Eun Lee

Impact of mobility structure on optimization of small-world networks of mobile agents

AbstractnIn ad hoc wireless networking, units are connected to each other rather than to ancentral, fixed, infrastructure. Constructing and maintaining such networks create severalntrade-off problems between robustness, communication speed, power consumption, etc., thatnbridges engineering, computer science and the physics of complex systems. In this work, wenaddress the role of mobility patterns of the agents on the optimal tuning of a small-worldntype network construction method. By this method, the network is updated periodically andnheld static between the updates. We investigate the optimal updating times for differentnscenarios of the movement of agents (modeling, for example, the fat-tailed trip distances,nand periodicities, of human travel). We find that these mobility patterns affect the powernconsumption in non-trivial ways and discuss how these effects can best be handled.n

Social contagion with degree-dependent thresholds

We investigate opinion spreading by a threshold model in a situation in which the influence of people is heterogeneously distributed. We assume that there is a coupling between the influence of an individual (measured by the out-degree) and the threshold for accepting a new opinion or habit. We find that if the coupling is strongly positive, the final state of the system will be a mix of different opinions. Otherwise, it will converge to a consensus state. This phenomenon cannot simply be explained as a phase transition, but it is a combined effect of mechanisms and their relative dominance in different regions of parameter space.

Modeling the dynamics of dissent

We investigate the formation of opinion against authority in an authoritarian society composed of agents with different levels of authority. We explore a “dissenting” opinion, held by lower-ranking, obedient, or less authoritative people, spreading in an environment of an “affirmative” opinion held by authoritative leaders. A real-world example would be a corrupt society where people revolt against such leaders, but it can be applied to more general situations. In our model, agents can change their opinion depending on their authority relative to their neighbors and their own confidence level. In addition, with a certain probability, agents can override the affirmative opinion to take the dissenting opinion of a neighbor. Based on analytic derivation and numerical simulations, we observe that both the network structure and heterogeneity in authority, and their correlation, significantly affect the possibility of the dissenting opinion to spread through the population. In particular, the dissenting opinion is suppressed when the authority distribution is very heterogeneous and there exists a positive correlation between the authority and the number of neighbors of people (degree). Except for such an extreme case, though, spreading of the dissenting opinion takes place when people have the tendency to override the authority to hold the dissenting opinion, but the dissenting opinion can take a long time to spread to the entire society, depending on the model parameters. We argue that the internal social structure of agents sets the scale of the time to reach consensus, based on the analysis of the underlying structural properties of opinion spreading.