Efficient Diagnostic Generation for Boolean Equation Systems

Boolean Equation Systems (BESs) provide a useful framework for the verification of concurrent finite-state systems. In practice, it is desirable that a BES resolution also yields diagnostic information explaining, preferably in a concise way, the truth value computed for a given variable of the BES. Using a representation of BESs as extended boolean graphs (EBGs), we propose a characterization of full diagnostics (i.e., both examples and counterexamples) as a particular class of subgraphs of the EBG associated to a BES. We provide algorithms that compute examples and counterexamples in linear time and can be straightforwardly used to extend known (global or local) BES resolution algorithms with diagnostic generation facilities

Transparent First-class Futures and Distributed Components

International audienceFutures are special kind of values that allow the synchronisation of different processes. Futures are in fact identifiers for promised results of function calls that are still awaited. When the result is necessary for the computation, the process is blocked until the result is returned. We are interested in this paper in transparent first-class futures, and their use within distributed components. We say that futures are transparent if the result is automatically and implicitly awaited upon the first access to the value; and that futures are first-class if they can be transmitted between components as usual objects. Thus, because of the difficulty to identify future objects, analysing the behaviour of omponents using first-class transparent futures is challenging. This paper contributes with first a static representation for futures, second a means to detect local deadlocks in a component system with first class futures, and finally extensions to interface definitions in order to avoid such deadlocks

Transparent First-class Futures and Distributed Components

International audienceFutures are special kind of values that allow the synchronisation of different processes. Futures are in fact identifiers for promised results of function calls that are still awaited. When the result is necessary for the computation, the process is blocked until the result is returned. We are interested in this paper in transparent first-class futures, and their use within distributed components. We say that futures are transparent if the result is automatically and implicitly awaited upon the first access to the value; and that futures are first-class if they can be transmitted between components as usual objects. Thus, because of the difficulty to identify future objects, analysing the behaviour of omponents using first-class transparent futures is challenging. This paper contributes with first a static representation for futures, second a means to detect local deadlocks in a component system with first class futures, and finally extensions to interface definitions in order to avoid such deadlocks

Modélisation et analyse de systèmes asynchrones avec CADP

La conception des systèmes industriels critiques comportant du parallélisme asynchrone nécessite l'utilisation de méthodes formelles, assistées par des outils de vérification adaptés, afin de détecter et corriger les erreurs le plus tôt possible. Dans ce rapport, nous illustrons l'emploi de la boîte à outils CADP pour la modélisation et la vérification formelle de tels systèmes, à travers l'exemple d'une unité dédiée au perçage des pièces métalliques. Nous décrivons en langage LOTOS deux versions différentes de l'unité, régies par un contrôleur principal séquentiel, respectivement parallèle. Ensuite, nous effectuons la génération et la minimisation des deux espaces d'états sous-jacents, ainsi que l'inspection visuelle de celui, plus petit, correspondant à la version équipée du contrôleur séquentiel. Finalement, nous analysons le comportement des deux versions de l'unité de perçage en employant deux méthodes de vérification complémentaires, basées sur les bisimulations (equivalence checking) et les logiques temporelles (model checking)

CAESAR_SOLVE: A Generic Library for On-the-Fly Resolution of Alternation-Free Boolean Equation Systems

Boolean Equation Systems (BESs) provide a useful framework for modeling various verification problems on finite-state concurrent systems, such as equivalence checking and model checking. These problems can be solved on-the-fly (i.e., without constructing explicitly the state space of the system under analysis) by using a demand-driven construction and resolution of the corresponding BES. In this report, we present a generic software library dedicated to on-the-fly resolution of alternation-free BESs (i.e., without mutually recursive minimal and maximal fixed point equations). Four resolution algorithms are currently provided by the library: algorithms A1 and A2 are general, the latter being optimized to produce small-depth diagnostics, whereas algorithms A3 and A4 are specialized for handling acyclic and disjunctive/conjunctive BESs in a memory-efficient way. The library is developed within the CADP verification toolbox using the generic OPEN/CAESAR environment and is currently used for three purposes: on-the-fly equivalence checking modulo five widely-used equivalence relations, on-the-fly model checking of regular alternation-free mu-calculus, and on-the-fly reduction of state spaces based on tau-confluence

Efficient diagnostic generation for boolean equation systems

Theme 1 - Reseaux et systemes - Projet VASYSIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.2000 n.3861 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc