Jean-Christophe Dubacq

Kolmogorov complexity and cellular automata classification

We present a new approach to cellular automata (CA) classification based on algorithmic complexity. We construct a parameter ? which is based only on the transition table of CA and measures the “randomness” of evolutions; ? is better, in a certain sense, than any other parameter recursively definable on CA tables. We investigate the relations between the classical topological approach and ours. Our parameter is compared with Langtons ? parameter: ? turns out to be theoretically better and also agrees with some practical evidences reported in literature. Finally, we propose a protocol to approximate ? and make experiments on CA dynamical behavior.

Signals for Cellular Automata in Dimension 2 or Higher

We investigate how increasing the dimension of the array can help to draw signals on cellular automata. We show the existence of a gap of constructible signals in any dimension. We exhibit two cellular automata in dimension 2 to show that increasing the dimension allows to reduce the number of states required for some constructions.

A publication-subscription interaction schema for desktop grid computing

This paper proposes a Publish-Subscribe framework for the design of Desktop Grid (DG) middleware. This work focuses on a modeling and a verification of a DG protocol based on the Publish-Subscribe paradigm and introduces a prototype that we are currently developing. Our prototype implementation is based on Redis, a key-value no-SQL Web 2.0 tool with Publish-Subscribe functionality. Whereas most previous approaches required to build a number of layers before the layer of the DG middleware, we have only one layer in our system. In addition, our system is characterized to be light in terms of coding lines and used resources. It is therefore very convenient to implement DGs on resource constrained systems, e.g. tablets and smartphones.

Methods for partitioning data to improve parallel execution time for sorting on heterogeneous clusters

The aim of the paper is to introduce general techniques in order to optimize the parallel execution time of sorting on a distributed architectures with processors of various speeds. Such an application requires a partitioning step. For uniformly related processors (processors speeds are related by a constant factor), we develop a constant time technique for mastering processor load and execution time in an heterogeneous environment and also a technique to deal with unknown cost functions. For non uniformly related processors, we use a technique based on dynamic programming. Most of the time, the solutions are in

Analysis of Peer-to-Peer Protocols Performance for Establishing a Decentralized Desktop Grid Middleware

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Practical Security in Distributed Systems

(p) (p is the number of processors), independent of the problem size n. Consequently, there is a small overhead regarding the problem we deal with but it is inherently limited by the knowing of time complexity of the portion of code following the partitioning.