Vérification formelle des systèmes multi-agents auto-adaptatifs

A major challenge for the development of self-organizing MAS is to guarantee the convergence of the system to the overall function expected by an external observer and to ensure that agents are able to adapt to changes. In the literature, several works were based on simulation and model-checking to study self-organizing MAS. The simulation allows designers to experiment various settings and create some heuristics to facilitate the system design. Model checking provides support to discover deadlocks and properties violations. However, to cope with the complexity of self-organizing MAS, the designer also needs techniques that support not only verification, but also the development process itself. Moreover, such techniques should support disciplined development and facilitate reasoning about various aspects of the system behavior at different levels of abstraction. In this thesis, three essential contributions were made in the field of formal development and verification of self-organizing MAS: a formalization with the Event-B language of self-organizing MAS key concepts into three levels of abstraction, an experimentation of a top-down refinement strategy for the development of self-organizing MAS and the definition of a bottom-up refinement process based on refinement patterns.Un des défis majeurs pour le développement des Systèmes Multi-Agents (SMA) auto-organisateurs est de garantir la convergence du système vers la fonction globale attendue par un observateur externe et de garantir que les agents sont capables de s'adapter face aux perturbations. Dans la littérature, plusieurs travaux se sont basés sur la simulation et le model-checking pour analyser les SMA auto-organisateurs. La simulation permet aux concepteurs d'expérimenter plusieurs paramètres et de créer certaines heuristiques pour faciliter la conception du système. Le model-checking fournit un support pour découvrir les blocages et les violations de propriétés. Cependant, pour faire face à la complexité de la conception des SMA auto-organisateurs, le concepteur a également besoin de techniques qui prennent en charge non seulement la vérification, mais aussi le processus de développement lui-même. En outre, ces techniques doivent permettre un développement méthodique et faciliter le raisonnement sur divers aspects du comportement du système à différents niveaux d'abstraction. Dans cette thèse, trois contributions essentielles ont été apportées dans le cadre du développement et la vérification formelle des SMA auto-organisateurs: une formalisation à l'aide du langage B-événementiel des concepts clés de ces systèmes en trois niveaux d'abstraction (micro, méso et macro), une expérimentation d'une stratégie de raffinement descendante pour le développement des SMA auto-organisateurs et la proposition d'un processus de raffinement ascendant basé sur des patrons de raffinement

A Pattern based Modelling for Self-Organizing Multi-Agent Systems with Event-B

International audienceSelf-Organizing Multi-Agent Systems (SO-MAS) are defined as a set of autonomous entities called agents interacting together in order to achieve a given task. Generally, the development process of these systems is based on the bottom-up approach which focuses on the design of the entities individual behavior. The main question arising when developing SO-MAS is how to insure that the designed entities, when interacting together, will give rise to the desired behavior? Our proposition to deal with this question is to use formal methods. We propose a correct by construction method for systematic design of SO-MAS based on the use of design patterns and formal stepwise refinements. Our work gives guidelines to assist the designer when developing the individual behavior of the entities and prove its correctness at the early stages of the design process. The method is illustrated with the foraging ants’ case study

Formal Modelling and Verification of Cooperative Ant Behaviour in Event-B

International audienceMulti-agent technology is a promising approach to development of complex decentralised systems that dynamically adapt to changing environmental conditions. The main challenge while designing such multi-agent systems is to ensure that reachability of the system-level goals emerges through collaboration of autonomous agents despite changing operating conditions. In this paper, we present a case study in formal modelling and verification of a colony of foraging ants. We formalise the behaviour of cooperative ants in Event-B and verify by proofs that the desired system-level properties become achievable via agent collaboration. The applied refinement-based approach weaves proof-based verification into the formal development. It allows us to rigorously define constraints on the environment and the ant behaviour at different abstraction levels and systematically explore the relationships between system-level goals, environment and autonomous ants. We believe that the proposed approach helps to structure complex system requirements, facilitates formal analysis of various system interdependencies, and supports formalisation of intricate mechanisms of agent collaboration

A Stepwise Refinement based Development of Self-Organizing Multi-Agent Systems: Application to the Foraging Ants

International audienceThis paper proposes a formal modeling for Self-Organizing Multi-Agent Systems (SOMAS) based on stepwise refinements, with the Event-B language and the Temporal Logic of Actions (TLA). This modeling allows to develop this kind of systems in a more structured manner. In addition, it enables to reason, in a rigorous way, about the correctness of the derived models both at the individual level and the global level. Our work is illustrated by the foraging ants case study

Vers une modélisation formelle basée sur le raffinement des systèmes multi-agents auto-organisateurs

International audienceThe development of self-organizing MAS still lacks rigorous verification methods to ensure the convergence and resilience of the designed system. Such insurances can be obtained through the application of formal methods. However, the integration of these techniques is still modest due to the complexity of the dynamics of self-organizing MAS which makes the overall function emerging. In this article, we explore the potential of formal languages, in particular Event-B and the TLA logic to prove the convergence and the resilience of the system. We as- sume that these properties can first, be observed at the global level by simulation. Then, Formal techniques allow us to prove them. Our work is illustrated by the foraging ant’s case study.Le développement de SMA auto-organisateurs manque encore de méthodes rigoureuses de véri¿cation garantissant la robustesse et la résilience du système conçu. De telles assurances peuvent être obtenues grâce à l'application de méthodes formelles. Mais l'intégration de ces techniques de véri¿cation reste encore modeste due à la complexité liée à la dynamique des SMA auto-organisateurs qui fait émerger leur fonction globale. Dans cet article, nous explorons le potentiel des langages formels, en particulier B-événementiel et la logique TLA, pour prouver des propriétés liées à la convergence et la résilience. Nous supposons que ces propriétés pourront d'abord être observées au niveau global par simulation. Les techniques formelles nous permettront ensuite d'en faire la preuve. Notre travail est illustré par l'étude de cas des fourmis fourrageuses

A Stepwise Renement based Development of Self-Organizing Multi-Agent Systems: Application on the Foraging Ants (EUMAS 2013)

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