A Survey of Desynchronization in a Polychronous Model of Computation

AbstractThe synchronous hypothesis arose in the late Eighties as a conceptual framework for the computer-aided design of embedded systems. Along with this framework, the issue of desynchronization was simultaneously raised as the major topic of mapping the ideal communication and computation model of synchrony on realistic and distributed computer architectures.The aim of the present article is to survey the development of this topics in the particular yet promising model of one of the prominent environments that were build along these principles: Signal and its polychronous (synchronous multi-clocked) model of computation, before to give some hints and ideas about ongoing research addressing this issue

La copie hâtive des Proverbes moraux

Relié à l’Abbaye de Saint-Victor dans un volume contenant divers ouvrages moraux, un manuscrit en papier des Proverbes Moraux de Christine de Pizan, BnF fr. 24864, soulève différentes questions, tout en résolvant celle de la date de composition de l’ouvrage : 17 oct. 1405. Comportant de nombreuses erreurs, ce témoin transmet aussi plusieurs leçons qui sont supérieures à celles conservées dans les manuscrits de présentation ; certaines de ces variantes se retrouvent dans des manuscrits qui ne sont pas associés avec l’atelier de Christine. Il paraît donc que Christine aurait fait circuler une version préliminaire et défectueuse des Proverbes. D’ailleurs, on pourrait se demander si les Proverbes moraux seraient non une composition originale, mais une copie de maximes déjà en circulation.Bound at the Abbey of Saint-Victor into a volume containing numerous other moral works, an early paper copy of Christine de Pizan’s Moral Proverbs, BnF fr. 24864, raises intriguing questions, while at the same time solving the question of the work’s date of composition (Oct. 17, 1405). While it contains many obvious errors, the manuscript also has a number of variants that are superior to those transmitted in the presentation copies, and that, moreover, are found in manuscripts not associated with Christine’s workshop. It would appear, then, that Christine distributed a preliminary, defective version of the Proverbs independently. One might also wonder whether the Moral Proverbs are not an original composition, but a copy of maxims already in circulation

Modular interpretation of heterogeneous modeling diagrams into synchronous equations using static single assignment

The ANR project SPACIFY develops a domain-specific programming environment, Synoptic, to engineer embedded software for space applications. Synoptic is an Eclipse-based modeling environment which supports all aspects of aerospace software design. As such, it is a domain-specific environment consisting of heterogeneous modeling and programming principles defined in collaboration with the industrial partners and end users of the project : imperative synchronous programs, data-flow diagrams, mode automata, blocks, components, scheduling, mapping and timing. This article focuses on the essence and distinctive features of its behavioral or programming aspects : actions, flows and automata, for which we use the code generation infrastructure of the synchronous modeling environment SME. It introduces an efficient method for transforming a hierarchy of blocks consisting of actions (sequential Esterel-like programs), data-flow diagrams (to connect and time modules) and mode automata (to schedule or mode blocks) into a set of synchronous equations. This transformation minimizes the needed state variables and block synchronizations. It consists of an inductive static-single assignment transformation algorithm across a hierarchy of blocks that produces synchronous equations. The impact of this new transformation technique is twofold. With regards to code generation objectives, it minimizes the needed resynchronization of each block in the system with respects to its parents, potentially gaining substantial performance from way less synchronizations. With regards to verification requirements, it minimizes the number of state variables across a hierarchy of automata and hence maximizes model checking performances

Compositional design of isochronous systems

International audienceThe synchronous modeling paradigm provides strong correctness guarantees for embedded system design while requiring minimal environmental assumptions. In most related frameworks, global execution correctness is achieved by ensuring the insensitivity of (logical) time in the program from (real) time in the environment. This property, called endochrony or patience, can be statically checked, making it fast to ensure design correctness. Unfortunately, it is not preserved by composition, which makes it difficult to exploit with component-based design concepts in mind. Compositionality can be achieved by weakening this objective, but at the cost of an exhaustive state-space exploration. This raises a trade-off between performance and precision. Our aim is to balance it by proposing a formal design methodology that adheres to a weakened global design objective: the non-blocking composition of weakly endochronous processes, while preserving local design objectives for synchronous modules. This yields an effective and cost-efficient approach to compositional synchronous modeling

Polychronous Interpretation of Synoptic, a Domain Specific Modeling Language for Embedded Flight-Software

The SPaCIFY project, which aims at bringing advances in MDE to the satellite flight software industry, advocates a top-down approach built on a domain-specific modeling language named Synoptic. In line with previous approaches to real-time modeling such as Statecharts and Simulink, Synoptic features hierarchical decomposition of application and control modules in synchronous block diagrams and state machines. Its semantics is described in the polychronous model of computation, which is that of the synchronous language Signal.Comment: Workshop on Formal Methods for Aerospace (FMA 2009

Manuscrits copiés en série

This article makes a detailed comparison of the four surviving copies of the Livre desfais et bonnes meurs du sage roy Charles V that were prepared under Christine de Pizan’s supervision: Paris, BnF fr. 5025 and 10153, Modena, Biblioteca Estense α.N.8.7 and Vatican City, Vat. Reg. lat. 920. The similarities and differences among the copies allow one to draw some conclusions about work practices in the author’s atelier.Cet article présente une comparaison détaillée des quatre exemplaires survivants du Livre des fais et bonnes meurs du sage roy Charles V préparés sous la direction de l’auteur: Paris, BnF fr. 5025 et 10153, Modena, Biblioteca Estense α.N.8.7 et Città del Vaticano, Vat. Reg. lat. 920. Les similitudes et divergences qu’on observe dans ces quatre témoins permettent de formuler quelques conclusions concernant les pratiques de travail dans l’atelier de Christine de Pizan

SPaCIFY: a Formal Model-Driven Engineering for Spacecraft On-Board Software

International audienceThe aim of this article is to present a model- driven approach proposed by the SPaCIFY project for spacecraft on-board software development. This ap- proach is based on a formal globally asynchronous lo- cally synchronous language called Synoptic, and on a set of transformations allowing code generation and model verification

Les origines des règles de l'art : une première enquête

Ouy Gilbert, Ouy-Parczewska Krystyna. Les origines des règles de l'art : une première enquête. In: Annales. Économies, Sociétés, Civilisations. 27ᵉ année, N. 6, 1972. pp. 1264-1316