CNRS Complex and Logical Algorithm Laboratory

Creteil, France

CNRS Complex and Logical Algorithm Laboratory

Creteil, France
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Condurache R.,Free University of Colombia | Condurache R.,CNRS Complex and Logical Algorithm Laboratory | Filiot E.,Free University of Colombia | Gentilini R.,University of Perugia | Raskin J.-F.,Free University of Colombia
Leibniz International Proceedings in Informatics, LIPIcs | Year: 2016

We study the computational complexity of the cooperative and non-cooperative rational synthesis problems, as introduced by Kupferman, Vardi and co-authors. We provide tight results for most of the classical omega-regular objectives, and show how to solve those problems optimally. © Rodica Condurache, Emmanuel Filiot, Raffaella Gentilini, and Jean-Francois Raskin.


Cervelle J.,CNRS Complex and Logical Algorithm Laboratory | Formenti E.,University of Nice Sophia Antipolis | Guillon P.,University of Chile
Leibniz International Proceedings in Informatics, LIPIcs | Year: 2010

A cellular automaton (CA) is a parallel synchronous computing model, which consists in a juxtaposition of finite automata (cells) whose state evolves according to that of their neighbors. Its trace is the set of infinite words representing the sequence of states taken by some particular cell. In this paper we study the ultimate trace of CA and partial CA (a CA restricted to a particular subshift). The ultimate trace is the trace observed after a long time run of the CA. We give sufficient conditions for a set of infinite words to be the trace of some CA and prove the undecidability of all properties over traces that are stable by ultimate coincidence. © J. Cervelle, E. Formenti, and P. Guillon.


Hurst W.,Liverpool John Moores University | Shone N.,Liverpool John Moores University | Monnet Q.,CNRS Complex and Logical Algorithm Laboratory
Proceedings - 15th IEEE International Conference on Computer and Information Technology, CIT 2015, 14th IEEE International Conference on Ubiquitous Computing and Communications, IUCC 2015, 13th IEEE International Conference on Dependable, Autonomic and Secure Computing, DASC 2015 and 13th IEEE International Conference on Pervasive Intelligence and Computing, PICom 2015 | Year: 2015

Over the last decade, the level of critical infrastructure technology has been steadily transforming in order to keep pace with the growing demand for the services offered. The implementation of the smart grid, which relies on a complex and intelligent level of interconnectivity, is one example of how vital amenity provision is being refined. However, with this change, the risk of threats from the digital domain must be calculated. Superior interconnectivity between infrastructures means that the future cascading impacts of successful cyberattacks are unknown. One such threat being faced in the digital domain is the Distributed Denial of Service (DDoS) attack. A DDoS has the goal of incapacitating a server, network or service, by barraging a target with external data traffic in the form of communication requests. DDoS have the potential to cause a critical infrastructure outage, and the subsequent impact on a network of such infrastructures is yet unknown. In this paper, an approach for assessing the future impacts of a cyber-attack in a network of critical infrastructures is presented; with a focus on DDoS attacks. A simulation of a critical infrastructure network provides data to represent both normal run-time and an attack scenario. Using this dataset, a technique for assessing the future impact of disruptions on integrated critical infrastructure network, is demonstrated. © 2015 Crown.


Cegielski P.,CNRS Complex and Logical Algorithm Laboratory | Grigorieff S.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Guessarian I.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Various problems on integers lead to the class of functions defined on a ring of numbers (or a subset of such a ring) and verifying a−b divides f(a)−f(b) for all a, b.We say that such functions are “congruence preserving”. In previous works, we characterized these classes of functions for the cases ℕ → ℤ, ℤ → ℤ and ℤ/nℤ → ℤ/mℤ in terms of sums series of rational polynomials (taking only integral values) and the function giving the least common multiple of 1, 2,..., k. In this paper we relate the finite and infinite cases via a notion of “lifting”: if π: X → Y is a surjective morphism and f is a function Y → Y a lifting of f is a function F: X → X such that π ◦ F = f ◦ π. We prove that the finite case ℤ/nℤ → ℤ/nℤ can be so lifted to the infinite cases ℕ → ℕ and ℤ → ℤ. We also use such liftings to extend the characterization to the rings of p-adic and profinite integers, using Mahler representation of continuous functions on these rings. © Springer International Publishing Switzerland 2015.


Aubert C.,CNRS Complex and Logical Algorithm Laboratory | Cristescu I.,University Paris Diderot
Electronic Proceedings in Theoretical Computer Science, EPTCS | Year: 2015

A standard contextual equivalence for process algebras is strong barbed congruence. Configuration structures are a denotational semantics for processes in which one can define equivalences that are more discriminating, i.e. that distinguish the denotation of terms equated by barbed congruence. Hereditary history preserving bisimulation (HHPB) is such a relation. We define a strong back and forth barbed congruence using a reversible process algebra and show that the relation induced by the back and forth congruence is equivalent to HHPB, providing a contextual characterization of HHPB. © C. Aubert & I. Cristescu.


Bozianu R.,CNRS Complex and Logical Algorithm Laboratory | Dima C.,CNRS Complex and Logical Algorithm Laboratory | Filiot E.,Free University of Colombia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

In this paper we address the synthesis problem for specifications given in linear temporal single-agent epistemic logic, KLTL (or KL 1), over single-agent systems having imperfect information of the environment state. [17] have shown that this problem is 2Exptime complete. However, their procedure relies on complex automata constructions that are notoriously resistant to efficient implementations as they use Safra-like determinization. We propose a "Safraless" synthesis procedure for a large fragment of KLTL. The construction transforms first the synthesis problem into the problem of checking emptiness for universal co-Büchi tree automata using an information-set construction. Then we build a safety game that can be solved using an antichain-based symbolic technique exploiting the structure of the underlying automata. The technique is implemented and applied to a couple of case studies. © 2014 Springer International Publishing.


Cegielski P.,CNRS Complex and Logical Algorithm Laboratory | Grigorieff S.,University Paris Diderot | Guessarian I.,University Paris Diderot
Information Processing Letters | Year: 2014

We consider lattices of regular sets of non negative integers, i.e. of sets definable in Presburger arithmetic. We prove that if such a lattice is closed under decrement then it is also closed under many other functions: quotients by an integer, roots, etc. We characterize the family of such functions. © 2013 Elsevier B.V.


Allombert V.,CNRS Complex and Logical Algorithm Laboratory | Gava F.,CNRS Complex and Logical Algorithm Laboratory | Tesson J.,CNRS Complex and Logical Algorithm Laboratory
International Journal of Parallel Programming | Year: 2016

bsp is a bridging model between abstract execution and concrete parallel systems. Structure and abstraction brought by bsp allow to have portable parallel programs with scalable performance predictions, without dealing with low-level details of architectures. In the past, we designed bsml for programming bsp algorithms in ml. However, the simplicity of the bsp model does not fit the complexity of today’s hierarchical architectures such as clusters of machines with multiple multi-core processors. The multi-bsp model is an extension of the bsp model which brings a tree-based view of nested components of hierarchical architectures. To program multi-bsp algorithms in ml, we propose the multi-ml language as an extension of bsml where a specific kind of recursion is used to go through a hierarchy of computing nodes. We define a formal semantics of the language and present preliminary experiments which show performance improvements with respect to bsml. © 2016 Springer Science+Business Media New York


Bes A.,CNRS Complex and Logical Algorithm Laboratory
Logical Methods in Computer Science | Year: 2013

We study expansions of the Weak Monadic Second Order theory of (N,<) by cardinality relations, which are predicates R(X1,...,Xn) whose truth value depends only on the cardinality of the sets X1,...,Xn. We first provide a (definable) criterion for definability of a cardinality relation in (N,<), and use it to prove that for every cardinality relation R which is not definable in (N,<), there exists a unary cardinality relation that is definable in (N,<,R) and not in (N,<). These results resemble Muchnik and Michaux-Villemaire theorems for Presburger Arithmetic. We prove then that + and × are definable in (N,<,R) for every cardinality relation R which is not definable in (N,<). This implies undecidability of the WMSO theory of (N,<,R). We also consider the related satisfiability problem for the class of finite orderings, namely the question whether an MSO sentence in the language {<,R} admits a finite model M where < is interpreted as a linear ordering, and R as the restriction of some (fixed) cardinality relation to the domain of M. We prove that this problem is undecidable for every cardinality relation R which is not definable in (N,<). © Alexis Bès.


Dima C.,CNRS Complex and Logical Algorithm Laboratory
Fundamenta Informaticae | Year: 2014

We give a discretization of behaviors of timed automata, in which timed languages are represented as sets of words containing action symbols, a clock tick symbol 1, and two delay symbols δ- (negative delay) and δ+ (positive delay). Unlike the region construction, our discretization commutes with intersection. We show that discretizations of timed automata are, in general, context-sensitive languages over S ∪ {1, δ+, δ-}, and give a class of counter automata that accepts exactly the class of languages that are discretizations of timed automata, and show that its emptiness problem is decidable.

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