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See detailHigher-Order Coalition Logic
Boella, Guido UL; Gabbay, Dov M. UL; Genovese, Valerio UL et al

in Bibliothèque(s) : revue de l'Association des bibliothécaires de France (2010)

We introduce and study higher-order coalition logic, a multi modal monadic second-order logic with operators [{x}ψ]φ expressing that the coalition of all agents satisfying ψ(x) can achieve a state in ... [more ▼]

We introduce and study higher-order coalition logic, a multi modal monadic second-order logic with operators [{x}ψ]φ expressing that the coalition of all agents satisfying ψ(x) can achieve a state in which φ holds. We use neighborhood semantics to model extensive games of perfect information with simultaneous actions and we provide a framework reasoning about agents in the same way as it is reasoning about their abilities. We illustrate higher-order coalition logic to represent and reason about coalition formation and cooperation, we show a more general and expressive way to quantify over coalitions than quantified coalition logic, we give an axiomatization and prove completeness. [less ▲]

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See detailFive guidelines for normative multiagent systems
Boella, Guido UL; Pigozzi, Gabriella UL; van der Torre, Leon UL

in Proceedings of JURIX 2009 - The 22nd International Conference on Legal Knowledge and Information Systems (2009, December)

n this paper we introduce and discuss five guidelines for the use of normative systems in computer science. We adopt a multiagent systems perspective, because norms are used to coordinate, organize, guide ... [more ▼]

n this paper we introduce and discuss five guidelines for the use of normative systems in computer science. We adopt a multiagent systems perspective, because norms are used to coordinate, organize, guide, regulate or control interaction among distributed autonomous systems. They are derived from the computer science literature. From the so-called ‘normchange’ definition of the first workshop on normative multiagent systems in 2005 we derive the guidelines to motivate which definition of normative multiagent system is used, to make explicit why norms are a kind of (soft) constraints deserving special analysis, and to explain why and how norms can be changed at runtime. From the so-called ‘mechanism design’ definition of the second workshop on normative multiagent systems in 2007 we derive the guidelines to discuss the use and role of norms as a mechanism in a game-theoretic setting, and to clarify the role of norms in the multiagent system. [less ▲]

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See detailAlgorithms for finding coalitions exploiting a new reciprocity condition
Boella, Guido UL; Sauro, Luigi UL; van der Torre, Leon UL

in Logic Journal of the IGPL (2009), 17(3), 273297

We introduce a reciprocity criterion for coalition formation among goal-directed agents, which we call the indecomposable do-ut-des property. It refines an older reciprocity property, called the do-ut-des ... [more ▼]

We introduce a reciprocity criterion for coalition formation among goal-directed agents, which we call the indecomposable do-ut-des property. It refines an older reciprocity property, called the do-ut-des or give-to-get property by considering the fact that agents prefer to form coalitions whose components cannot be formed independently. A formal description of this property is provided as well as an analysis of algorithms and their complexity. We provide an algorithm to decide whether a coalition has the desired property, and we show that the problem to verify whether a single coalition satisfies the property is tractable. Moreover, we provide an algorithm to search all the sub-coalitions of a given coalition satisfying the new property. Even if this problem is not computationally tractable, we show that in several cases, also the complexity of this problem may decrease considerably. [less ▲]

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See detailChecking Consistency in role oriented Dependence Networks
Boella, Guido UL; Genovese, Valerio UL; van der Torre, Leon UL et al

in BNAIC 2009: 21th Belgian - Netherlands Conference on Artificial Intelligence (2009)

In this paper we first formalize dependence networks that can be automaticaly build to model goalbased relationships among agents. Then, we propose three algorithms to build and check the consistency of a ... [more ▼]

In this paper we first formalize dependence networks that can be automaticaly build to model goalbased relationships among agents. Then, we propose three algorithms to build and check the consistency of a dependence network. We start presenting the elements composing our ontology such as agents, goals, skills, dependencies with the addition of the institutional notions of roles, institutional goals, institutional skills. We investigate the reasons behind the possible inconsistencies in building the combined dependence network and we propose an algorithm to check them [less ▲]

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See detailOn the Acceptability of Meta-Arguments
Boella, Guido UL; van der Torre, Leon UL; Villata, Serena

in Proceedings of IAT 2009: Procs. of IEEE/WIC/ACM International Conference on Intelligent Agent Technology (2009)

In this paper we introduce a theory of meta-argumentation, by using Dung’s theory of abstract argumentation to reason about itself. Meta-arguments are generated from atomic arguments, and extensions of ... [more ▼]

In this paper we introduce a theory of meta-argumentation, by using Dung’s theory of abstract argumentation to reason about itself. Meta-arguments are generated from atomic arguments, and extensions of acceptable meta-arguments are based on Dung’s argumentation semantics. To illustrate our theory, we show how to represent Toulmin schemes in this theory by introducing meta-arguments using the Caminada labeling, and meta-arguments for support [less ▲]

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See detailA Conviviality Measure for Early Requirement Phase of Multiagent System Design
Caire, Patrice UL; van der Torre, Leon UL

in Normative Multiagent Systems (2009)

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See detailTemporal Dependence Networks for the Design of Convivial Multiagent Systems
Caire, Patrice UL; van der Torre, Leon UL

in Proceedings of the Eighth International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS (2009)

We show how to use TROPOS as a design methodology for convivial multi-agent systems. We introduce temporal dependence networks to measure the evolution of conviviality over time, and we compare them to ... [more ▼]

We show how to use TROPOS as a design methodology for convivial multi-agent systems. We introduce temporal dependence networks to measure the evolution of conviviality over time, and we compare them to dynamic dependence networks introduced for conviviality masks and internal dynamics. [less ▲]

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See detailThe Design of Convivial Multiagent Systems
Caire, Patrice UL; van der Torre, Leon UL

in Social Networks and Multiagent Systems symposium; Artificial Intelligence and Simulation of Behaviour, AISB, April 6-9, 2009 at the Heriot-Watt University, Edinburgh (Scotland). (2009)

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See detailInput/output logics
Parent, Xavier UL; van der Torre, Leon UL

in Abstract book of 9th De Morgan Workshop on Deontic Logic (2009)

In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Exa mples ... [more ▼]

In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Exa mples arise in contexts of conditional obligations, goals, ideals, preferences , actions, and beliefs. Our purpose is to develop a theory of such input/output operations . Four are singled out: simple- minded, basic (making intelligent use of disjunctiv e inputs), simple-minded reusable (in which outputs may be recycled as inputs), and b asic reusable. They are defined semantically and characterised by derivation rules, as well as in terms of relabeling procedures and modal operators. Their behaviour is studied on both semantic and syntactic levels [less ▲]

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See detailFibred security language
Boella, Guido; Gabbay, Dov M.; Genovese, Valerio UL et al

in Studia Logica (2009)

We study access control policies based on the says operator by introducing a logical framework called Fibred Security Language (FSL) which is able to deal with features like joint responsibility between ... [more ▼]

We study access control policies based on the says operator by introducing a logical framework called Fibred Security Language (FSL) which is able to deal with features like joint responsibility between sets of principals and to identify them by means of first-order formulas. FSL is based on a multimodal logic methodology. We first discuss the main contributions from the expressiveness point of view, we give semantics for the language both for classical and intuitionistic fragment), we then prove that in order to express well-known properties like ‘speaks-for’ or ‘hand-off’, defined in terms of says, we do not need second-order logic (unlike previous approaches) but a decidable fragment of first-order logic suffices. We propose a model-driven study of the says axiomatization by constraining the Kripke models in order to respect desirable security properties, we study how existing access control logics can be translated into FSL and we give completeness for the logic. [less ▲]

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See detailNorm Negotiation in Online Multi-Player Games
Boella, Guido UL; Caire, Patrice UL; van der Torre, Leon UL

in Knowledge & Information Systems (2009), 18(2), 137156

In this paper, we introduce an agent communication protocol and speech acts for norm negotiation. The protocol creates individual or contractual obligations to fulfill goals of the agents based on the so ... [more ▼]

In this paper, we introduce an agent communication protocol and speech acts for norm negotiation. The protocol creates individual or contractual obligations to fulfill goals of the agents based on the so-called social delegation cycle. First, agents communicate their individual goals and powers. Second, they propose social goals which can be accepted or rejected by other agents. Third, they propose obligations and sanctions to achieve the social goal, which can again be accepted or rejected. Finally, the agents accept the new norm by indicating which of their communicated individual goals the norm achieves. The semantics of the speech acts is based on a commitment to public mental attitudes. The norm negotiation model is illustrated by an example of norm negotiation in multi-player online gaming. [less ▲]

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See detailAnalyzing Cooperation in Iterative Social Network Design
Boella, Guido UL; van der Torre, Leon UL; Villata, Serena

in Journal of Universal Computer Science (2009), 15(13),

We introduce an approach to iteratively design `small' social networks used in software engineering together with methods analyzing the cooperation in the system. The degree of cooperation is measured by ... [more ▼]

We introduce an approach to iteratively design `small' social networks used in software engineering together with methods analyzing the cooperation in the system. The degree of cooperation is measured by the emergence of coalitions and their stability over time. At the most abstract level, which we call the coalition view, coalitions are abstract entities that may dominate or attack other coalitions. During iterative design, these abstract entities are refined with agents and their dependencies constituting the coalitions (dependence view), the powers of sets of agents to see to goals (power view) and finally the beliefs, plans, tasks and goals of agents (agent view). The analysis methods predict the emergence of coalitions based on reciprocity and argumentation theory. [less ▲]

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See detailThe role of goals in belief selection
Boella, Guido UL; Pereira, Célia Da Costa UL; Pigozzi, Gabriella UL et al

in Logic Journal of the IGPL (2009)

In this paper we consider the relation between beliefs and goals in agent theory. Beliefs play three roles in reasoning about goals: they play a role in the generation of unconditional desires from ... [more ▼]

In this paper we consider the relation between beliefs and goals in agent theory. Beliefs play three roles in reasoning about goals: they play a role in the generation of unconditional desires from conditional ones, they play a role in adoption of desires as goals, and they play a role in the selection of plans to achieve goals. In this paper we consider the role of goals in reasoning about beliefs. Though we assume that goals do not play a role in the belief generation problem, we argue that they play a role in the belief selection problem. We show the rationality of the use of goals in belief selection, in the sense that there are cases in which agents that take their goals into account in selecting a belief set from a set of alternatives outperform agents that do not do so. We also formally distinguish between the rational role of goals in belief selection and irrational wishful thinking. [less ▲]

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See detailDynamics in Argumentation with Single Extensions: Abstraction Principles and the Grounded Extension
Boella, Guido UL; Kaci, Souhila UL; van der Torre, Leon UL

in Symbolic and Quantitative Approaches to Reasoning with Uncertainty, 10th European Conference, ECSQARU 2009, Verona, Italy, July 1-3, 2009. Proceedings (2009)

In this paper we consider the dynamics of abstract argumentation in Baroni and Giacomin’s framework for the evaluation of extension based argumentation semantics. Following Baroni and Giacomin, we do not ... [more ▼]

In this paper we consider the dynamics of abstract argumentation in Baroni and Giacomin’s framework for the evaluation of extension based argumentation semantics. Following Baroni and Giacomin, we do not consider individual approaches, but we define general principles or postulates that individual approaches may satisfy. In particular, we define abstraction principles for the attack relation, and for the arguments in the framework. We illustrate the principles on the grounded extension. In this paper we consider only principles for the single extension case, and leave the multiple extension case to further research. [less ▲]

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See detailA Middleware for modeling Organizations and Roles in Jade
Baldoni, Matteo UL; Boella, Guido UL; Genovese, Valerio UL et al

in Proceedings of PROMAS (2009)

Organizations and roles are often seen as mental constructs, good to be used during the design phase in Multi Agent Systems, but they have also been considered as first class citizens in MAS, when ... [more ▼]

Organizations and roles are often seen as mental constructs, good to be used during the design phase in Multi Agent Systems, but they have also been considered as first class citizens in MAS, when objective coordination is needed. Roles facilitate the coordination of agents inside an organization, and they give new abilities in the context of organizations, called powers, to the agents which satisfy the necessary requirements to play them. No general purpose programming languages for multiagent systems offer primitives to program organizations and roles as instances existing at runtime, so, in this paper, we propose our extension of the Jade framework, with Java primitives to program organizations structured in roles, and to enable agents to play roles in organizations. We provide classes and protocols which enable an agent to enact a new role in an organization, to interact with the role by invoking the execution of powers, and to receive new goals to be fulfilled. Roles and organizations can be on a different platform with respect to the role players, and communication is protocol-based. Since they can have complex behaviours, they are implemented by extending the Jade agent class. Our aim is to give to programmers a middle tier, built on the Jade platform, useful to solve with minimal implementative effort many coordination problems, and to offer a first, implicit, management of norms and sanctions. [less ▲]

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See detailA Normative Multiagent Approach to Requirements Engineering
Boella, Guido UL; Broersen, Jan UL; van der Torre, Leon UL et al

in Postproceedings COIN@AAMAS 2009 (2009)

In this paper we present a new model, called NorMAS-RE, for the requirements analysis of a system. NorMAS-RE is a new model based on the multiagent systems paradigm with the aim to support the ... [more ▼]

In this paper we present a new model, called NorMAS-RE, for the requirements analysis of a system. NorMAS-RE is a new model based on the multiagent systems paradigm with the aim to support the requirements analysis phase of systems design. This model offers a structured approach to requirements analysis, based on conceptual models defined following a visual modeling language, called dependence networks. The main elements of this visual language are the agents with their goals, capabilities and facts, similarly to the TROPOS methodology [10]. The normative component is present both in the ontology and in the conceptual metamodel, associating agents to roles they play inside the systems and a set of goals, capabilities and facts proper of these roles. This improvement allows to define different types of dependence networks, called dynamic dependence networks and conditional dependence networks, representing the different phases of the requirements analysis of the system. This paper presents a requirements analysis model based on normative concepts such as obligation and institution. The NorMAS-RE model is a model of semiformal specification featured by an ontology, a meta-model, a graphical notation and a set of constraints. Our model, moreover, allows the definition of the notion of coalition for the different kinds of network. We present our model using the scenario of virtual organizations based on a Grid network. [less ▲]

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See detailNormative framework for normative system change
Boella, Guido UL; Pigozzi, Gabriella UL; van der Torre, Leon UL

in Normative framework for normative system change (2009)

Normative systems in a multiagent system must be able to evolve over time, for example due to actions creating or removing norms in the system. The only formal framework to evaluate and classify normative ... [more ▼]

Normative systems in a multiagent system must be able to evolve over time, for example due to actions creating or removing norms in the system. The only formal framework to evaluate and classify normative system change methods is the so-called AGM framework of theory change, which has originally been developed as a framework to describe and classify both belief and normative system change. However, it has been used for belief change only, since the beliefs or norms are represented as propositional formulas. We therefore propose, as a normative framework for normative system change, to replace propositional formulas in the AGM framework of theory change by pairs of propositional formulas, representing the rule based character of norms, and to add several principles from the input/output logic framework. In this new framework, we show that some of the AGM properties cannot be expressed, and other properties are consistent only for some logics, but not for others. [less ▲]

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See detailFour Ways to Change Coalitions: Agents, Dependencies, Norms and Internal Dynamics
Boella, Guido UL; van der Torre, Leon UL; Villata, Serena

in Proceedings of COIN (2009)

We introduce a new formal approach to social networks in order to distinguish four ways in which coalitions change.First, the agents in the network change. Second, dependencies among the agents change ... [more ▼]

We introduce a new formal approach to social networks in order to distinguish four ways in which coalitions change.First, the agents in the network change. Second, dependencies among the agents change, for example due to addition or removal of powers and goals of the agents. Third, norms can introduce normative dependencies for obligations and prohibitions. Fourth, coalitions can change due to internal processes. We propose a number of stability measures to identify each one of the four proposed sources of coalitions ’dynamics and the consequences they induce on the stability of coalitions. [less ▲]

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See detailThe Interplay between Relationships, Roles and Objects
Boella, Guido UL; van der Torre, Leon UL

in Proceedings of FSEN09 (2009)

In this paper we study the interconnection between relationships and roles. We start from the patterns used to introduce relationships in object oriented languages, and we show how the role model proposed ... [more ▼]

In this paper we study the interconnection between relationships and roles. We start from the patterns used to introduce relationships in object oriented languages, and we show how the role model proposed in powerJava can be used to define roles. In particular, we focus on how to implement roles in an abstract way in objects representing relationships, and to specify the interconnections between the roles. Abstract roles cannot be instantiated. To participate in a relationship, objects have to extend the abstract roles of the relationship. Only when roles are implemented in the objects offering them, they can be instantiated, thus allowing another object to play those roles. [less ▲]

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See detailRepresenting Excuses in Social Dependence Networks
Boella, Guido UL; Broersen, Jan UL; van der Torre, Leon UL et al

in AI*IA (2009)

In this paper, we propose a representation of excuses in the context of multiagent systems. We distinguish five classes of excuses, taking as starting point both jurisprudential and philosophical studies ... [more ▼]

In this paper, we propose a representation of excuses in the context of multiagent systems. We distinguish five classes of excuses, taking as starting point both jurisprudential and philosophical studies about this topic, and we discuss their acceptance criteria. We highlight the following classes of excuses: epistemic excuses, power-based excuses, norm-based excuses, counts as-based excuses and social-based excuses and we represent them using social dependence networks. The acceptance criteria individuate those excuses which success in maintaining the trust of the other agents, e.g. in the context of social networks, excuses based on norms seem better than counts as-based ones in achieving this aim. [less ▲]

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