This paper presents an argument that the process of emergence, moving from simple rules to complex behavior, is the converse of the process of abstraction, moving from complex behavior to simple laws. Thus, it can be argued that similar mechanisms underlie both processes, and a greater understand of one can lead to a greater understanding of the other. Especially in the case of societies, the processes of abstraction and emergence are inextricably interconnected, such that the abstractions individuals make will determine what behaviors emerge, and the behaviors that emerge in the society determine what abstractions will be made. In addition to describing this abstraction-emergence loop, the paper offers a description of an ongoing research project aimed at exploring and understanding the nature of this loop and the emergence to which it leads. Such an understanding of the relationship between abstraction and emergence can be helpful in designing communities of autonomous agents that interact socially with each other and with humans.

In cooperative multi-agent systems, roles are used as a design concept when creating large systems, they are known to facilitate specialization of agents, and they can help to reduce interference in multi-robot domains. The types of tasks that the agents are asked to solve and the communicative capabilities of the agents significantly affect the way roles are used in cooperative multi-agent systems. Along with a discussion of these issues about roles in multi-agent systems, this article compares computational models of the role allocation problem, presents the notion of explicitly versus implicitly defined roles, gives a survey of the methods used to approach role allocation problems, and concludes with a list of open research questions related to roles in multi-agent systems.