Facultad de Minas Doctorado en Ingeniería – Sistemas e Informática The Tragedy of the Commons in Artisanal Gold Mining: Evaluation of Mechanisms of Cooperation with Simulation and Economic Experiments Carlos Adrián Saldarriaga Isaza This thesis is presented to Universidad Nacional de Colombia – Sede Medellín, in partial fulfillment of the requirements for the degree of Doctor of Engineering Supervisors Santiago Arango Aramburo Associate Professor Dept. of Computing and Decision Sciences Universidad Nacional de Colombia-Sede Medellín Clara Inés Villegas Palacio Associate Professor Dept. of Geosciences and the Environment Universidad Nacional de Colombia-Sede Medellín September 2013