Making Consensus Tractable

We study a model of consensus decision making, in which a finite group of Bayesian agents has to choose between one of two courses of action. Each member of the group has a private and independent signal at his or her disposal, giving some indication as to which action is optimal. To come to a common decision, the participants perform repeated rounds of voting. In each round, each agent casts a vote in favor of one of the two courses of action, reflecting his or her current belief, and observes the votes of the rest. We provide an efficient algorithm for the calculation the agents have to perform, and show that consensus is always reached and that the probability of reaching a wrong decision decays exponentially with the number of agents.Comment: 18 pages. To appear in Transactions on Economics and Computatio

Increasing environmental sustainability by incorporating stakeholders' intensities of preferences into the policy formation

In this paper a tractable methodology is presented to improve environmental sustainability by incorporating stakeholders’ intensities of preferences into the decision making process. The environmental decision making will be controversial when there is a complex issue at hand. The difficulty comes up as stakeholders cannot see how their preferences are taken into account in the policy making process. To reduce this controversy, we propose a qualitative method to elicit stakeholders’ intensities of preferences towards a set of environmental services. Subsequently, the elicited intensities of preferences are aggregated by a mathematical approach on each single criterion. Finally, a multi-criteria approach is applied to use the aggregated values across all criteria to provide the analyst with a rank order of existing alternative plans. In this way, the stakeholders are able to verify that their opinion is taken into account, even if it is contrary to the majority voice. The natural resources manager will benefit from an increased insight into the prevalent opinion on each of the criteria through the supplied social intensities of preferences, enabling a more easily communicated justification of the final decision, and an augmented tractability of the decision making process.Sustainability, stakeholder's preferences, tractable decision making, social support, qualitative valuation, Environmental Economics and Policy,

Adaptive Network Dynamics and Evolution of Leadership in Collective Migration

The evolution of leadership in migratory populations depends not only on costs and benefits of leadership investments but also on the opportunities for individuals to rely on cues from others through social interactions. We derive an analytically tractable adaptive dynamic network model of collective migration with fast timescale migration dynamics and slow timescale adaptive dynamics of individual leadership investment and social interaction. For large populations, our analysis of bifurcations with respect to investment cost explains the observed hysteretic effect associated with recovery of migration in fragmented environments. Further, we show a minimum connectivity threshold above which there is evolutionary branching into leader and follower populations. For small populations, we show how the topology of the underlying social interaction network influences the emergence and location of leaders in the adaptive system. Our model and analysis can describe other adaptive network dynamics involving collective tracking or collective learning of a noisy, unknown signal, and likewise can inform the design of robotic networks where agents use decentralized strategies that balance direct environmental measurements with agent interactions.Comment: Submitted to Physica D: Nonlinear Phenomen