Ontological aspects of the implementation of norms in agent-based electronic institutions

In order to regulate different circumstances over an extensive period of time, norms in institutions are stated in a vague and often ambiguous manner, thereby abstracting from concrete aspects which become instead relevant for the actual functioning of the institutions. If agent-based electronic institutions, which adhere to a set of abstract requirements, are to be built, how can those requirements be translated into more concrete constraints, the impact of which can be described directly in the institution? We address this issue considering institutions as normative systems based on articulate ontologies of the agent domain they regulate. Ontologies, we hold, are used by institutions to relate the abstract concepts in which their norms are formulated, to their concrete application domain. In this view, different institutions can implement the same set of norms in different ways as far as they presuppose divergent ontologies of the concepts in which that set of norms is formulated. In this paper we analyse this phenomenon introducing a notion of contextual ontology. We will focus on the formal machinery necessary to characterise it as well.