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Nombre de programmes trouvés : 538
Conférences

le (1h30m40s)

BATTRE LA NASA ? IMPOSSIBLE ?

La NASA (l'agence spatiale des États-Unis) domine toutes les agences spatiales du monde de par la nature, le volume, et le niveau de ses programmes. On l'admire pour ses prouesses, son esprit pionnier, son ambition d'atteindre les horizons inconnus. L'avalanche de découvertes qu'elle a déclenchée nous excite, nous enchante et fait rêver d'au-delàs régulièrement repoussés. Et pourtant, cette énorme machine à découvertes n'est pas invincible.La conférence offre en exemple l'approche suivie par l'Europe, et avec elle l'Agence spatiale européenne (ESA) et ses états membres, qui l'ont ...
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Conférences

le (1h39m41s)

MARS EXPRESS, ROSETTA, HAYABUSA, EXOMARS, MMX : LA QUÊTE SPATIALE DE « L'ÉMERGENCE » DE LA VIE ENTRE DANS UNE NOUVELLE ÈRE

L'exploration spatiale du système solaire bouscule en profondeur des paradigmes parfois ancestraux, quant à notre conception de la formation et de l'évolution des mondes planétaires. À quelles échelles, dans l'espace et le temps, l'unicité de la Terre et de la vie qu'elle porte prennent-elles sens ? Quelle est la part relative de la contingence et de la généricité, dans les processus responsables des évolutions qui ont conduit à l'extraordinaire diversité qui se révèle à nous aujourd'hui ? Tel est le cadre dans lequel nous discuterons des ...
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Conférences

le (50m57s)

Point processes, cost and the growth of rank for locally compact groups (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

The cost of a vertex transitive graph is the infimum of the expected degree of an invariant random wiring of the graph. Similarly, one can define the cost of a point process on a homogeneous space, as the infimum of the average degree of a factor wiring on its points. It turns out that the cost of a Poisson process is maximal among point processes of the same density, by proving that all free processes weakly contain the Poisson. The cost is related to the growth ...
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Conférences

le (43m18s)

Spectral embedding for graph classification (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

Learning on graphs requires a graph feature representation able to discriminate among different graphs while being amenable to fast computation. The graph isomorphism problem tells us that no fast representation of graphs is known if we require the representation to be both invariant to nodes permutation and able to discriminate two non-isomorphic graphs. Most graph representations explored so far require to be invariant. We explore new graph representations by relaxing this constraint. We present a generic embedding of graphs relying on spectral graph theory ...
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Conférences

le (39m53s)

Emergence of extended states at zero in the spectrum of sparse random graphs (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

We confirm the long-standing prediction that c=e≈2.718 is the threshold for the emergence of a non-vanishing absolutely continuous part (extended states) at zero in the limiting spectrum of the Erdős-Renyi random graph with average degree c. This is achieved by a detailed second-order analysis of the resolvent (A−z)−1 near the singular point z=0, where A is the adjacency operator of the Poisson-Galton-Watson tree with mean offspring c. More generally, our method applies to arbitrary unimodular Galton-Watson trees, yielding explicit criteria for the presence or ...
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Conférences

le (1h1m15s)

On the modified Palm version (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

The Palm version of a stationary random measure is an important tool in probability. It is however not well known that there are in fact two Palm versions, with related but different interpretations. For lack of better terms, call the well known version standard and the less known version modified. In this talk we shall focus on the modified Palm version and its interpretation. The concepts of shift-coupling and mass-stationarity will play a key role
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Conférences

le (55m56s)

A notion of entropy for limits of sparse marked graphs (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

Bordenave and Caputo (2014) defined a notion of entropy for probability distributions on rooted graphs with finite expected degree at the root. When such a probability distribution \rho has finite BC entropy \Sigma(\rho), the growth in the number of vertices n of the number of graphs on n vertices whose associated rooted graph distribution is close to \rho is as d/2 n \log n + \Sigma(\rho) n + o(n), where d is expected degree of the root under \rho. We develop the parallel result for probability distributions on marked rooted graphs. Our graphs have vertex marks drawn from a finite ...
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Conférences

le (59m49s)

Sampling cluster point processes: a review (workshop ERC Nemo Processus ponctuels et graphes aléatoires unimodulaires)

The theme of this talk is the sampling of cluster and iterated cluster point processes. It is partially a review, mainly of the Brix–Kendall exact sampling method for cluster point processes and its adaptation by Moller and Rasmussen to Hawkes branching point processes on the real line with light-tail fertility rate. A formal proof via Laplace transforms of the validity of the method in terms of general clusters that are not necessarily point processes fits this purpose and allows to include the exact sampling of Boolean ...
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