A Decomposition-based Approach of Global Norms for Hierarchical Normative Systems

Holonic Multi-Agent System (HMAS) forms a promising approach to software engineering for the modeling and development of hierarchical autonomous systems (Intelligent transportation systems, Smart city management systems, etc.). Effectively, norms concepts are well adapted to the definition of HMAS. Its can be considered as a powerful way to specify the non-functional requirements of these types of systems. Non-functional requirements can conflict with each other (for example, cost and quality, comfort and economy). One of the main challenges currently faced in HMAS research is the coherence checking of norms that specify non-functional requirements. However verification approaches are limited by the state-space of the system under study. Specifying and verifying a global normative model in a single level is then complex and difficult. However, most normative models for multi-agent systems do not take into account the complexity of coherence verification algorithms of norms. One of solutions is to employ the use of coherent refinement process of global norms. This paper proposes a Global Norms Decomposition (GND) approach for hierarchical and critical autonomous systems. Indeed, the GND approach allows (i) the specification and verification of global norms in the abstract level of the studied system, and (ii) the successive refinement of these norms using a set of refinement rules that preserve properties of the system already proven in the highest level, in order to arrive finally at a concrete normative context which constitutes the behaviour model of the system. The GND approach allows the simplification of specification of norms, for an incremental specification using a refinement process, and the reduction of complexity of checking the coherence of norms, building verification using refinement rules. Our approach is also illustrated by a case study describing smart city management system.