Analysis and Control of Strategic Interactions in Finite Heterogeneous Populations under Best-Response Update Rule

For a finite, well-mixed population of heterogeneous agents playing evolutionary games choosing to cooperate or defect in each round of the game, we investigate, when agents update their strategies in each round using the myopic best-response rule, how the number of cooperating agents changes over time and demonstrate how to control that number by changing the agents’ payoff matrices. The agents are heterogeneous in that their payoff matrices may differ from one another; we focus on the specific case when the payoff matrices, fixed throughout the evolution, correspond to prisoner’s dilemma or snowdrift games. To carry out stability analysis, we identify the system’s absorbing states when taking the number of cooperating agents as a random variable of interest. It is proven that when all the agents update frequently enough, the reachable final states are completely determined by the available types of payoff matrices. As a further step, we show how to control the final state by changing at the beginning of the evolution, the types of the payoff matrices of a group of agents

How feeling betrayed affects cooperation

For a population of interacting self-interested agents, we study how the average cooperation level is affected by some individuals' feelings of being betrayed and guilt. We quantify these feelings as adjusted payoffs in asymmetric games, where for different emotions, the payoff matrix takes the structure of that of either a prisoner's dilemma or a snowdrift game. Then we analyze the evolution of cooperation in a well-mixed population of agents, each of whom is associated with such a payoff matrix. At each time-step, an agent is randomly chosen from the population to update her strategy based on the myopic best-response update rule. According to the simulations, decreasing the feeling of being betrayed in a portion of agents does not necessarily increase the level of cooperation in the population. However, this resistance of the population against low-betrayal-level agents is effective only up to some extend that is explicitly determined by the payoff matrices and the number of agents associated with these matrices. Two other models are also considered where the betrayal factor of an agent fluctuates as a function of the number of cooperators and defectors that she encounters. Unstable behaviors are observed for the level of cooperation in these cases; however, we show that one can tune the parameters in the function to make the whole population become cooperative or defective

Whose line is it anyway? Understanding the military role in delivering rights based policies in post-conflict territories

The post-conflict territories of the Western Balkans have been subjected to an unprecedented level of international attention since the mid-1990s. The EU, NATO and OSCE in particular converged on the region intent on redefining their image - if not purpose - in the first major crisis of the post-Cold War era. Responding to the horrific inter-ethnic violence that defined conflict in the region, International Organisations continually emphasised the importance of upholding standards regarding the protection of, and respect for, ethnic minorities. While literature acknowledges that military forces were deployed to establish and maintain a safe and secure environment for post-conflict peacebuilding to emerge, few scholars have explored the substance of the military role beyond the separation of former warring factions and provision of a secure humanitarian space. This research demonstrates that military actors adapted their approaches to contribute across the spectrum of the peacebuilding effort, including on rights based issues; specifically ethnic minority returns and participation. On the basis of case studies in Kosovo and Bosnia Herzegovina, the thesis adopts an empirical approach to exploring the reasons for military engagement on these issues and their respective successes and failures. It examines the sources that projected ideas on ethnic minority issues – international policy development, peace treaty composition, and domestic acceptance – and how they influenced military decision making processes. Through post-conflict phases it analyses the domestic footprint of international intervention – international administration and civil-military actors – and discusses thematically the means of military engagement, the receptiveness of domestic actors at multiple levels and the nature of compliance. Acknowledging the overarching civilian framework for intervention, where from the outset the prospective of NATO and EU membership were held forth as the 'prize' for a successful return to 'a Europe of integration, democracy and ethnic pluralism', it establishes the utility of strategic mechanisms – conditionality and normative pressure – in military hands acknowledging the potential for linkage to enlargement frameworks. It argues that in spite of principled objections, military operations can and do have influence in delivering policy on rights based issues