Norm Defeasibility in an Institutional Normative Framework

Normative environments have been proposed to regulate agent interaction in open multi-agent systems. However, most approaches rely on pre-imposed regulations that agents are subject to. Taking a different stance, we focus on a normative framework that assists agents in establishing by themselves their own commitment norms. With that aim in mind, a model of norm defeasibility is presented that enables exploiting and adapting a normative background to different extents. We formalize the normative state using first-order logic and define rules and norms operating on that state. A suitable semantics regarding the use of norms within a hierarchical context structure is given, based on norm activation conflict and defeasibility.