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Nombre de programmes trouvés : 517
Conférences

le (52m52s)

Absence of percolation for Poisson outdegree-one graphs (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

A Poisson outdegree-one graph is a directed graph based on a marked Poisson point process such that each vertex has only one outgoing edge. We state the absence of percolation for such graphs satisfying two assumptions. The Shield assumption roughly says that the graph is locally determined with possible random horizons. The Loop assumption ensures that any forward branch merges on a loop provided that the Poisson point process is augmented with a finite collection of well-chosen points. This result allows to solve a ...
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Conférences

le (46m11s)

Central Limit theorem for quasi-local statistics of point processes with fast decay of correlations (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

We shall consider Euclidean stationary point processes which have fast decay of correlations i.e., their correlation functions factorize upto an additive error decaying exponentially in the separation distance. By a quasi-local statistic of the point process, we refer to statistics that can be expressed as sum of contributions from the points and the contribution of every point being determined by a random ball around the point whose radius has an exponential tail. There are many well-known point processes and statistics that satisfy these conditions ...
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Conférences

le (56m5s)

Eternal family trees and dynamics on unimodular random graphs (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

This talk is centered on covariant dynamics on unimodular random graphs and random networks (marked graphs), namely maps from the set of vertices to itself which are preserved by graph or network isomorphisms. Such dynamics are referred to as vertex-shifts here. These dynamics have point-shifts on point processes as a subclass. First we give a classification of vertex-shifts on unimodular random networks. Each such vertex-shift partitions the vertices into a collection of connected components and foils. The latter are discrete analogues the stable manifold ...
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Conférences

le (51m43s)

On the notion of dimension of unimodular discrete spaces (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

In this talk we will define notions of dimension for unimodular random graphs and point-stationary point processes. These notions are in spirit similar to the Minkowski dimension and the Hausdorff dimension. The key point in the definitions is the use of the mass transport principle which is used indispensably and distinguishes this view point from the previous notions which are defined in the literature. The connections of these definitions to volume growth and other notions of dimension are also discussed, which provide a toolset ...
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Conférences

le (43m39s)

A stable marriage between order and disorder (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

Stable matchings were introduced in a seminal paper by Gale and Shapley (1962) and play an important role in economics. Following closely Holroyd, Pemantle, Peres and Schramm (2009), we shall first discuss a few basic properties of stable matchings between two discrete point sets (resp. point processes) in Euclidean space, where the points prefer to be close to each other. For comparison we also discuss stable transports from Lebesgue measure to point processes. In the second part of the talk we consider a stable ...
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Conférences

le (53m51s)

Subdiffusivity of random walks on random planar maps, via stationarity (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

Random planar maps have been the subject of numerous studies over the last years. They are instance of stationary and reversible random planar maps exhibiting a non-conventional geometry at large scale. Because of their “fractal” geometry, the simple random walk on these random graphs is believed to be subdiffusive, i.e. it displaces slowler than in the regular grid case. We will propose an approach to such results strongly based on the stationary of these random graphs, i.e. the fact that their distributions is invariant under ...
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Conférences

le (14m47s)

Comment améliorer la qualité des images ?

On s'interesse ici à des détails inaccessibles dans l'image, parce que le détecteur est trop loin de la scène que l'on cherche à imager, comme par exemple en imagerie satellitaire pour l'observation de la terre, ou que l'on cherche des objets petits, comme en microscopie pour la biologie. On essaye d'améliorer numériquement la qualité de ces images et leurs résolutions.Laure BLANC-FERAUD a obtenu le prix Michel Montpetit-Inria 2013 en sciences mécaniques et informatiques, décerné par l’Académie des sciences.
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