Proving a Petri net model-checker implementation

Petri nets are a widely used tool in verification through model-checking. In this approach, a Petri Net model of the system of interest is produced and its reachable states are computed, searching for erroneous executions. Compilation of such a Petri net model is one way to accelerate its verification. It consists in generating code to explore the reachable states of the considered Petri net, which avoids the use of a fixed exploration tool involving an "interpretation" of the Petri net structure. In this paper, we show how to compile Petri nets targeting the LLVM language (a high-level assembly language) and formally prove the correct-ness of the produced code. To this aim, we define a structural operational semantics for the fragment of LLVM we use. The acceleration obtained from the presented compilation techniques has been evaluated in [6]

Compilation de réseaux de Petri (modèles haut niveau et symétries de processus)

Cette thèse s'intéresse à la vérification de systèmes automatisables par model-checking. La question sous-jacente autour de laquelle se construit la contribution est la recherche d'un compromis entre différents objectifs potentiellement contradictoires : la décidabilité des systèmes à vérifier, l'expressivité des formalismes de modélisation, l'efficacité de la vérification, et la certification des outils utilisés. Dans ce but, on choisit de baser la modélisation sur des réseaux de Petri annotés par des langages de programmation réels. Cela implique la semi-décidabilité de la plupart des questions puisque la responsabilité de la terminaison est remise entre les mains du modélisateur (tout comme la terminaison des programmes est de la responsabilité du programmeur). Afin d'exploiter efficacement ces annotations, on choisit ensuite une approche de compilation de modèle qui permet de générer des programmes efficaces dans le langage des annotations, qui sont alors exécutées de la manière la plus efficace. De plus, la compilation est optimisée en tirant partie des spécificités de chaque modèle et nous utilisons l'approche de model-checking explicite qui autorise cette richesse d'annotations tout en facilitant le diagnostique et en restant compatible avec la simulation (les modèles compilés peuvent servir à de la simulation efficace). Enfin, pour combattre l'explosion combinatoire, nous utilisons des techniques de réductions de symétries qui permettent de réduire les temps d'exploration et l'espace mémoire nécessaire.This work focuses on verification of automated systems using model-checking techniques. We focus on a compromise between potentially contradictory goals: decidability of systems to be verified, expressivity of modeling formalisms, efficiency of verification, and certification of used tools. To do so, we use high level Petri nets annotated by real programming languages. This implies the semi-decidability of most of problems because termination is left to the modeler (like termination of programs is left to the programmer). To handle these models, we choose a compilation approach which produces programs in the model annotation language, this allows to execute them efficiently. Moreover, this compilation is optimizing using model peculiarities. However, this rich expressivity leads to the use of explicit model-checking which allows to have rich model annotations but also allows to easily recover errors from verification, and remains compatible with simulation (these compiled models can be used for efficient simulation). Finally, to tackle the state space explosion problem, we use reduction by symmetries techniques which allow to reduce exploration times and state spaces.EVRY-Bib. électronique (912289901) / SudocSudocFranceF

Web Report on the Model Checking Contest @ Petri Net 2013

http://mcc.lip6.f

Compilation of Petri nets : high-level models and process symmetries

Cette thèse s'intéresse à la vérification de systèmes automatisables par model-checking. La question sous-jacente autour de laquelle se construit la contribution est la recherche d'un compromis entre différents objectifs potentiellement contradictoires : la décidabilité des systèmes à vérifier, l'expressivité des formalismes de modélisation, l'efficacité de la vérification, et la certification des outils utilisés. Dans ce but, on choisit de baser la modélisation sur des réseaux de Petri annotés par des langages de programmation réels. Cela implique la semi-décidabilité de la plupart des questions puisque la responsabilité de la terminaison est remise entre les mains du modélisateur (tout comme la terminaison des programmes est de la responsabilité du programmeur). Afin d'exploiter efficacement ces annotations, on choisit ensuite une approche de compilation de modèle qui permet de générer des programmes efficaces dans le langage des annotations, qui sont alors exécutées de la manière la plus efficace. De plus, la compilation est optimisée en tirant partie des spécificités de chaque modèle et nous utilisons l'approche de model-checking explicite qui autorise cette richesse d'annotations tout en facilitant le diagnostique et en restant compatible avec la simulation (les modèles compilés peuvent servir à de la simulation efficace). Enfin, pour combattre l'explosion combinatoire, nous utilisons des techniques de réductions de symétries qui permettent de réduire les temps d'exploration et l'espace mémoire nécessaire.This work focuses on verification of automated systems using model-checking techniques. We focus on a compromise between potentially contradictory goals: decidability of systems to be verified, expressivity of modeling formalisms, efficiency of verification, and certification of used tools. To do so, we use high level Petri nets annotated by real programming languages. This implies the semi-decidability of most of problems because termination is left to the modeler (like termination of programs is left to the programmer). To handle these models, we choose a compilation approach which produces programs in the model annotation language, this allows to execute them efficiently. Moreover, this compilation is optimizing using model peculiarities. However, this rich expressivity leads to the use of explicit model-checking which allows to have rich model annotations but also allows to easily recover errors from verification, and remains compatible with simulation (these compiled models can be used for efficient simulation). Finally, to tackle the state space explosion problem, we use reduction by symmetries techniques which allow to reduce exploration times and state spaces

Compilation de réseaux de Petri : modèles haut niveau et symétries de processus

This work focuses on verification of automated systems using model-checking techniques. We focus on a compromise between potentially contradictory goals: decidability of systems to be verified, expressivity of modeling formalisms, efficiency of verification, and certification of used tools. To do so, we use high level Petri nets annotated by real programming languages. This implies the semi-decidability of most of problems because termination is left to the modeler (like termination of programs is left to the programmer). To handle these models, we choose a compilation approach which produces programs in the model annotation language, this allows to execute them efficiently. Moreover, this compilation is optimizing using model peculiarities. However, this rich expressivity leads to the use of explicit model-checking which allows to have rich model annotations but also allows to easily recover errors from verification, and remains compatible with simulation (these compiled models can be used for efficient simulation). Finally, to tackle the state space explosion problem, we use reduction by symmetries techniques which allow to reduce exploration times and state spaces.Cette thèse s'intéresse à la vérification de systèmes automatisables par model-checking. La question sous-jacente autour de laquelle se construit la contribution est la recherche d'un compromis entre différents objectifs potentiellement contradictoires : la décidabilité des systèmes à vérifier, l'expressivité des formalismes de modélisation, l'efficacité de la vérification, et la certification des outils utilisés. Dans ce but, on choisit de baser la modélisation sur des réseaux de Petri annotés par des langages de programmation réels. Cela implique la semi-décidabilité de la plupart des questions puisque la responsabilité de la terminaison est remise entre les mains du modélisateur (tout comme la terminaison des programmes est de la responsabilité du programmeur). Afin d'exploiter efficacement ces annotations, on choisit ensuite une approche de compilation de modèle qui permet de générer des programmes efficaces dans le langage des annotations, qui sont alors exécutées de la manière la plus efficace. De plus, la compilation est optimisée en tirant partie des spécificités de chaque modèle et nous utilisons l'approche de model-checking explicite qui autorise cette richesse d'annotations tout en facilitant le diagnostique et en restant compatible avec la simulation (les modèles compilés peuvent servir à de la simulation efficace). Enfin, pour combattre l'explosion combinatoire, nous utilisons des techniques de réductions de symétries qui permettent de réduire les temps d'exploration et l'espace mémoire nécessaire

Building Petri nets tools around Neco compiler

International audienceThis paper presents Neco that is a Petri net compiler: it takes a Petri net as its input and produces as its output an optimised library to e ciently explore the state space of this Petri net. Neco is also able to work with LTL formulae and to perform model-checking by using SPOT library. We describe the components of Neco, and in particular the exploration libraries it produces, with the aim that one can use Neco in one's own projects in order to speedup Petri nets executions

Proving a Petri net model-checker implementation

Petri nets are a widely used tool in verification through model-checking. In this approach, a Petri Net model of the system of interest is produced and its reachable states are computed, searching for erroneous executions. Compilation of such a Petri net model is one way to accelerate its verification. It consists in generating code to explore the reachable states of the considered Petri net, which avoids the use of a fixed exploration tool involving an "interpretation" of the Petri net structure. In this paper, we show how to compile Petri nets targeting the LLVM language (a high-level assembly language) and formally prove the correct-ness of the produced code. To this aim, we define a structural operational semantics for the fragment of LLVM we use. The acceleration obtained from the presented compilation techniques has been evaluated in [6]

Optimising the compilation of Petri net models

International audienceCompilation of a Petri net model is one way to accelerate its veri cation through state space exploration. In this approach, code to explore the Petri net is generated, which avoids the use a xed exploration tool involving an interpretation" of the Petri net structure. In this paper, we show how peculiarities in the model (like places types, boundedness, invariants, etc., known by construction if adequate modelling tools are used) can be exploited to improve the generated code e ciency. We present a lightweight code generation framework targeting the LLVM language and demonstrate its exibility by considering several kinds of optimisations. Our compiler is called lightweight because the annotations of the compiled models are directly expressed in the target language, which saves from translating them and allows for fast compilation. The accelerations resulting from the optimisations are then evaluated on various Petri net models, showing important speedups and in some cases outperforming state-of-the-art tools

Model-Checking Real-Time Properties of an Aircraft Landing Gear System Using Fiacre

International audienceWe describe our experience with modeling the landing gear system of an aircraft using the formal specification language Fiacre. Our model takes into account the behavior and timing properties of both the physical parts and the control software of this system. We use this formal model to check safety and real-time properties on the system but also to find a safe bound on the maximal time needed for all gears to be down and locked (assuming the absence of failures). Our approach ultimately relies on the model-checking tool Tina, that provides state-space generation and model-checking algorithms for an extension of Time Petri Nets with data and priorities