The specification of open interaction systems, which may be dynamically entered and left by autonomous agents, is widely recognized to be a crucial issue in the development of distributed applications on the internet. The specification of such systems involves two main problems: the first is the definition of a standard way of specifying a communication language for the interacting agents and the context of the interaction; the second, which derives from the assumption of the agents' autonomy, is finding a way to regulate interactions so that agents may have reliable expectations on the future development of the system. A possible approach to solve those problems consists in modelling the interaction systems as a set of artificial institutions. In this chapter we address this issue by formally defining, in the Event Calculus, a repertoire of abstract concepts (like commitment, institutional power, role, norm) that can be used to specify artificial institutions. We then show how, starting from the formal specification of a system and using a suitable tool, it is possible to simulate and monitor the systems evolution through automatic deduction
