Promoting the evolution of cooperation in social dilemma games using contingent mobility strategies

Researchers in many domains use social dilemmas to explore the conditions necessary for cooperation to emerge among groups. Social dilemmas, and in particular the Prisoner’s Dilemma, are used because of their usefulness in capturing the conflict that exists between individually rational decisions and those made to benefit the common good. Evolutionary game theory provides a shared mathematical framework to interpret the evolution of cooperation. Contingent mobility is strategically driven, purposeful movement that is traditionally achieved through heuristically designed agent strategies or through highly restrictive globally defined conditions. Evolutionary computation techniques are used to develop contingent mobility strategies to promote cooperation without centralised control or costly memories in the Prisoner’s Dilemma game. The evolution of cooperation is promoted by contingent mobility strategies if the strategies facilitate the formation of spatially contiguous clusters of cooperative agents. This thesis presents a mobility model that allows cooperators to proactively maintain and grow these spatial structures, which they need in order to become highly fit and, ultimately, survive. A number of cluster metrics are proposed to both quantitatively and qualitatively measure the growth of these cooperative clusters. A range of evolutionary and environmental settings are investigated, and their effects on the co-evolution of cooperation and mobility are analysed. Variations in population density, agent lifespan, and the birth-death update rule are compared in terms of the levels of cooperation and the evolved mobility strategies they produced. An N-Player extension of the Prisoner’s Dilemma is considered to measure the performance of these contingent strategies in more challenging games. Results from a variety of experiments show that emergent contingent mobility strategies promote cooperation using pure game strategies in the Prisoner’s Dilemma. In particular, in a wide range of settings Follow-Flee, a strategy proposed and evolved in this work, has been shown to out compete other contemporary mobility strategies, and furthermore, practically guarantee the evolution of cooperation