Abstract. In this paper we propose a new role for the agent metaphor in the definition of the organizational structure of multiagent systems. The agent metaphor is extended to consider as agents also social entities like organizations, groups and normative systems, so that mental attitudes can be attributed to them- beliefs, desires and goals- and also an autonomous and proactive behavior. We show how the metaphor can be applied also to structure organizations in functional areas and roles, which are described as agents too. Thus, the agent metaphor can play a role similar to the object oriented metaphor which allows structuring objects in component objects. Finally, we discuss how the agent metaphor addresses the problems of control and communication in such structured organizations. 1

Abstract. In this paper we introduce an ontology based on the notion of agent to represent and reason about social reality. We model social constructions as agents, for example, groups, organizations, normative systems, and roles, and we attribute mental attitudes to them. Roughly, we define obligations or regulative norms as goals of the normative system, constitutive norms as beliefs of the normative system, joint, shared, mutual and social beliefs, desires and goal as beliefs, desires and goals of group, responsibilities of an agent as goals of the role he plays, and the required expertise of an agent as beliefs and actions of the role he plays. In this way, we achieve a uniform framework for a large variety of concepts using a small vocabulary, and, in particular, basing it on notions, like mental attitudes, which are commonly used in agent theories. The proposed ontology is modelled using a description logic. 1

Abstract. Social roles structure social institutions like organizations in Multi-Agent Systems (MAS). In this paper we describe how to introduce the notion of social role in programming languages. To avoid the commitment to a particular agent model, architecture or language, we decided to extend Java, the most prominent object oriented programming language, by adding social roles. The obtained language allows an easier implementation of MAS’s w.r.t. the Java language. We also show that many important properties of social roles, studied in the MAS field, can be applied to objects. Two are the essential features of social roles according to an analysis reported in the paper: social roles are defined by other entities (called institutions), and when an agent plays a role it is endowed with powers by the institution that defines it. We interpret these two features into the object oriented paradigm as the fact that social roles are objects, which are defined in and exist only inside other objects (corresponding to institutions), and that, through a role, external objects playing the role can access to the object (institution) the role belongs to. 1

In this paper we apply the role metaphor to coordination. Roles are used in sociology as a way for structuring organizations and for coordinating their behavior. In our model, the distinguishing features of roles are their dependence on an institution, and the powers they assign to the players of roles. The institution represents an environment where the different components interact with each other by using the powers attributed to them by the roles they play, even when they do not know each other. The interaction between a component playing a role and the role is performed via precise interfaces stating the requirements to play a role, and which powers are attributed by roles. Roles encapsulate their players ’ capabilities to interact with the institution and with the other roles, thus achieving separation of concerns between computation and coordination. The institution acts as a coordinator which manages the interactions among components by acting on the roles they play, thus achieving a form of exogenous coordination. As an example, we introduce the role construct in the Java programming language, providing a precompiler for it. In order to better explain the proposal, we show how to use the role construct as a coordination means by applying it to a dining philosophers problem extended with dynamic reconfiguration. 1

Abstract. We explain the raison d’être and basic ideas of our gametheoretic approach to normative multiagent systems, sketching the central elements with pointers to other publications for detailed developments.

We are interested in the design of policies for virtual communities of agents based on the grid infrastructure. In a virtual community agents can play both the role of resource consumers and the role of resource providers, and they remain in control of their resources. We argue that this requirement creates a distinction between two dimensions: global vs local and centralized and decentralized control by means of policies. The providers should be enabled to specify their local policies on their own resources, but their policies should be consistent with the global policies. At the same time, some aspects of the decentralized control should be delegated to specialized providers; this delegation requires a distinction between the authorization to access a resource and a permission to do so. 1

Coordination languages and models like Linda and Reo have been developed in computer science to coordinate the interaction among components and objects, and are nowadays used to model and analyze organizations too. Moreover, organizational concepts are used to enrich the existing coordination languages and models. We describe this research area of “organization and coordination ” by presenting definitions, examples, and future research directions. We highlight two issues. First, we argue for a study of value-based rather than information-based coordination languages to model the coordination of autonomous agents and organizations. Second, we argue for a study of the balance between enforced control and trust-based anticipation to deal with security aspects in the coordination of organizations.

Abstract. This paper begins with the comparison of the messagesending mechanism, for communication among agents, and the methodinvocation mechanism, for communication among objects. Then, we describe an extension of the method-invocation mechanism by introducing the notion of “sender ” of a message, “state ” of the interaction and “protocol ” using the notion of “role”, as it has been introduced in the powerJava extension of Java. The use of roles in communication is shown by means of an example of protocol. 1

Abstract. In this paper, we propose a model of constitutive and regulative norms in a logical multiagent framework. We analyze the relationship between these two types of rules and explain similarities between them, using the metaphor of considering social entities- like normative systems, groups and organizations- as agents and of attributing them mental attitudes as well as an autonomous behavior. We argue that while constitutive norms expressing “counts-as ” relations are modelled as the beliefs of social entities, regulative norms, like obligations, prohibitions and permissions, are modelled as their goals. 1