Papers by Benoît Caillaud
Springer eBooks, 2017
In this short note, we establish a link between the theory of Moore Interfaces proposed in 2002 b... more In this short note, we establish a link between the theory of Moore Interfaces proposed in 2002 by Chakraborty et al. as a specification framework for synchronous transition systems, and the Assume/Guarantee contracts as proposed in 2007 by Benveniste et al. as a simple and flexible contract framework. As our main result we show that the operation of saturation of A/G contracts (namely the mapping (A, G) → (A, G∨¬A)), which was considered a drawback of this theory, is indeed implemented by the Moore Game of Chakraborty et al. We further develop this link and come up with some remarks on Moore Interfaces.
HAL (Le Centre pour la Communication Scientifique Directe), Feb 18, 2022
Since its 3.3 release, Modelica offers the possibility to specify models of dynamical systems wit... more Since its 3.3 release, Modelica offers the possibility to specify models of dynamical systems with multiple modes having different DAE-based dynamics. However, the handling of such models by the current Modelica tools is not satisfactory, with mathematically sound models yielding exceptions at runtime. In this report, we illustrate this behavior on several small-sized examples, shedding light on the shortcomings of the approximate structural analysis implemented in current Modelica tools. To address part of these issues, we propose a systematic transformation process for multimode Modelica models, based on the results of an already implemented multimode structural analysis, that guarantees that the output Modelica model is correctly compiled by state-of-the-art Modelica tools. Still, this transformation is limited to models that do not exhibit impulsive behaviors at mode changes: the remaining issues illustrated by our introductory examples can only be solved by a structural analysis of mode changes, coupled with a specific handling of impulsive variables. We address these points in this report by proposing, first, a structural analysis method able to handle modes and mode changes in a unified framework, and second, a compile-time identification and characterization of impulsive variables. Implementations of both methods, based on efficient symbolic representations and algorithms, are in the works.
Springer eBooks, 2019
Our objective is to model and simulate Cyber-Physical Systems (CPS) such as robots, vehicles, and... more Our objective is to model and simulate Cyber-Physical Systems (CPS) such as robots, vehicles, and power plants. The structure of CPS models may change during simulation due to the desired operation, due to failure situations or due to changes in physical conditions. Corresponding models are called multi-mode. We are interested in multidomain, component-oriented modeling as performed, for example, with the modeling language Modelica that leads naturally to Differential Algebraic Equations (DAEs). This paper is thus about multi-mode DAE systems. In particular, new methods are discussed to overcome one key problem that was only solved for specific subclasses of systems before: How to switch from one mode to another one when the number of equations may change and variables may exhibit impulsive behavior? An evaluation is performed both with the experimental modeling and simulation system Modia, a domain specific language extension of the programming language Julia, and with SunDAE, a novel structural analysis library for multi-mode DAE systems.
Formal Methods in System Design, Mar 1, 2006
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
HAL (Le Centre pour la Communication Scientifique Directe), Dec 23, 2013
Projet BGLE 2 Sys2soft -D3.1 1 Type-based Causality Analysis in Hybrid Modelers 1 Synthèse 1.1 Id... more Projet BGLE 2 Sys2soft -D3.1 1 Type-based Causality Analysis in Hybrid Modelers 1 Synthèse 1.1 Identification du projet Programme BGLE 2 Projet (Acronyme) Sys2soft Date de commencement 1er juin 2012 Date d'achèvement 30 novembre 2015 Une question centrale dans la conception des langages de modélisation des systèmes hybrides, y compris Modelica, est la détection, à la compilation, des circuits algébriques ou boucles de causalité. De tels circuits provoquent le blocage du modèle lors de sa simulation et empêchent la génération de code ordonancé statiquement. Ce livrable détaille une solution à ce problème, pour un langage de modélisation hybride qui combine des equations de flots à la Lustre et des equations diffé r e n t i e l l e s o r d i n a i r e s . L e langage comporte un opérateur last(x)don tlav aleurestlalimiteàgauc hedelav ariable x. Cet opérateur permet de casser des circuits algébriques et a l'avantage de s'appliquer indifféremment sur des variables discretes ou continues. La sémantique du langage est à b a s e d e n o m b r e s r é e l s n o n -s t a n d a r d s e t d é fi n i t u n e e x é c u t i o n c o m m e u n e s u i t e d e p a s , progressant de manière infinitésimale. Un signal est considéré causalement correct quand il peut être calculé séquentiellement et est continu en dehors des instants où un pas de calcul discret a lieu. L'analyse de causalité est définie sous la forme d'un système d'inférence de type . Il est prouvé que dans tout programme correctement typé, les signaux sont continus en dehors des seuls instants où des calculs discrets ont lieu. Cette analyse de causalité permet de générer un code de simulation ordonnancé statiquement qui fait appel à une biblioth'eque standard de solveurs de systèmes déquations differentielles. La pertinance de cette approche est illustrée par plusieurs exemples écrits dans le langage Zélus, qui est un langage de modélisation des systèmes hybrides, qui combine des equations de flôts synchrones et des equations diffé r e n t i e l l e s .
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
HAL (Le Centre pour la Communication Scientifique Directe), Jul 9, 2013
Surgical process modeling aims at providing an explicit representation of surgical procedural kno... more Surgical process modeling aims at providing an explicit representation of surgical procedural knowledge. Surgical process models are inferred from a set of surgical procedure recordings, and represent in a concise manner concurrency, causality and conflict relations between actions. The paper presents preliminary results regarding the use of test and flip nets, a mild extension of flip-flop nets, to represent surgical process models. A test and flip net synthesis algorithm, based on linear algebraic methods in the Z/2Z ring is detailed. Experimental results regarding the use of this synthesis algorithm to automate the construction of simple surgical process models are also presented.
arXiv (Cornell University), Nov 7, 2008
In this paper, we present a probabilistic adaptation of an Assume/Guarantee contract formalism. F... more In this paper, we present a probabilistic adaptation of an Assume/Guarantee contract formalism. For the sake of generality, we assume that the extended state machines used in the contracts and implementations define sets of runs on a given set of variables, that compose by intersection over the common variables. In order to enable probabilistic reasoning, we consider that the contracts dictate how certain input variables will behave, being either non-deterministic, or probabilistic; the introduction of probabilistic variables leading us to tune the notions of implementation, refinement and composition. As shown in the report, this probabilistic adaptation of the Assume/Guarantee contract theory preserves compositionality and therefore allows modular reliability analysis, either with a top-down or a bottom-up approach.
HAL (Le Centre pour la Communication Scientifique Directe), Jul 27, 2015
In this paper we present a new method to perform the higher order sliding modes analysis of traje... more In this paper we present a new method to perform the higher order sliding modes analysis of trajectories of hybrid systems with chattering behavior. This method improves our previous work [AC15] as it modifies numerical simulation algorithms to make them compute the higher order terms of the normal unit vectors of the systems dynamics whenever the 1 st order sliding mode theory cannot be applied. Such modification does not affect the generality of our previous contribution in [AC15]. Our algorithm is general enough to handle both chattering on a single R n-1 switching manifold (i.e. chattering between two dynamics) as well as chattering on the intersection of finitely many intersected R n-1 switching manifolds. In this last case, we show by a special hierarchical application of convex combinations, that unique solutions can be found in general cases when the switching function takes the form of finitely many intersecting manifolds so that an efficient numerical treatment of the sliding motion constrained on the entire discontinuity region (including the switching intersection) is guaranteed. Illustrations of the techniques developed in this article are given on representative examples.
The Visual Computer, 2020
When defining virtual reality applications with complex procedures, such as medical operations or... more When defining virtual reality applications with complex procedures, such as medical operations or mechanical assembly or maintenance procedures, the complexity and the variability of the procedures makes the definition of the scenario difficult and time-consuming. Indeed, the variability complicates the definition of the scenario by the experts, and its combinatories demands a comprehension effort for the developer, which is often out of reach. Additionally, the experts have a hard time explaining the procedures with a sufficient level of details, as they usually forget to mention some actions that are, in fact, important for the application. To ease the creation of scenario, we propose a complete methodology, based on (1) an iterative process composed of: (2) the recording of actions in virtual reality to create sequences of actions, and (3) the use of mathematical tools that can generate a complete scenario from a few of those sequences, with (4) graphical visualization of the scenarios and complexity indicators. This process helps the expert to determine the sequences that must be recorded to obtain a scenario with the required variability.
Lecture Notes in Computer Science, 2015
When a project is realized in a globalized environment, multiple stakeholders from different orga... more When a project is realized in a globalized environment, multiple stakeholders from different organizations work on the same system. Depending on the stakeholders and their organizations, various (possibly overlapping) concerns are raised in the development of the system. In this context a Domain Specific Language (DSL) supports the work of a group of stakeholders who are responsible for addressing a specific set of concerns. This chapter identifies the open challenges arising from the coordination of globalized domain-specific languages. We identify two types of coordination: technical coordination and social coordination. After presenting an overview of the current state of the art, we discuss first the open challenges arising from the composition of multiple DSLs, and then the open challenges associated to the collaboration in a globalized environment.
Proceedings of the 4th ACM international conference on Embedded software, 2004
We present an extension of a mathematical framework proposed by the authors to deal with the comp... more We present an extension of a mathematical framework proposed by the authors to deal with the composition of heterogeneous reactive systems. Our extended framework encompasses diverse models of computation and communication such as synchronous, asynchronous, causality-based partial orders, and earliest execution times. We introduce an algebra of tag structures and morphisms between tag sets to define heterogeneous parallel composition formally and we use a result on pullbacks from category theory to handle properly the case of systems derived by composing many heterogeneous components. The extended framework allows us to establish theorems, from which design techniques for correct-by-construction deployment of abstract specifications can be derived. We illustrate this by providing a complete formal support for correct-by-construction distributed deployment of a synchronous design specification over an Ltta medium.
Lecture Notes in Computer Science, 2003
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Surgical process modeling aims at providing an explicit representation of surgical procedural kno... more Surgical process modeling aims at providing an explicit representation of surgical procedural knowledge. Surgical process models are inferred from a set of surgical procedure recordings, and represent in a concise manner concurrency, causality and conflict relations between actions. The paper presents preliminary results regarding the use of test and flip nets, a mild extension of flip-flop nets, to represent surgical process models. A test and flip net synthesis algorithm, based on linear algebraic methods in the Z/2Z ring is detailed. Experimental results regarding the use of this synthesis algorithm to automate the construction of simple surgical process models are also presented.
Lecture Notes in Computer Science, 2011
Interval Markov Chains (IMCs) are the base of a classic probabilistic specication theory by Larse... more Interval Markov Chains (IMCs) are the base of a classic probabilistic specication theory by Larsen and Jonsson in 1991. They are also a popular abstraction for probabilistic systems. In this paper we study complexity of several problems for this abstraction, that stem from compositional modeling methodologies. In particular we close the complexity gap for thorough renement of two IMCs and for deciding the existence of a common implementation for an unbounded number of IMCs, showing that these problems are EXPTIME-complete. We also prove that deciding consistency of an IMC is polynomial and discuss suitable notions of determinism for such specications.
Proceedings of the 5th ACM international conference on Embedded software - EMSOFT '05, 2005
Heterogeneity is a challenge to overcome in the design of embedded systems. We presented in the r... more Heterogeneity is a challenge to overcome in the design of embedded systems. We presented in the recent past a theory for the composition of heterogeneous components based on tagged systems, a behavioral (denotational) framework. in this paper, we present an operational view of tagged systems, where we focus on tag machines as mathematical artifacts that act as finitary generators of tagged systems. Properties of tag machines are investigated. A fundamental theorem on homogeneous compositionality is given as a first step towards an operational theory of heterogeneous systems. Categories and Subject Descriptors: C.3.3 [Specialpurpose and application-based systems]: Real-time and embedded systems.
Proceedings of the seventh ACM international conference on Embedded software, 2009
This paper presents a unification of interface automata and modal specifications, two radically d... more This paper presents a unification of interface automata and modal specifications, two radically dissimilar models for interface theories. Interface automata is a game-based model, which allows to make assumptions on the environment and propose an optimistic view for composition : two components can be composed if there is an environment where they can work together . Modal specification is a language theoretic account of a fragment of the modal mu-calculus logic that is more complete but which does not allow to distinguish between the environment and the component. Partial unifications of these two frameworks have been explored recently. A first attempt by Larsen et al. considers modal interfaces, an extension of modal specifications that deals with compatibility issues in the composition operator. However, this composition operator is incorrect. A second attempt by Raclet et al. gives a different perspective, and emphasises on conjunction and residuation of modal specifications, including when interfaces have dissimilar alphabets, but disregards interface compatibility. The present paper contributes a thorougher unification of the two theories by correcting the modal interface composition operator presented in the paper by Larsen et al., drawing a complete picture of the modal interface algebra, and pushing even further the comparison between interface automata, modal automata and modal interfaces.
Theoretical Computer Science, 2011
Notions of specification, implementation, satisfaction, and refinement, together with operators s... more Notions of specification, implementation, satisfaction, and refinement, together with operators supporting stepwise design, constitute a specification theory. We construct such a theory for Markov Chains (MCs) employing a new abstraction of a Constraint MC. Constraint MCs permit rich constraints on probability distributions and thus generalize prior abstractions such as Interval MCs. Linear (polynomial) constraints suffice for closure under conjunction (respectively parallel composition). This is the first specification theory for MCs with such closure properties. We discuss its relation to simpler operators for known languages such as probabilistic process algebra. Despite the generality, all operators and relations are computable.
Formal Aspects of Computing, 2002
The synthesis problem for Petri nets consists in deciding constructively the existence of a Petri... more The synthesis problem for Petri nets consists in deciding constructively the existence of a Petri net with sequential state graph isomorphic to a given graph. If events are attached to locations, one may set as an additional requirement that the synthesised net should be distributable; i.e. such that events at different locations have no common input place, whence distributed conflicts are avoided. Distributable nets are easily implemented by finite families of automata (one per location) communicating with each other by asynchronous message passing. We show that the general Petri net synthesis problem and its distributed version may both be solved in time polynomial in the size of the given graph. We report on some preliminary experiments of Petri net synthesis applied to the distribution of reactive automata using the tool synet.
Electronic Notes in Theoretical Computer Science, 2005
This paper proposes a merge operator for behavioral requirements expressed by Message Sequence Ch... more This paper proposes a merge operator for behavioral requirements expressed by Message Sequence Charts and shows how this product can be systematically used to integrate new behaviors in an existing one. First the merge operator is defined as a fibered product of scenario descriptions. This product is then used to integrate a consensus mechanism to solve the non-local choice problem.
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Papers by Benoît Caillaud