Adding Organizations and Roles as Primitives to JADE Framework

in Proceedings of the 3rd International Workshop on Normative Multiagent Systems, NorMAS'08 (2008)

The organization metaphor is often used in the design and implementation of multiagent systems. However, few agent programming languages provide facilities to define them. Several frameworks are proposed ... [more ▼]

The organization metaphor is often used in the design and implementation of multiagent systems. However, few agent programming languages provide facilities to define them. Several frameworks are proposed to coordinate MAS with organizations, but they are not programmable with general purpose languages. In this paper we extend the JADE framework with primitives to program in Java organizations structured in roles and to enable agents to play roles in organizations. Roles facilitate the coordination of agents inside an organization and give new abilities in the context of organizations, called powers, to the agents which satisfy the requirements necessary to play the roles. As primitives to program organizations and roles we provide classes and protocols which enable an agent to enact a new role in an organization and to interact with the role by invoking the execution of powers, and to receive new goals to be fulfilled. Roles have state and behaviour, thus, they are instances of classes and are strictly connected with the organization offering them. Since roles and organizations can be on a different platform with respect to the role player, the communication with them happens via protocols. Moreover, since, besides using protocols, roles and organizations can have complex behaviours, they are implemented by extending the JADE agent class. [less ▲]

Reasoning With Various Kinds of Preferences: Logic, Non-Monotonicity, and Algorithms

in Annals of Operations Research (2008), 163(1), 89114

As systems dealing with preferences become more sophisticated, it becomes essential to deal with various kinds of preference statements and their interaction. We introduce a non-monotonic logic ... [more ▼]

As systems dealing with preferences become more sophisticated, it becomes essential to deal with various kinds of preference statements and their interaction. We introduce a non-monotonic logic distinguishing sixteen kinds of preferences, ranging from strict to loose and from careful to opportunistic, and two kinds of ways to deal with uncertainty, either optimistically or pessimistically. The classification of the various kinds of preferences is inspired by a hypothetical agent comparing the two alternatives of a preference statement. The optimistic and pessimistic way of dealing with uncertainty correspond on the one hand to considering either the best or the worst states in the comparison of the two alternatives of a preference statement, and on the other hand to the calculation of least or most specific “distinguished” preference orders from a set of preference statements. We show that each way to calculate distinguished preference orders is compatible with eight kinds of preferences, in the sense that it calculates a unique distinguished preference order for a set of such preference statements, and we provide efficient algorithms that calculate these unique distinguished preference orders. In general, optimistic kinds of preferences are compatible with optimism in calculating distinguished preference orders, and pessimistic kinds of preferences are compatible with pessimism in calculating distinguished preference orders. However, these two sets of eight kinds of preferences are not exclusive, such that some kinds of preferences can be used in both ways to calculate distinguished preference orders, and other kinds of preferences cannot be used in either of them. We also consider the merging of optimistically and pessimistically constructed distinguished preferences orders. [less ▲]

Formal analysis of trace conditioning

in Cognitive Systems Research (2007), 8(1), 3647

In the literature classical conditioning is usually described and analysed informally. If formalisation is used, this is often based on mathematical models based on difference or differential equations ... [more ▼]

In the literature classical conditioning is usually described and analysed informally. If formalisation is used, this is often based on mathematical models based on difference or differential equations. This paper explores a formal description and analysis of the process of trace conditioning, based on logical specification and analysis methods of dynamic properties of the process. Specific types of dynamic properties are global dynamic properties, describing properties of the process as a whole, or local dynamic properties, describing properties of basic steps in a conditioning process. If the latter type of properties are specified in an executable format, they provide a temporal declarative specification of a simulation model. By a software environment these local properties can be used to actually perform simulation. Global properties can be checked automatically for simulated or other traces. Using these methods the properties of conditioning processes informally expressed by Los and Van Den Heuvel [Los, S. A., & Van Den Heuvel, C. E. (2001). Intentional and unintentional contributions to non-specific preparation during reaction time foreperiods. Journal of Experimental Psychology: Human Perception and Performance, 27, 370–386] have been formalised and verified against a specification of local properties based on Machado’s [Machado, A. (1997). Learning the temporal dynamics of behaviour. Psychological Review, 104, 241–265] differential equation model. [less ▲]

Roles in Coordination and in Agent Deliberation: A Merger of Concepts

in Proceedings of AWESOME07 (2007)

In this paper we generalize and merge two models of roles used in multiagent systems which address complementary aspects: enacting roles and communication among roles in an organization or institution. We ... [more ▼]

In this paper we generalize and merge two models of roles used in multiagent systems which address complementary aspects: enacting roles and communication among roles in an organization or institution. We do this by proposing a metamodel of roles and specializing the metamodel to fit two existing models. We show how the two approaches can be integrated since they deal with complementary aspects: [1] focuses on roles as a way to specify interactions among agents, and, thus, it emphasizes the public character of roles. [2] focuses instead on how roles are played, and thus it emphasizes the private aspects of roles: how the beliefs and goals of the roles become the beliefs and goals of the agents. The former approach focuses on the dynamics of roles in function of the communication process. The latter approach focuses on the internal dynamics of the agents when they start playing a role or shift the role they are currently playing. [less ▲]

Norm negotiation in multiagent systems

in International Journal of Cooperative Information Systems (2007), 16(2),

Normative multiagent systems provide agents with abilities to autonomously devise societies and organizations coordinating their behavior via social norms and laws. In this paper we study how agents ... [more ▼]

Normative multiagent systems provide agents with abilities to autonomously devise societies and organizations coordinating their behavior via social norms and laws. In this paper we study how agents negotiate new social norms and when they accept them. We introduce a negotiation model based on what we call the social delegation cycle, which explains the negotiation of new social norms from agent desires in three steps. First individual agents or their representatives negotiate social goals, then a social goal is negotiated in a social norm, and finally the social norm is accepted by the agents when it leads to fulfilment of the desires the cycle started with. We characterize the allowed proposals during social goal negotiation as mergers of the individual agent desires, and we characterize the allowed proposals during norm negotiation as both joint plans to achieve the social goal (obligations associated with the norm) and the associated sanctions or rewards (a control system associated with the norm). The norm is accepted when the norm is stable in the sense that agents will act according to the norm, and effective in the sense that fulfilment of the norm leads to achievement of the agents’ desires. We also compare norm negotiation with contract negotiation and negotiation of the distribution of obligations [less ▲]

An Attacker Model for Normative Multi-agent Systems

in Multi-Agent Systems and Applications V, 5th International Central and Eastern European Conference on Multi-Agent Systems, CEEMAS 2007, Leipzig, Germany, September 25-27, 2007, Proceedings (2007)

In this paper we introduce a formal attacker model for nor- mative multi-agent systems. In this context, an attacker is an agent try- ing to profit from norm violation, for example because the violation ... [more ▼]

In this paper we introduce a formal attacker model for nor- mative multi-agent systems. In this context, an attacker is an agent try- ing to profit from norm violation, for example because the violation is not detected, it is not being sanctioned, or the sanction is less than the profit of violation. To deliberate about norm violations, an attacker has a self model and a model of the normative multi-agent system, which in our case have the same structure. Moreover, we assume that an attacker violates a norm only when it profits from it, and the attacker therefore plays a violation game with the system. On a variety of examples, we show also how our model of violation games based also on agent abilities or power extends our earlier model based on motivations only [less ▲]

Ten Philosophical Problems in Deontic Logic

in Normative Multi-agent Systems (2007)

The paper discusses ten philosophical problems in deontic logic: how to formally represent norms, when a set of norms may be termed `coherent', how to deal with normative conflicts, how contrary-to-duty ... [more ▼]

The paper discusses ten philosophical problems in deontic logic: how to formally represent norms, when a set of norms may be termed `coherent', how to deal with normative conflicts, how contrary-to-duty obligations can be appropriately modeled, how dyadic deontic operators may be redefined to relate to sets of norms instead of preference relations between possible worlds, how various concepts of permission can be accommodated, how meaning postulates and counts-as conditionals can be taken into account, and how sets of norms may be revised and merged. The problems are discussed from the viewpoint of input/output logic as developed by van der Torre Makinson. We argue that norms, not ideality, should take the central position in deontic semantics, and that a semantics that represents norms, as input/output logic does, provides helpful tools for analyzing, clarifying and solving the problems of deontic logic. [less ▲]

Contextual Agent Deliberation in Defeasible Logic

in PRIMA (2007)

This article extends Defeasible Logic to deal with the contextual de- liberation process of cognitive agents. First, we introduce meta-rules to reason with rules. Meta-rules are rules that have as a ... [more ▼]

This article extends Defeasible Logic to deal with the contextual de- liberation process of cognitive agents. First, we introduce meta-rules to reason with rules. Meta-rules are rules that have as a consequent rules for motivational components, such as obligations, intentions and desires. In other words, they in- clude nested rules. Second, we introduce explicit preferences among rules. They deal with complex structures where nested rules can be involved. [less ▲]

Reasoning About Norms, Obligations, Time and Agents

in PRIMA (2007)

Reasoning about norms and time is of central concern to the regulation or control of the behavior of a multiagent system. In this paper we introduce a representation of normative systems that ... [more ▼]

Reasoning about norms and time is of central concern to the regulation or control of the behavior of a multiagent system. In this paper we introduce a representation of normative systems that distinguishes between norms and the detached obligations of agents over time, leading to a simple and therefore practical way to reason about norms, obligations, time and agents. We consider the reasoning tasks to determine whether a norm is redundant in a normative system and whether two normative systems are equivalent. In the former case the redundant norm might be removed. In the latter case one norm might be replaced by the other. It is well known that properties concerning iterated or deontic detachment no longer hold when reasoning with multiple agents or with obligations over time. Yet, earlier approaches to reasoning about norms rarely consider the intricacies of time. We show how norms can be used to define the persistence of obligations of agents over time. We illustrate our approach by discussing three ways to relate norms and obligations of agents over time. Also we show how these three ways can be characterized. [less ▲]

A Game-Theoretic Approach to Normative Multi-Agent Systems

in Normative Multi-agent Systems (2007)

We aim to explain our own approach, and we are therefore very brief with respect to recent related approaches in the area of normative multiagent sys- tems. For these other approaches, see the special ... [more ▼]

We aim to explain our own approach, and we are therefore very brief with respect to recent related approaches in the area of normative multiagent sys- tems. For these other approaches, see the special issue on normative multiagent systems in Computational and Mathematical Organization Theory[68], these DROPS proceedings, the proceedings of the biannual workshops on deontic logic in computer science (¢EON) and of the COIN workshop series. 1The layout of this paper follows the Øve questions above, addressing each of them in a new section. [less ▲]