Dynamics in Delegation and Revocation Schemes: A Logical Approach

in DBSec (2011)

In this paper we first introduce a logic for describing formally a family of delegation and revocation models that are based on the work in Hagström et al.. We then extend our logic to accommodate an ... [more ▼]

In this paper we first introduce a logic for describing formally a family of delegation and revocation models that are based on the work in Hagström et al.. We then extend our logic to accommodate an epistemic interpretation of trust within the framework that we define. What emerges from this work is a rich framework of formally well-defined delegation and revocation schemes that accommodates an important trust component. [less ▲]

Rules, Agents and Norms: Guidelines for Rule-Based Normative Multi-Agent Systems

in RuleML Europe (2011)

In this survey paper we focus on some requirements for developing normative multi-agent systems (NMAS). In particular, we discuss Boella et al.’s guidelines proposed for NMAS. Finally, we deal with two ... [more ▼]

In this survey paper we focus on some requirements for developing normative multi-agent systems (NMAS). In particular, we discuss Boella et al.’s guidelines proposed for NMAS. Finally, we deal with two more specific questions concerning the role of norms in rule-based NMAS: the concepts of compliance and norm change. [less ▲]

Conviviality Measures

in Proceedings of 10th Int. Conf. on Autonomous Agents and Multiagent Systems (AAMAS 2011) (2011)

Conviviality has been introduced as a social science concept for multiagent systems to highlight soft qualitative requirements like user friendliness of systems. In this paper we introduce formal ... [more ▼]

Conviviality has been introduced as a social science concept for multiagent systems to highlight soft qualitative requirements like user friendliness of systems. In this paper we introduce formal conviviality measures for dependence networks using a coalitional game theoretic framework, which we contrast with more traditional efficiency and stability measures. Roughly, more opportunities to work with other people increases the conviviality, whereas larger coalitions may decrease the efficiency or stability of these involved coalitions. We first introduce assumptions and requirements, then we introduce a classification, and finally we introduce the conviviality measures. We use a running example from robotics to illustrate the measures. [less ▲]

Privacy Policies with Modal Logic: The Dynamic Turn

in DEON (2010)

Privacy policies are often defined in terms of permitted messages. Instead, in this paper we derive dynamically the permitted messages from static privacy policies defined in terms of permitted and ... [more ▼]

Privacy policies are often defined in terms of permitted messages. Instead, in this paper we derive dynamically the permitted messages from static privacy policies defined in terms of permitted and obligatory knowledge. With this new approach, we do not have to specify the permissions and prohibitions of all message combinations explicitly. To specify and reason about such privacy policies, we extend a multi-modal logic introduced by Cuppens and Demolombe with update operators modeling the dynamics of both knowledge and privacy policies. We show also how to determine the obligatory messages, how to express epistemic norms, and how to check whether a situation is compliant with respect to a privacy policy.We axiomatize and prove the decidability of our logic. [less ▲]

Arguing about Trust in Multiagent Systems

in Proceedings of the 11th Symposium on Artificial Intelligence of the Italian Association for Artificial Intelligence (AIIA'10) (2010)

Trust in multiagent systems is used for seeking to minimize the uncertainty in the interactions among the agents. In this paper, we discuss how to use argumentation to reason about trust. Using the ... [more ▼]

Trust in multiagent systems is used for seeking to minimize the uncertainty in the interactions among the agents. In this paper, we discuss how to use argumentation to reason about trust. Using the methodology of meta-argumentation, first we represent the source of the information from which the argument is constructed in the abstract argumentation framework capturing the fact that b is attacked because b is from a particular source s. We show how a source of information can be attacked if it is not evaluated as trustworthy. Second, we provide a fine grained representation of the trust relationships between the information sources in which trust concerns not only the sources but also the single arguments and attack relations the sources propose. Moreover, we represent the evidences in support of the arguments which are put forward by the information sources and the agents can express arguments by referring to other agents’ arguments. Meta-argumentation allows us not to extend Dung’s abstract argumentation framework by introducing trust and to reuse those principles and properties defined for Dung’s framework. [less ▲]

Convivial ambient technologies: Requirements, ontology, and design

in Computer Journal (2010), 53(8), 12291256

In this paper we discuss the use of the social concept ‘conviviality’ for computer science in general, and for the development of ambient technologies in particular. First, we give a survey of the use of ... [more ▼]

In this paper we discuss the use of the social concept ‘conviviality’ for computer science in general, and for the development of ambient technologies in particular. First, we give a survey of the use of the concept ‘conviviality’ in the social sciences. Conviviality is usually considered a positive concept related to sociability. However, further analysis reveals a negative side related to lack of diversity, privacy and ethical issues. Second, we argue that conviviality requirements for ambient intelligence are challenging, because ambient technologies give rise to a new virtual and social reality, and conviviality issues play a central role in applications that are concerned with the interaction of material, virtual and social realities. Conviviality highlights an important challenge that we illustrate with examples that emphasize ethical issues, such as privacy threats, surveillance of users and identity theft. Intelligent interfaces, for example, allow instant interactions and thereby create strong needs for coordination and regulation mechanisms that have to be addressed to ensure the safeguard of individuals against abuses, such as privacy intrusions and identity manipulations. Third, we propose a conviviality ontology by operationalizing the fuzzy concept of ‘conviviality,’ such that it can be used in computer science in the same way as other social concepts such as ‘service,’ ‘contract’ or ‘trust’ are used in this area. Conviviality is defined using dependence networks, and tools for conviviality are based on, what we call, conviviality masks. Fourth, we illustrate how convivial ambient intelligence applications can be designed using our operationalized concept of conviviality. We illustrate our arguments and contributions with a running example on the use of ambient technologies in digital cities, as a prototypical example where material reality such as ambient technologies interacts with virtual and social realities. [less ▲]

Group Intentions are Social Choice with Commitment

in Proceedings of the 11th International Workshop on Coordination, Optimization, Institution and Norms in Multiagent Systems (COIN@MALLOW'10) (2010)

An agent intends g if it has chosen to pursue goal g an is committed to pursuing g . How do groups decide on a common goal? Social epistemology offers two views on collective attitudes: according to the ... [more ▼]

An agent intends g if it has chosen to pursue goal g an is committed to pursuing g . How do groups decide on a common goal? Social epistemology offers two views on collective attitudes: according to the summative approach, a group has attitude p if all or most of the group members have the attitude p; according to the non-summative approach, for a group to have attitude p it is required that the members together agree that they have attitude p. The summative approach is used extensively in multi-agent systems. We propose a formalization of non-summative group intentions, using social choice to determine the group goals. We use judgment aggregation as a decision-making mechanism and a multi-modal multi-agent logic to represent the collective attitudes, as well as the commitment and revision strategies for the groups intentions. [less ▲]

Deontic Redundancy: A Fundamental Challenge for Deontic Logic

in DEON (2010)

To decide which norms can be removed from a system, we need to know when a norm is redundant. After shifting the focus of attention in deontic logic from detachment of obligations and permissions to ... [more ▼]

To decide which norms can be removed from a system, we need to know when a norm is redundant. After shifting the focus of attention in deontic logic from detachment of obligations and permissions to deontic redundancy, I discuss in this paper five benchmark examples of deontic redundancy in reasoning about permissions, intermediate concepts and constitutive norms, deontic dilemmas, temporal deontic reasoning and contrary-to-duty reasoning. Then I discuss those benchmark examples in four formal approaches to deontic reasoning: traditional model logic, dynamic approaches, violation oriented or diagnostic systems, and imperativist or norm based approaches. [less ▲]

Algorithms for finding coalitions exploiting a new reciprocity condition

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 ▲]

Norm Negotiation in Online Multi-Player Games

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 ▲]