The Emergence of Symbiotic Groups Resulting From Skill-Differentiation and Tags (NetLogo version). This model is describe in:
Edmonds, B. (2006) The Emergence of Symbiotic Groups Resulting From Skill-Differentiation and Tags. Journal of Artificial Societies and Social Simulation, 9(1). (http://jasss.soc.surrey.ac.uk/9/1/10.html)