Showing papers presented at "European Workshop on Multi-Agent Systems in 2013"

Agent-based modeling of social conflict, civil violence and revolution: State-of-the-art-review and further prospects

Abstract: In this paper, we present a state-of-the-art review of Agent-based models (ABM) for simulation of social conflict phenomena, such as peaceful or violent street protests, civil violence and revolution. First, a simplified characterization of social conflict phenomena as emergent properties of a complex system is presented, together with a description of their macro and micro levels and the scales of the emergent properties. Then, existing ABM for simulation of crowd dynamics, civil violence and revolution are analyzed and compared, using a framework that considers their purpose/scope, environment representation, agent types and their architecture, the scales of the emergent properties, the qualitative and quantitative understanding of the phenomena provided by the results obtained from the models. We discuss the strengths and limitations of the existing models, as well as the promising lines of research for filling the gaps between the state-of-the-art models and real phenomena. This review is part of a work in progress on the assembling and dynamics of protests and civil violence, involving both simulation of the assembling process and the protest dynamics, as well as data collection in real protest events, and provides hints and guidelines for future developments.

A Formal Model of Social Relations for Articial Companions

Abstract: For virtual agents to be implied in a long-term interaction with users, they have to be able to establish and maintain long-term relationships with them. In order to give the capability to a virtual agent to reason on its social relation with a user, we propose a BDI formalization of social relations. Based on psychological theories, we characterize social relation over three dimensions, namely dominance, liking and familiarity. Liking (of the agent toward a user) is defined as a like-mindedness between the agent and a user in terms preferences. The degree of liking can be computed from the number of shared preferences and their related importance for the agent. The agent’s dominance is defined as its power on the other’s intentions achievement. The level of dominance depends also on the other’s power. Finally, the agent’s familiarity is defined by the value of intimacy with a user and relies on the quantity of knowledge about a user’s beliefs and intentions. Based on the formal representation of social relation, the virtual agent may reason about the different strategies to adopt to deal with its relation with another agent (virtual or real).

A Possible Approach for Implementing Self-Awareness in JASON.

Abstract: In Philosophy, the term awareness is often associated to theories of consciousness and self-referential behavior. In computer science, the awareness is a topic of increasing relevance in both Software Engineering and Artificial Intelligence, being closely related to autonomy and proactiveness. We can distinguish two orders of awareness: the first order is the awareness of the environment also known as context-awareness; conversely, self-awareness is a higher order awareness (knowledge about one’s own mental states). Nowadays, many agent oriented languages offer native instruments to implement context-awareness. However, self-awareness is not adequately supported and it requires further considerations. This paper focuses on implementation techniques, based on JASON, for creating software agents able to dynamically reason about their knowledge of the environment, as well as on their missions, capabilities and current execution state.

Logics for Non-Cooperative Games with Expectations

Abstract: We introduce the logics E(G) for reasoning about probabilistic expectation over classes G of games with discrete polynomial payoff functions represented by finite-valued Lukasiewicz formulas and provide completeness and complexity results. In addition, we introduce a new class of games where players’ expected payoff functions are encoded by E(G)-formulas. In these games each player’s aim is to randomise her strategic choices in order to affect the other players’ expectations over an outcome as well as their own. We offer a logical and computational characterisation of this new class of games.

TrustE: An Emotional Trust Model for Agents.

Abstract: Trust and reputation have been proposed in the Multiagent Systems area as a way to assist agents to select good partners in order to improve interactions between them. As well as trust, agent emotions have been studied with the aim of making the actions and reactions of the agents more like those of humans. In this paper, we present a trust model based on emotions. It is a hybrid mathematical and symbolical model designed to capture the complexity of reasoning. Quantitative and qualitative evaluations are combined through the incorporation of some emotional elements in the trust evaluation.

Charters for Self-Evolving Communities

Abstract: This work is supported by the PRAISE project (funded by the European Commission under the FP7 STREP grant number 318770), the CBIT project (funded by the Spanish Ministry of Science & Innovation under the grant number TIN2010-16306), and the Agreement Technologies project (funded by CONSOLIDER CSD 2007-0022, INGENIO 2010).

On Binary Max-Sum and Tractable HOPs

Abstract: The Max-Sum message-passing algorithm has been used to approximately solve several unconstrained optimization problems, specially in the distributed context. In general, the complexity of computing messages is exponential. However, if the problem is modeled using the so called Tractable HOPs (THOPs), binary MaxSum’s messages can be computed in polynomial time. In this paper we review existing THOPs, and present new ones, aiming at providing an updated view of efficient message computation.

Shame, when reasoning and emotions are linked.

Abstract: Some emotions, described as "basic" in the literature, are almost reflexes. Other emotions are triggered via pattern matching mechanisms operating on specific mental states (most often epistemic and motivational) to determine the (in)congruence of these states. Yet other emotions come from more or less complex cognitive mechanisms (and we thus call them complex emotions) such as counterfactual reasoning (e.g. guilt or regret), normative judgement (e.g. shame or pride), probabilistic evaluations of the world (e.g. surprise), etc.. In the following, we study and formalise the complex emotion of shame that is of particular importance in social behaviour, and illustrate it on some scenarios.

Towards a Framework that Allows Using a Cognitive Architecture to Personalize Recommendations in e-Commerce.

Abstract: In this paper we propose the use of a cognitive architecture as a mechanism to improve the level of personalization in a recommendation process. The main idea is to use the cognitive architecture as an advisor that lies between the user and a set of specialized recommenders. The cognitive architecture should know about the strengths and weaknesses of the recommenders, when they can be used and their degree of reliability given the amount of information available, among other things. With this information and the detailed knowledge about the user needs, it should be able to provide much more reliable and trustful recommendations by combining the strengths of each recommender given the specific context. The flexibility of a cognitive architecture in this place of the recommendation process will allow also to consider a much more sophisticated interaction with the user by allowing for example argumentation processes between the user and the system.

A Logic for Social Influence through Communication

Abstract: We propose a two dimensional \social network plausibility framework" to model doxastic influence through communication in a social network. To do so, we combine two approaches: on the one hand, a hybrid logic setting, to model the social network itself (who is related to whom), and on the other hand, dynamic epistemic logic, to model the distribution of beliefs among agents (who believes what) and belief changes induced by communication events (what is said to whom and how do the hearers revise their beliefs). Combining both, we show how to design some particular communication protocols in this new framework to represent some level of social doxastic influence, assuming that the communicating agents are sincere and trust each other.

Structural Transitivity of Trust in Academic Social Networks Using Agent-Based Simulation.

Abstract: Research interest in social networks area can be explained mainly because this type of network: (i) promotes the interpersonal relationship; (ii) has a natural tendency for knowledge emergence; (iii) generates large volumes of information. This interest is reinforced due to the fact that since the 90's Web Social Networks, e.g. Facebook or Orkut, have millions of users around the world. Our proposal in this paper is to analyze the physical structure of three computer networks topologies centralized, decentralized and distributed – in a real academic social network, the Lattes Curriculum. The main question is how the network structure could influence the flow of the trust transitivity between the members of the network. Firstly, we conducted a survey with researchers about their trust in Lattes Curriculum and later we developed an agent-based model and simulated it to analyze the resulting data.

A coalition-based approach for cooperative urban traffic regulation

Abstract: Cooperative systems allow the exchange of large amounts of information either vehicle to vehicle or vehicle to infrastructure. New traffic control systems can take advantage of this information, thereby making more efficient traffic regulation. This is the underlying idea of the urban traffic control strategy presented in this paper. It assumes that the real time paths of all vehicles on the network are known. Coalitions of vehicles sharing the same parts of routes are built. Each coalition is monitored by a Coordinator Agent who communicates with intersections in order to get the best traffic light configuration for his vehicles. A genetic algorithm is used to find the optimal set of traffic light configurations which satisfy the Coordinator Agents' requests. The optimal solution is obtained within the set of the proposed solutions by negotiation between the Coordinator Agents in order to reduce the total travelling time in the network.

Self-deception and the Logic of Belief.

Abstract: The point of departure for this presentation is the brief discussion of self-deception that appears in Hintikka’s book Knowledge and Belief – An Introduction to the Logic of the Two Notions, Cornell UP, 1962. Hintikka starts from a remark by Montaigne: “Some make the world believe that they believe what they do not believe; others, in greater number, make themselves believe it”, and gives a formal treatment of (the second part of) Montaigne’s remark that parallels Hintikka’s analysis of Moore’s puzzle about saying and disbelieving. Those analyses depend crucially on the 4. schema for the logic of belief (later dubbed the ‘positive introspection schema’): Bap → BaBap

Shame: when emotion and reasoning are linked

Abstract: Some emotions, described as "basic" in the literature, are almost reflexes. Other emotions are triggered via pattern matching mechanisms operating on specific mental states (most often epistemic and motivational) to determine the (in)congruence of these states. Yet other emotions come from more or less complex cognitive mechanisms (and we thus call them complex emotions) such as counterfactual reasoning (e.g. guilt or regret), normative judgement (e.g. shame or pride), probabilistic evaluations of the world (e.g. surprise), etc.. In the following, we study and formalise the complex emotion of shame that is of particular importance in social behaviour, and illustrate it on some scenarios.

A Test Driven Development of MAS.

Abstract: Testing is a key software lifecycle activity to assure software quality. Although it is of recognized importance, the work on agent testing has been scarce and has been usually tied to a MAS design methodology. This article presents a methodology agnostic testing procedure along with the description of a testing toolkit for MAS, with a practical application to a real, in production MAS. We also present some insights into our practical experience testing MAS.

Extending Fictitious Play with Pattern Recognition

Abstract: Fictitious play, an algorithm to predict the opponents next move based on the observed history of play, is one of the oldest simple yet very effective algorithms in game theory. Although using pattern recognition as a more sophisticated way to analyze the history of play seems a logical step, there is little research available on this subject. In this paper we will examine two different types of pattern recognition, and formulate several algorithms that incorporate these approaches. These algorithms and the basic fictitious play variants they extend are empirically tested in eight tournaments on some well known formal-form games. The results obtained will show that adding pattern recognition to fictitious play improves performance, and demonstrate the general possibilities of applying pattern recognition to agents in game theory.

A metric for hexagonal grid-world cooperative object recognition tasks for a swarm of agents

Abstract: In the future nano-robots could be used in in-vivo medical applications. By using lattice robots as a unit of measurement tumours could be assessed as malignant or benign by considering the shape of their boundaries through cooperative object recognition. With the objective of moving towards this end goal research has been carried out using simulations on hexagonal lattices that allow simple agents to cooperate to distinguish between two objects’ shapes. This paper determines a method which gives a value of difference between any two objects constructed on a hexagonal lattice. This difference value will provide a metric for future cooperative object recognition scenarios. The measure of the difference value was calculated considering varying degrees of knowledge about sections of the objects’ boundaries. The results were compared to a simulated task with agents that were homogeneous, anonymous, had a limited sensor range and no common coordinate system. It was found that the difference value metric provides a significant correlation to the time taken to complete a series of cooperative object recognition scenarios.