Analyzing Conflict Freedom For Multi-threaded Programs With Time Annotations

Avoiding access conflicts is a major challenge in the design of multi-threaded programs. In the context of real-time systems, the absence of conflicts can be guaranteed by ensuring that no two potentially conflicting accesses are ever scheduled concurrently.In this paper, we analyze programs that carry time annotations specifying the time for executing each statement. We propose a technique for verifying that a multi-threaded program with time annotations is free of access conflicts. In particular, we generate constraints that reflect the possible schedules for executing the program and the required properties. We then invoke an SMT solver in order to verify that no execution gives rise to concurrent conflicting accesses. Otherwise, we obtain a trace that exhibits the access conflict.Comment: http://journal.ub.tu-berlin.de/eceasst/article/view/97

Nîmes – Îlot Grill

Date de l'opération : 1992 (SD) ; 1993 (SU) Inventeur(s) : Hervé Marie-Laure (AFAN) ; Duflot Laurence Plan général des opérations intra muros de Nîmes (Fig. n°3 : En noir, les principales fouilles réalisées entre 1965 et 1990 à l’intérieur de la ville du Haut-Empire, associées à quelques grands repères topographiques). À l’angle formé par le boulevard des Arènes, la rue de la République et la rue Alexandre-Ducros (EZ-474, 475), un projet immobilier devait concerner des parcelles situées sur ..

Nîmes – Îlot Grill

Date de l'opération : 1992 (SD) ; 1993 (SU) Inventeur(s) : Hervé Marie-Laure (AFAN) ; Duflot Laurence Plan général des opérations intra muros de Nîmes (Fig. n°3 : En noir, les principales fouilles réalisées entre 1965 et 1990 à l’intérieur de la ville du Haut-Empire, associées à quelques grands repères topographiques). À l’angle formé par le boulevard des Arènes, la rue de la République et la rue Alexandre-Ducros (EZ-474, 475), un projet immobilier devait concerner des parcelles situées sur ..

Bounding messages for free in security protocols - extension to various security properties

International audienceWhile the verification of security protocols has been proved to be undecidable in general, several approaches use simplifying hypotheses in order to obtain decidability for interesting subclasses. Amongst the most common is type abstraction, i.e. considering only well-typed runs of the protocol, therefore bounding message length. In this paper, we show how to get message boundedness “for free” under a reasonable (syntactic) assumption on protocols, in order to verify a variety of interesting security properties including secrecy and several authentication properties. This enables us to improve existing decidability results by restricting the search space for attacks

Statistical Model Checking of Distributed Programs within SimGrid

International audienceIn this paper, we present an approach to perform statistical model-checking over stochastic distributed programs using the SimGrid framework. The distributed programs are modeled using SimGrid, a fast and lightweight framework for the simulation of distributed programs, which we have enhanced in three ways: a cleaner description of the probabilistic evolution of the capacities of resources, a centralized random number generator, and a protocol for the observation of the simulations. We also propose a toolset for the statistical model-checking of those simulated distributed programs, and in particular a prototype tool SimGridStatMC. The toolset is illustrated to evaluate various properties of an implementation of the peer to peer BitTorrent protocol

Probabilistic Model Checking of the CSMA/CD Protocol Using PRISM and APMC

AbstractCarrier Sense Multiple Access/Collision Detection (CSMA/CD) is the protocol for carrier transmission access in Ethernet networks (international standard IEEE 802.3). On Ethernet, any Network Interface Card (NIC) can try to send a packet in a channel at any time. If another NIC tries to send a packet at the same time, a collision is said to occur and the packets are discarded. The CSMA/CD protocol was designed to avoid this problem, more precisely to allow a NIC to send its packet without collision. This is done by way of a randomized exponential backoff process. In this paper, we analyse the correctness of the CSMA/CD protocol, using techniques from probabilistic model checking and approximate probabilistic model checking. The tools that we use are PRISM and APMC. Moreover, we provide a quantitative analysis of some CSMA/CD properties

Satisfiability techniques for computing minimal tie sets in reliability assessment

Estimates of system reliability crucially rely on qualitative techniques for determining the impact of component failures. Formally, the structure function of a system determines minimal tie or cut sets that are instrumental for quantitative techniques of reliability assessment. This paper describes three techniques, based on Boolean satisfiability solving, for computing minimal tie sets

Integrating satisfiability solving in the assessment of system reliability modeled by dynamic fault trees

International audienceFault trees (FTs) and their extensions are diagrammatic formalisms that are commonly used for reliability assessment and that represent the structure function of systems. The structure function determines tie sets and cut sets, and minimal tie sets are instrumental for assessing systems reliability. In a previous paper, we used satisfiability (SAT) techniques to compute tie sets from the structure function. In this paper we define minimal tie sets with sequences (MTSSs) as an extension of minimal tie sets for analyzing dynamic fault trees (DFTs), and we extend our previous techniques for computing MTSSs. We illustrate our approach using a standard case study and assess its performance over several industrial-size benchmarks

Evaluation de la robustesse d'un ordonnancement par Automates Temporisés Stochastiques

National audienceLes modèles et outils des SystèmesSystèmes`Systèmesà Evénéments Discrets (SED) ont montré leur apport et leur efficacité pour la modélisation et la résolution deprobì emes d'ordonnancement dans le domaine des systèmes manufacturiers de production. Leur principal atout réside dans leur capacitécapacité`capacitéà appréhender naturellement les dynamiques sous-jacentes aux ressources de production ainsi que les logiques de configuration des ateliers (Job-shop, Flow-shop, Open-shop, hybrides...). De plus, les extensions stochastiques des modèles de SED offrent d'intéressantes perspectives pour la prise en compte de l'incertain en ordonnancement : incertitudes sur les ressources (durée opératoires, aléas de fonctionnement, pannes...) mais aussi sur la de-mande (variabilité importante des produits, personnalisation de masse...). L'objectif de cet article est de démontrer la faisabilité d'une approche basée sur les automates tem-porisés stochastiques et sur des techniques de model-checking statistique pourévaluerpourévaluer la robustesse d'un ordonnancement facè a des aléas en se restreignant, dans le cadre de cettécetté etude, aux incertitudes sur les durées opératoires

Vital signs prediction and early warning score calculation based on continuous monitoring of hospitalised patients using wearable technology

In this prospective, interventional, international study, we investigate continuous monitoring of hospitalised patients’ vital signs using wearable technology as a basis for real-time early warning scores (EWS) estimation and vital signs time-series prediction. The collected continuous monitored vital signs are heart rate, blood pressure, respiration rate, and oxygen saturation of a heterogeneous patient population hospitalised in cardiology, postsurgical, and dialysis wards. Two aspects are elaborated in this study. The first is the high-rate (every minute) estimation of the statistical values (e.g., minimum and mean) of the vital signs components of the EWS for one-minute segments in contrast with the conventional routine of 2 to 3 times per day. The second aspect explores the use of a hybrid machine learning algorithm of kNN-LS-SVM for predicting future values of monitored vital signs. It is demonstrated that a real-time implementation of EWS in clinical practice is possible. Furthermore, we showed a promising prediction performance of vital signs compared to the most recent state of the art of a boosted approach of LSTM. The reported mean absolute percentage errors of predicting one-hour averaged heart rate are 4.1, 4.5, and 5% for the upcoming one, two, and three hours respectively for cardiology patients. The obtained results in this study show the potential of using wearable technology to continuously monitor the vital signs of hospitalised patients as the real-time estimation of EWS in addition to a reliable prediction of the future values of these vital signs is presented. Ultimately, both approaches of high-rate EWS computation and vital signs time-series prediction is promising to provide efficient cost-utility, ease of mobility and portability, streaming analytics, and early warning for vital signs deterioration