Bringing Action Language C+ to Normative Contexts: Preliminary Report Dario Garcia-Gasulla and Juan Carlos Nieves Knowledge Engineering and Machine Learning Group Universitat Polit` ecnica de Catalunya C/Jordi Girona 1-3, K2M-201, Barcelona, Spain Email: {dariog, jcnieves}@lsi.upc.edu Abstract. C+ is an action language for specifying and reasoning about the effects of actions and the persistence of facts over time. Based on it we present CN+, an operational enhanced form of C+ designed for rep- resenting complex normative systems and integrate them easily into the semantics of the causal theory of actions. The proposed system contains a particular formalization of norms using a life-cycle approach to cap- ture the whole normative meaning of a complex normative framework. We discuss this approach and illustrate it with examples. Key words: Action specification languages, Norm-based systems, Causal logic (C+) 1 Introduction All real world domains are subject at some level to norms, be them physics, legal or social. Generically, norms define the socially accepted behavior within a society. They are an essential part of any domain, since all behavior within a domain is tied to its norms. In order to represent realistically any domain it is therefore necessary to specify those norms with the same level of detail used for the rest of the domain. Moreover, to achieve functionality norms must be specified using the same terms used to define the domain those norms regulate. C+[6] is an action language based on nonmonotonic causal logic. It is based on the Principle of Universal Causation (PUC) and uses causal rules to define the behavior of a domain. Several attempts have been done to extend C+ in order to allow the representation of norms in it [3], [4]. Those attempts opened the path to norm formalization in C+, but did not provide an explicit syntax for expressing the singularities of normative contexts. In order to produce the tools required for complex normative monitoring and reasoning, we must be able to represent more information than just the current legal state (legal, ilegal) given a normative framework. To produce operational solutions we must also be able to know the exact status of each norm (applicable, respected) in a given situation and how every action will affect the internal status of each norm. A system will perform better knowing which norms is it subject to and which norms is it violating by performing actions which respect the norms 89