Team Pop Art

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Overall Objectives
Scientific Foundations
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Software
New Results
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Section: New Results

Other results

Programming models and calculi

Participant : P. Fradet.

We have been interested for a long time in formal calculi in order to study programming language issues in the simplest possible setting. We present here work within the $ \lambda$ -calculus (compilation of higher-order sequential languages) and the $ \gamma$ -calculus (higher-order parallel and non-deterministic programming).

$ \lambda$ -calculus and the Krivine abstract machine

The Krivine machine is a simple and natural implementation of the call-by-name $ \lambda$ -calculus. While its original description has remained unpublished, this machine has served as a basis for many variants, extensions and theoretical studies. We have presented the Krivine machine and some well-known variants in a common framework  [Oops!] . We have characterized the essence of the Krivine machine and have located it in the design space of functional language implementations. This work is based on the framework that we had previously developed for the systematic study of functional language implementations  [49] .

This is joint work with Rémi Douence from the Obasco project team (École des Mines de Nantes).

$ \gamma$ -calculus and higher-order chemical programming

The chemical reaction metaphor describes computation in terms of a chemical solution in which molecules (representing data) interact freely according to reaction rules. Formally, chemical programs can be represented as associative-commutative rewritings (reactions) of multisets (chemical solutions).

This model of computation is well-suited to the specification of complex computing infrastructures. In particular, the orderless interactions between elements that occur in large parallel or open systems are naturally expressed as reaction rules.

We have been working on the application of Hocl to the programming of distributed applications, in particular to autonomic systems  [Oops!] . We have shown that autonomicity features ( e.g. , self-healing, self-protection, self-optimization, etc.) are naturally expressed as reaction rules.

This work is conducted in collaboration with Jean-Pierre Banâtre and Yann Radenac from the Paris project team at Irisa . It was the central topic of Yann Radenac's PhD thesis. This line of research is related to the AutoCHEM project (see section  8.2.1 ) starting this year.

Component-based modeling and analysis of genetic networks

Participants : G. Goessler [ contact person ] , A. Richard.

Genetic regulatory networks usually encompass a large number of genes, proteins, and metabolites. Being able to model and analyze its behavior is crucial for understanding the interactions between the proteins, and their functions. There has been a wide variety of modeling approaches, including the influential early work of [76] based on logical equations, and [54] based on differential equations. However, simulation and verification of the continuous model are expensive, and many properties are not even decidable in this framework. The approach of [48] based on the approximation of nonlinear models by piecewise linear differential inclusions, uses a discrete abstraction preserving the qualitative dynamics of networks. As [48] approximates the continuous behavior with a monolithic discrete transition system, it still suffers from state space explosion. This problem has been addressed with the component-based approach of [55] where the discrete abstraction is constructed and analyzed modularly, allowing to deal with complex, high-dimensional systems. We have further improved this technique by allowing for a more precise, conservative abstraction.

Using the same approach, we are currently studying, in cooperation with H. de Jong (Helix) and G. Batt (Contraintes), the definition of a symbolic representation of the network behavior as a compact exchange format between the Genetic Network Analyzer (GNA) developed in the Helix group, and the model cheker CADP developed by Vasy.

The lack of numerical values for the parameters characterizing the interactions of a genetic regulatory network makes classical numerical analysis techniques difficult to apply. The approach of [48] defines a discrete abstraction preserving the qualitative dynamics of networks for wide ranges of parameter values. We have developed, in cooperation with H. de Jong, a novel algorithm to enumerate all classes of parameter values of an incompletely specified network. This technique has been implemented and applied to the analysis of a model of a network controlling the stress response of bacteria, and has allowed to uncover a shortcoming in the model.

Interactions Between Law and Information and Communication Sciences

Participant : D. Le Métayer [ contact person ] .

Daniel Le Métayer is initiating a new activity (which is to become an independent action in the short term) on the interactions between ICT (Information and Communication Technologies) and law. The motivation for this activity is the observation that the impact of ICT on the every day life of most individuals raises new challenges which cannot be tackled by a purely technological approach. Our position is that the first step for a fruitful and useful exploration of the relationship between the legal and technical dimensions is the definition of a formal framework for expressing the notions at hand, understanding them without ambiguity, and eventually relating or combining them. The first application of this approach, which is conducted within the PRIAM ARC, concerns privacy protection in the “ambient intelligence” context. Privacy is a complex issue, especially in the context of ambient intelligence, both from the legal and the technical perspective:

The PRIAM project emphasizes the design of privacy policies that are amenable to both a formal description and a realistic implementation in the ambient world. The techniques under study are based on a combination of a priori controls ( e.g. , access controls), which are the most conservative, and a posteriori controls ( e.g. , audits) which may be easier to enforce on resource-constrained devices.

Control for data-parallel systems

Participant : E. Rutten.

Data intensive computing is increasingly getting high importance in a wide range of scientific and engineering domains. Such systems manipulate large amounts of data; so high performance, scalability and throughput are important requirements. Reconfigurability is another interesting feature because it makes the systems flexible enough to be adapted to various environment and resource constraints. The Gaspard2 (http://www.lifl.fr/west/gaspard )development framework aims at proposing a solution to the design of data intensive applications in general, and high-performance embedded system-on-chip (SoCs) in particular.

We have proposed a synchronous model of Gaspard2 , in order to bridge the gap between Gaspard2 and analysis and verification tools of the synchronous technology so that formal validation is favored [Oops!] .

The automation of the transformations is implemented within an MDE framework [Oops!] .

We extend Gaspard2 , by adding reactive control features based on finite state machines [Oops!] , [Oops!] , and are integrating this extension in the synchronous model.

This work is conducted in cooperation with the DaRT project at UR Futurs in Lille.


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