Opinion Dynamics in Social Networks with Hostile Camps: Consensus vs. Polarization

Most of the distributed protocols for multi-agent consensus assume that the agents are mutually cooperative and "trustful," and so the couplings among the agents bring the values of their states closer. Opinion dynamics in social groups, however, require beyond these conventional models due to ubiquitous competition and distrust between some pairs of agents, which are usually characterized by repulsive couplings and may lead to clustering of the opinions. A simple yet insightful model of opinion dynamics with both attractive and repulsive couplings was proposed recently by C. Altafini, who examined first-order consensus algorithms over static signed graphs. This protocol establishes modulus consensus, where the opinions become the same in modulus but may differ in signs. In this paper, we extend the modulus consensus model to the case where the network topology is an arbitrary time-varying signed graph and prove reaching modulus consensus under mild sufficient conditions of uniform connectivity of the graph. For cut-balanced graphs, not only sufficient, but also necessary conditions for modulus consensus are given.Comment: scheduled for publication in IEEE Transactions on Automatic Control, 2016, vol. 61, no. 7 (accepted in August 2015

Flocking with Obstacle Avoidance

In this paper, we provide a dynamic graph theoretical framework for flocking in presence of multiple obstacles. In particular, we give formal definitions of nets and flocks as spatially induced graphs. We provide models of nets and flocks and discuss the realization/embedding issues related to structural nets and flocks. This allows task representation and execution for a network of agents called alpha-agents. We also consider flocking in the presence of multiple obstacles. This task is achieved by introducing two other types of agents called beta-agents and gamma-agents. This framework enables us to address split/rejoin and squeezing maneuvers for nets/flocks of dynamic agents that communicate with each other. The problems arising from switching topology of these networks of mobile agents make the analysis and design of the decision-making protocols for such networks rather challenging. We provide simulation results that demonstrate the effectiveness of our theoretical and computational tools

Short versus long term benefits and the evolution of cooperation in the prisoner's dilemma game

In this paper I investigate the evolution of cooperation in the prisoner's dilemma when individuals change their strategies subject to performance evaluation of their neighbours over variable time horizons. In the monochrome setting, in which all agents per default share the same performance evaluation rule, weighing past events strongly dramatically enhances the prevalence of cooperators. For co-evolutionary models, in which evaluation time horizons and strategies can co-evolve, I demonstrate that cooperation naturally associates with long-term evaluation of others while defection is typically paired with very short time horizons. Moreover, considering the continuous spectrum in between enhanced and discounted weights of past performance, cooperation is optimally supported when cooperators neither give enhanced weight to past nor more recent events, but simply average payoffs. Payoff averaging is also found to emerge as the dominant strategy for cooperators in co-evolutionary models, thus proposing a natural route to the evolution of cooperation in viscous populations

The role of supply chain integration in achieving competitive advantage: A study of UK automobile manufacturers

The competitive nature of the global automobile industry has resulted in a battle for efficiency and consistency in supply chain management (SCM). For manufacturers, the diversified network of suppliers represents more than just a production system; it is a strategic asset that must be managed, evaluated, and revised in order to attain competitive advantage. One capability that has become an increasingly essential means of alignment and assessment is supply chain integration (SCI). Through such practices, manufacturers create informational capital that is inimitable, yet transferrable, allowing suppliers to participate in a mutually-beneficial system of performance-centred outcomes. From cost reduction to time improvements to quality control, the benefits of SCI extend throughout the supply chain lifecycle, providing firms with improved predictability, flexibility, and responsiveness. Yet in spite of such benefits, key limitations including exposure to risks, supplier failures, or changing competitive conditions may expose manufacturers to a vulnerable position that can severely impact value and performance. The current study summarizes the perspectives and predictions of managers within the automobile industry in the UK, highlighting a dynamic model of interdependency and interpolation that embraces SCI as a strategic resource. Full commitment to integration is critical to achieving improved outcomes and performance; therefore, firms seeking to integrate throughout their extended supply chain must be willing to embrace a less centralized locus of control

Why we interact : on the functional role of the striatum in the subjective experience of social interaction

Acknowledgments We thank Neil Macrae and Axel Cleeremans for comments on earlier versions of this manuscript. Furthermore, we are grateful to Dorothé Krug and Barbara Elghahwagi for their assistance in data acquisition. This study was supported by a grant of the Köln Fortune Program of the Medical Faculty at the University of Cologne to L.S. and by a grant “Other Minds” of the German Ministry of Research and Education to K.V.Peer reviewedPreprin

Searching for clusters in tourism. A quantitative methodological proposal

The tourism industry is one of Europe’s leading employers, and for many regions highly dependent on tourists’ spending, innovation is the difference between growth and stagnation. Thus, at a regional level, tourism may function as a driving force of socioeconomic development and thus contribute to the demise of regional disparities. Such lever effect is usually associated to a geographical concentration abusively denominated of clusters. Most of the studies within the tourism industry identify clusters resorting to simplistic analyses of geographic location measures or experts’ opinions. These latter tend to neglect the essence of the cluster concept, namely the inter-linkages among regional actors. In the present paper, we propose a methodology to rigorously identify tourism clusters, stressing the importance of networks and cooperation between agents.Clusters; Tourism; Methodology

A General Model of Opinion Dynamics with Tunable Sensitivity

We introduce a general model of continuous-time opinion dynamics for an arbitrary number of agents that communicate over a network and form real-valued opinions about an arbitrary number of options. Drawing inspiration from models in biology, physics, and social psychology, we apply a sigmoidal saturating function to inter-agent and intra-agent exchanges of opinions. The saturating function is the only nonlinearity in the model, yet we prove how it yields rapid and reliable formation of consensus, dissensus, and opinion cascades as a function of just a few parameters. We further show how the network opinion dynamics exhibit both robustness to disturbance and ultrasensitivity to inputs. We design feedback dynamics for system parameters that enable active tuning of implicit thresholds in opinion formation for sensitivity to inputs, robustness to changes in input, opinion cascades, and flexible transitions between consensus and dissensus. The general model can be used for systematic control design in a range of engineering problems including network systems, multi-robot coordination, task allocation, and decision making for spatial navigation. It can also be used for systematic examination of questions in biology and social science ranging from cognitive control and networks in the brain, to resilience in collective animal behavior to changing environmental conditions, to information spreading and political polarization in social networks