Catálogo de publicaciones - libros

We consider the problem of verifying game equilibria in multi-agent systems. We first identify a certain class of games where Nash or Bayesian Nash equilibria can be verified in polynomial time. Second, we show that verifying a dominant strategy equilibrium is NP-complete even for normal form games. Eventually, we consider general games and discuss the complexity of equilibrium verification.

In this paper, we present a scheme for the design of mobile agents applications based on components. There is still a paramount issue to overcome in mobile agent technology to allow its popularization: the high programming complexity. The proposed scheme enables secure mobile agent creation by the composition of code components, significantly simplifying the work for the developer. Agent features like itinerary protection, results retrieving, or fault-tolerance can be achieved through reusable components. Our proposal is a steady step forward for the promotion of mobile agent applications.

Natural systems are regarded as rich sources of inspiration for engineering artificial systems, particularly when adopting the multiagent system (MAS) paradigm. To promote a systematic reuse of mechanisms featured in self-organising systems, we analyse a selection of design patterns devised from the self-organisation literature. Starting from our reference MAS metamodel, we propose a pattern scheme that reflects the peculiarities of self-organising systems. Then, we provide a complete characterisation of each pattern, with particular attention to the problem description, the solution with respect to our metamodel, the natural systems which have inspired the pattern and known applications.

In this paper, we present an approach for adaptive replication to support fault tolerance. This approach uses a feedback control theory methodology within an adaptive replication infrastructure to determine replication degrees of replica groups. We implemented this approach in a multi-agent system to survive Byzantine failures. At the end of the paper, we also provide some experimental results to show the effectiveness of our approach.

In small scale multi-agent environments, every agent is aware of all of the others. This allows agents to evaluate the potential outcomes of their interaction for each of their possible interaction partners. However, this farsighted knowledge becomes an issue in large scale systems, leading to a combinatorial explosion in evaluation and is unrealistic in communication terms. Limited awareness of other agents is therefore the only plausible scenario in many large-scale environments. This limited awareness can be modeled as a sparse social network in which agents only interact with a limited subset of agents known to them. In this paper, we explore a model of dynamic multi-agent coalition formation in which agents are connected via fixed underlying social networks that exhibit different well known structures such as , and topologies. Agents follow different exploratory policies and are distributed in the network according to a variety of metrics. The primary results of the paper are to demonstrate different positive and negative properties of each topology for the coalition formation problem. In particular we show that despite positive properties for many problems, topologies introduce blocking factors which hinder the emergence of good coalition solutions in many configurations.

In this paper we focus on a new approach for the definition of context-based compatibility and substitutability of roles in MAS, and provide a formal framework for modeling roles together with their composition. First, we introduce the concept of usability of roles, and based on that we define two flexible roles compatibility relations depending on the context (environment). The proposed compatibility relations take into account the property preservation such as the completion and the proper termination of roles. Then, our formal framework is enhanced with the definition of two flexible behavioral subtyping relations related to the principle of substitutability. Finally, we show the existing link between compatibility and substitutability of roles, namely the preservation of the proposed compatibility relations by substitutability.

Multiagent systems may be elegantly modeled and designed by enhancing the role of the environment in which agents evolve. In particular, the environment may have the role of a governing infrastructure that regulates with laws or norms the actions taken by the agents. The focus of modeling and design is thus shifted from a subjective view of agents towards a more objective view of the whole multiagent system. In this paper, we apply the idea of a governing environment to model and design a multi-agent system that micro-simulates the Swiss highway network. The goal of the simulation is to show how traffic jams and accordion phenomena may be handled with appropriate local regulations on speed limits. A natural modeling would give segments the capacity to regulate the speed based on observed local events. We developed the simulation platform from scratch in order to accommodate our design choices and a realistic complexity. This paper presents in details our modeling choices, and first experimental results.

Multi-Agent Systems (MAS) in health-care domains are showing a rapid increase, in order to manage complex tasks and adapt gracefully to unexpected events. On the other hand, the lack of well-established agent-oriented engineering methodologies to transform knowledge level descriptions into deployable agent systems slackens MAS development. This paper presents a new methodology in modelling and automatically implementing agents in a home care domain. The representation of the application knowledge together with the codification of health care treatments lead to flexible realization of an agent platform that has the capability to capture new medical knowledge emerging from physicians.

In this paper we present a logic to provide a framework for the formal specification of multiagent real-time systems which allows explicit reasoning about the actions of agents, the nondeterministic model of interaction between agents and environment, the cooperation and competition of agents and the reaction time limits of a system. The logic combines Propositional Dynamic Logic and Alternating-time Temporal Logic and extends the formalism with reaction time constraints. We introduce a multiagent system abstract model and show how the logic can be used to specify the model properties.

At present the agent paradigm is often used for computational modeling of human behavior in an organizational setting. However, not many of the existing computational approaches make use of a rich theoretical basis developed in social science. Therefore, often mathematically sound models are invalid in practice. This paper proposes a formal approach for modeling of characteristics and behavior of agents in organizations, diverse aspects of which are represented using an expressive formal framework. The approach is based on the theoretical findings from social science and enables analysis of how different organizational and environmental factors influence the behavior and performance of agents. The approach is illustrated by a simulation case study.