We consider a certain class of vectorial evolution equations, which are linear in the (max,+) semi-eld. They can be used to model several types of discrete event systems, in particular stochastic service systems where we assume that the arrival process of customers (tokens, jobs, etc.) is Poisson. Under natural Cramer type conditions on certain variables, we show that the expected waiting time ...

We study the size of the sets of gradients of bump functions on the Hilbert space `2, and the related question as to how small the set of tangent hyperplanes to a smooth bounded starlike body in `2 can be. We find that those sets can be quite small. On the one hand, the usual norm of the Hilbert space `2 can be uniformly approximated by C 1 smooth Lipschitz functions ψ so that the cones generat...

Global band selection or feature extraction methods have been applied to hyperspectral image classification to overcome the “curse of dimension”. We applied class-based feature extraction approaches and compressed the class data into different lower dimensional subspaces. Land cover classes in hyperspectral imagery could be roughly modelled as lowdimensional Gaussian clusters (i.e., “Gaussian p...

We study the problem of consistency checking for constraint networks over combined qualitative formalisms. We propose a framework which encompasses loose integrations, multiscale reasoning and a form of spatio-temporal reasoning. In particular, we identify sufficient conditions ensuring the polynomiality of consistency checking, and we use them to find tractable subclasses. MOTS-CLÉS : réseaux ...