On the Decidability of a Fragment of preferential LTL

Linear Temporal Logic (LTL) has found extensive applications in Computer Science and Artificial Intelligence, notably as a formal framework for representing and verifying computer systems that vary over time. Non-monotonic reasoning, on the other hand, allows us to formalize and reason with exceptions and the dynamics of information. The goal of this paper is therefore to enrich temporal formalisms with non-monotonic reasoning features. We do so by investigating a preferential semantics for defeasible LTL along the lines of that extensively studied by Kraus et al. in the propositional case and recently extended to modal and description logics. The main contribution of the paper is a decidability result for a meaningful fragment of preferential LTL that can serve as the basis for further exploration of defeasibility in temporal formalisms

A One-Pass Tree-Shaped Tableau for Defeasible LTL

Defeasible Linear Temporal Logic is a defeasible temporal formalism for representing and verifying exception-tolerant systems. It is based on Linear Temporal Logic (LTL) and builds on the preferential approach of Kraus et al. for non-monotonic reasoning, which allows us to formalize and reason with exceptions. In this paper, we tackle the satisfiability checking problem for defeasible LTL. One of the methods for satisfiability checking in LTL is the one-pass tree shaped analytic tableau proposed by Reynolds. We adapt his tableau to defeasible LTL by integrating the preferential semantics to the method. The novelty of this work is in showing how the preferential semantics works in a tableau method for defeasible linear temporal logic. We introduce a sound and complete tableau method for a fragment that can serve as the basis for further exploring tableau methods for this logic

Web Services Composition Problem: Model and Complexity

International audienceIn the approach taken in this chapter, the composition problem is as follows: given a client service, a goal service and a set of available services, determine if there exists a mediator service that enables the communication between the client and the existing services in order to satisfy the client request, represented by the goal service. In this chapter’s model, available services that have access control constraints are considered. To formally capture these constraints, the chapter defines Web Services as Conditional Communicating Automata (CCA) in which communication is done through bounded ports. This chapter gives a detailed presentation of said model and gives complexity results of the composition problem

A propos du problème de la composition des services électroniques

International audienc

Une approche uniforme de la modélisation des systèmes de protection temporisés

International audienc

Security analysis in access control based on roles and views

International audienc

Safety problems in access control with temporal constraints

International audienceMost of access control mechanisms use the matrix model to represent protection states of computer systems. We present a variant of the access control matrix model obtained by incorporating temporal constraints saying that “subject s has right r on object o since at least duration d”. In connection with this enriched model, we also discuss the decidable and undecidable cases of one of the major themes of computer security, namely the classical safety problem for access control matrices

Résultats de complexité pour le problème de la composition d'agents

International audienceIn order to realize complex tasks by agents, it is sometimes necessary to compose them. The agent compositionhas been characterized either as a plan synthesis problem or as a software synthesis problem : given a goal and aset of agents, generate a composition of the agents that satisfies the goal. We propose algorithms, based on recentadvances in automated synthesis of controllers, for performing automated composition of agents. We also givecomplexity result concerning this problem.Pour que des agents puissent réaliser des tâches complexes, il est nécessaire de composer entre eux ces agents.La composition d’agents a été caractérisée comme étant un problème de synthèse de plan ou comme étant un problème de synthèse de logiciel : étant donnés un but et un ensemble d’agents, générer une composition des agents qui satisfait le but. Nous proposons des algorithmes, basés sur des résultats récents de synthèse automatique de contrôleurs, pour réaliser la composition automatique d’agents. Nous donnons également des résultats concernant la complexité de ce problème

Considérations relatives à la décidabilité et à la complexité du problème de la composition de services

International audienc

Automata synthesis by asynchronous orchestration with applications to web services composition

co-located with ICALP'08: 35th International Colloquium on Automata, Languages and ProgrammingInternational audienc