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In this paper we argue that the hypothesis of the theory of mind advanced in cognitive science can be the basis not only of the social abilities which allow interaction among individuals, but also of the construction of social reality. The theory of mind is the attribution, via the agent metaphor, of mental attitudes, like beliefs and goals, to other agents. Analogously, we attribute mental attitudes to social entities, like groups, normative systems and organizations with roles. The agent metaphor explains the necessary abilities to deal with complex aspects of social behavior, like acting in a group, playing a role in an organization, and living in a reality organized in institutions which create regulative and constitutive norms to regulate behavior. To show the feasibility of this approach we provide a computational model of the construction of social reality based on multiagent systems.

In this paper we use normative systems to introduce roles and rights in the game-theoretic artificial social systems developed by Shoham and Tennenholtz. We model normative systems as socially constructed agents whose behavior is determined by a set of role playing agents. Roles are again modeled as socially constructed agents, and the rolesý behavior is the ideal behavior of agents playing the roles. In our approach, the strategies of the role correspond to the rights that can be exercised by the role. In other words, rights are powers extending the set of strategies of an agent - not constraining them! - due to the new opportunities to exercise rights. We consider the role assignment problem of how to assign agents to roles such that the role playing agent is expected to behave like the ideal behavior of the role. We also consider how the normative system controls the behavior of agents playing a role in it.

We study the design of policies for virtual communities of agents based on peer-to-peer systems or the grid infrastructure. In a virtual community agents can play both the role of resource consumers and the role of resource providers. Moreover, the agents remain in control of their resources, and therefore we distinguish between the authorization to access a resource given by the virtual community and the permission to do so issued by the resource providers. We propose a logical multiagent framework for virtual communities that distinguishes three roles: resource consumption, provision, as well as authorization.

There are two main traditions in defining a semantics for agent communication languages, based either on mental attitudes or on social commitments. In this paper we show how the role metaphor can be used to bridge the gap between these two approaches. First, we show how dialogues can be modelled as games - a form of normative systems - and how mental attitudes can be attributed not only to agents, but also, in a public manner, to the roles of the game. The dialogue moves allow an agent playing a role to modify the rolesý mental states, as specified by the counts-as conditionals (also known as constitutive norms) defining the game. The player of a role is expected to act as if it has the mental attitudes attributed to its role during the dialogue and to prevent its roleýs mental attitudes from becoming incoherent, as it does for its own private mental attitudes. Secondly, we show how roles as descriptions of expected behavior maintain the normative character of social semantics. Due to the bridge between the two approaches, results and tools from one approach can be used in the other one.

In this paper we use recursive modelling to formalize sanction-based obligations in a qualitative game theory. In particular, we formalize an agent who attributes mental attitudes such as goals and desires to the normative system which creates and enforces its obligations. The wishes (goals, desires) of the normative system are the commands (obligations) of the agent. Since the agent is able to reason about the normative system’s behavior, our model accounts for many ways in which an agent can violate a norm believing that it will not be sanctioned. We thus propose a cognitive theory of normative reasoning which can be applied in theories requiring dynamic trust to understand when it is necessary to revise it.

We are interested in interactive access control to web services in virtual organizations. We discuss argument games in which the set of credentials requested by the service provider to access a service is established by means of an interaction between a client acting as a proponent and a server acting as an opponent.

We study admissible coalitions in goal-directed multiagent systems.We define a qualitative criterion of admissibility in which a coalition has itself all the necessary information to check admissibility. We show also that, under some assumptions on preference relations of the agents, this admissibility criterion can be used to reduce the search space in a game theoretical approach.

In this paper we study the enforcement of social laws in artificial social systems using a control system. We define the enforceable social law problem as an extension of Tennenholtz' stable social law problem. We distinguish the choice of social laws from the choice of control systems, where the latter leads to new computational problems. We consider also properties of sanction based control systems, and monitoring when there is no full observability.

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.

There are two main traditions in defining a semantics for agent communication languages, based either on mental attitudes or on social commitments. In this paper we show how the role metaphor can be used to bridge the gap between these two approaches. First, we show how dialogues can be modelled as games - a form of normative systems - and how mental attitudes can be attributed not only to agents, but also, in a public manner, to the roles of the game. The dialogue moves allow an agent playing a role to modify the rolesý mental states, as specified by the counts-as conditionals (also known as constitutive norms) defining the game. The player of a role is expected to act as if it has the mental attitudes attributed to its role during the dialogue and to prevent its roleýs mental attitudes from becoming incoherent, as it does for its own private mental attitudes. Secondly, we show how roles as descriptions of expected behavior maintain the normative character of social semantics. Due to the bridge between the two approaches, results and tools from one approach can be used in the other one.

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.

In this paper we argue that the hypothesis of the theory of mind advanced in cognitive science can be the basis not only of the social abilities which allow interaction among individuals, but also of the construction of social reality. The theory of mind is the attribution, via the agent metaphor, of mental attitudes, like beliefs and goals, to other agents. Analogously, we attribute mental attitudes to social entities, like groups, normative systems and organizations with roles. The agent metaphor explains the necessary abilities to deal with complex aspects of social behavior, like acting in a group, playing a role in an organization, and living in a reality organized in institutions which create regulative and constitutive norms to regulate behavior. To show the feasibility of this approach we provide a computational model of the construction of social reality based on multiagent systems.

We study admissible coalitions in goal-directed multiagent systems.We define a qualitative criterion of admissibility in which a coalition has itself all the necessary information to check admissibility. We show also that, under some assumptions on preference relations of the agents, this admissibility criterion can be used to reduce the search space in a game theoretical approach.

We study the design of policies for virtual communities of agents based on peer-to-peer systems or the grid infrastructure. In a virtual community agents can play both the role of resource consumers and the role of resource providers. Moreover, the agents remain in control of their resources, and therefore we distinguish between the authorization to access a resource given by the virtual community and the permission to do so issued by the resource providers. We propose a logical multiagent framework for virtual communities that distinguishes three roles: resource consumption, provision, as well as authorization.

We are interested in interactive access control to web services in virtual organizations. We discuss argument games in which the set of credentials requested by the service provider to access a service is established by means of an interaction between a client acting as a proponent and a server acting as an opponent.

In this paper we use normative systems to introduce roles and rights in the game-theoretic artificial social systems developed by Shoham and Tennenholtz. We model normative systems as socially constructed agents whose behavior is determined by a set of role playing agents. Roles are again modeled as socially constructed agents, and the rolesý behavior is the ideal behavior of agents playing the roles. In our approach, the strategies of the role correspond to the rights that can be exercised by the role. In other words, rights are powers extending the set of strategies of an agent - not constraining them! - due to the new opportunities to exercise rights. We consider the role assignment problem of how to assign agents to roles such that the role playing agent is expected to behave like the ideal behavior of the role. We also consider how the normative system controls the behavior of agents playing a role in it.

In this paper we use recursive modelling to formalize sanction-based obligations in a qualitative game theory. In particular, we formalize an agent who attributes mental attitudes such as goals and desires to the normative system which creates and enforces its obligations. The wishes (goals, desires) of the normative system are the commands (obligations) of the agent. Since the agent is able to reason about the normative system’s behavior, our model accounts for many ways in which an agent can violate a norm believing that it will not be sanctioned. We thus propose a cognitive theory of normative reasoning which can be applied in theories requiring dynamic trust to understand when it is necessary to revise it.

In this paper we study the enforcement of social laws in artificial social systems using a control system. We define the enforceable social law problem as an extension of Tennenholtz' stable social law problem. We distinguish the choice of social laws from the choice of control systems, where the latter leads to new computational problems. We consider also properties of sanction based control systems, and monitoring when there is no full observability.

In this paper we study the distribution of obligations together with their associated sanctions among agents belonging to collective entities like groups and organizations. We model the distribution as a negotiation process among the agents, we model the behavior of the agents in a qualitative game theory, and we formalize them in a logical framework. We characterize collective obligations according to the way the responsibility in case of violation is attributed to individual agents or to the whole set of agents, where we distinguish among violations during the negotiation and during the execution of the task. We also show that in some cases it is a drawback to be the only agent able to see to the fulfilment of part of an obligation, but in other cases it may be an advantage, because of the power it gives to the agent during the negotiation.

In this paper we study the distribution of obligations together with their associated sanctions among agents belonging to collective entities like groups and organizations. We model the distribution as a negotiation process among the agents, we model the behavior of the agents in a qualitative game theory, and we formalize them in a logical framework. We characterize collective obligations according to the way the responsibility in case of violation is attributed to individual agents or to the whole set of agents, where we distinguish among violations during the negotiation and during the execution of the task. We also show that in some cases it is a drawback to be the only agent able to see to the fulfilment of part of an obligation, but in other cases it may be an advantage, because of the power it gives to the agent during the negotiation.