamics in group decision making

We propose a dynamical network model for consensus reaching in group decision making. The model combines the minimization of a soft measure of collective dissensus and an individual inertial mechanism which emulates opinion changing aversion. Both components of the dynamics are nonlinear. The collective consensual trend corresponds to a process of anisotropic diffusion among the various individual preference structures. The anisotropy is designed so as to outline and enhance the natural group segmentation into homogeneous preference subgroups (weak consensus). The individual inertial mechanism, on the other hand, opposes changes from the original preferences and provides an appropriate framework to deal with preference outliers. We examine in detail the simple case in which each decision maker must choose between only two alternatives. Finally we comment on the possibility of incorporating in the dynamics a form of transitivity constraint regarding the group segmentation.