Open systems are characterized by heterogeneous participants which can enter or leave the system at will. Typical examples are e-commerce applications or information agent systems. Agents (e.g. personal assistants for buying things on the Internet) will only temporarily take up roles (e.g. a buyer in on-line auctions). This creates the need to define precisely what it means that an agent "takes up" a role and "enacts" it. In this paper we present ongoing research on the determination of the conditions under which an agent can enact a role and what it means for the agent to enact a role. We define possible relations between roles and agents and discuss architectural and functional changes that an agent must undergo when it enters an open agent system.

Despite all the research done in the last years on the development of methodologies for designing MAS, there is no methodology suitable for the specification and design of MAS in complex domains where both the agent view and the organizational view can be modelled. Current multi-agent approaches either take a centralist, static approach to organizational design or take an emergent view in which agent interactions are not pre determined, thus making it impossible to make any predictions on the behavior of the whole systems. Most of them also lack a model of the norms in the environment that should rule the (emergent) behavior of the agent society as a whole and/or the actions of individuals. In this paper, we propose a framework for modelling agent organizations, Omni , that allows the balance of global organizational requirements with the autonomy of individual agents. It specifies

In this paper, we propose a framework for modelling agent organizations, Omni, that allows the balance of global organizational requirements with the autonomy of individual agents. It specifies global goals of the system independently from those of the specific agents that populate the system. Both the norms that regulate interaction between agents, as well as the contextual meaning of those interactions are important aspects when specifying the organizational structure. Omni integrates all this aspects in one framework. In order to make design of the multi-agent system manageable, we distinguish three levels of abstraction with increasing implementation detail. All dimensions of Omni have a formal logical semantics, which ensures consistency and possibility of verification of the different aspects of the system. Omni is therefore utmost suitable for the modelling of all types of MASfromopentoclosedenvironments. 1.

Abstract — Contracts are used to create new interaction possibilities among agents, and they therefore play an important role in the game theoretic analysis of agent interaction. We use normative multiagent systems to model both the contracts and the interactions. In particular, we formalize contracts as systems of regulative and constitutive norms within a larger rule-governed setting, and using recursive modelling we develop a game theory where agents make contracts. We show how agents can modify the behavior of normative systems by means of constitutive rules in the contract changing these systems, and we illustrate how agents use the game theory within contract negotiation in organizations. Index Terms — Contracts, qualitative game theory, multiagent systems, normative systems.

Abstract. The European Commission’s eEurope initiative aims to bring every citizen, home, school, business and administration online to create a digitally literate Europe. The value lies not in the objective itself, but in its ability to facilitate the advance of Europe into new ways of living and working. Just as in the first literacy revolution, our lives will change in ways never imagined. The vision of eEurope is underpinned by a technological infrastructure that is now taken for granted. Yet it provides us with the ability to pioneer radical new ways of doing business, of undertaking science, and, of managing our everyday activities. Key to this step change is the development of appropriate mechanisms to automate and improve existing tasks, to anticipate desired actions on our behalf (as human users) and to undertake them, while at the same time enabling us to stay involved and retain as much control as required. For many, these mechanisms are now being realised by agent technologies, which are already providing dramatic and sustained benefits in several business and industry domains, including B2B exchanges, supply chain management, car manufacturing, and so on. While there are many real successes of agent technologies to report, there is still much to be done in research and development for the full benefits to be achieved. This is especially true in the context of environments of pervasive computing devices that are envisaged in coming years. This paper describes the current state-of-the-art of agent technologies and

In the paper we study the dynamics of roles played by agents in multiagent systems. We capture role dynamics in terms of four operation performed by agents: `enactment', `deactment', `activate', and `deactivate'. The use of these operations are motivated, in particular for open systems. A formal semantics for these operations are provided. This formalization is aimed at serving as a basis for implementation of role dynamics in an agent programming language such as 3APL.

Abstract. Prototyping is a valuable technique to help software engineers explore the design space while gaining insight on the dynamics of the system. In this paper, we describe a method for rapidly building prototypes of large multi-agent systems using logic programming. Our method advocates the use of a description of all permitted interactions among the components of the system, that is, the protocol, as the starting specification. The protocol is represented in a way that allows us to automatically check for desirable properties of the system to be built. We then employ the same specification to synthesise agents that will correctly follow the protocol. These synthesised agents are simple logic programs that engineers can further customise into more sophisticated software. Our choice of agents as logic programs allows us to provide semi-automatic support for the customisation activity. In our method, a prototype is a protocol with a set of synthesised and customised agents. Executing the prototype amounts to having these agents enact the protocol. We have implemented and described a distributed platform to simulate prototypes. 1.

Abstract. We propose a logic-based rendition of electronic institutions – these are means to specify open agent organisations. We employ a simple notation based on first-order logic and set theory to represent an expressive class of electronic institutions. We also provide a formal semantics for our constructs and present a distributed implementation of a platform to enact electronic institutions specified in our formalism. 1

The use of multi-agent systems (MAS) in health-care domains is increasing. Such agent-mediated medical systems can manage complex tasks and have the potential to adapt gracefully to unexpected events. However, in these kinds of systems the issues of privacy, security and trust are particularly sensitive in relation to matters such as agents' access to patient records, what is acceptable behaviour for an agent in a particular role and the development of trust both between (heterogeneous) agents and between users and agents. To address

We present the MOdel of Organisational Change using Agents (MOCHA) as a means to formally specify, check and simulate organisations and their changes using agents. We define the structure of the organisation without making any assumptions about the internal characteristics of the agents who will populate it. We adopt a normative view of organisations, and capture a notion of social influence through relationships between roles. Ours is a flexible and expressive approach that contemplates agents taking part in multiple organisations with distinct roles and disparate (possibly conflicting) obligations. We make a distinction between the structure of an organisation and the population instantiating the organisation, and our framework allows the consequences of change in both the organisational structure and the population to be investigated. We also describe a machine-processable representation of our model and show how it can be used to support engineering activities. 1