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Results for "Vincent J. Hellendoorn"

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Are My Invariants Valid? A Learning ApproachMar 14 2019Ensuring that a program operates correctly is a difficult task in large, complex systems. Enshrining invariants -- desired properties of correct execution -- in code or comments can support maintainability and help sustain correctness. Tools that can ... More
Are My Invariants Valid? A Learning ApproachMar 14 2019Mar 15 2019Ensuring that a program operates correctly is a difficult task in large, complex systems. Enshrining invariants -- desired properties of correct execution -- in code or comments can support maintainability and help sustain correctness. Tools that can ... More
The pattern and process of gene family evolutionFeb 11 2011Large scale databases are available that contain homologous gene families constructed from hundreds of complete genome sequences from across the three domains of Life. Here we discuss approches of increasing complexity aimed at extracting information ... More
Stellar Mass Black Holes in Young GalaxiesJul 15 2011We explore the potential cumulative energy production of stellar mass black holes in early galaxies. Stellar mass black holes may accrete substantially from the higher density interstellar media of primordial galaxies, and their energy release would be ... More
Discrete transverse superconducting modes in nano-cylindersMay 20 2004Spatial variation in the superconducting order parameter becomes significant when the system is confined at dimensions well below the typical superconducting coherence length. Motivated by recent experimental success in growing single-crystal metallic ... More
Proper Motions of OH Masers and Magnetic Fields in Massive Star-Forming RegionsAug 08 2007We present data of proper motions of OH masers in the massive star-forming regions ON 1, K3-50, and W51 Main/South. OH maser motions in ON 1 are consistent with expansion at approximately 5 km/s, likely tracing the expanding ultracompact H II region. ... More
Full-Polarization Observations of OH Masers in Massive Star-Forming Regions: II. Maser Properties and the Interpretation of PolarizationJan 24 2006We analyze full-polarization VLBA data of ground-state, main-line OH masers in 18 massive star-forming regions previously presented in a companion paper. The OH masers often arise in the shocked neutral gas surrounding ultracompact Hii regions. Magnetic ... More
Large Magnetic Fields and Motions of OH Masers in W75 NNov 02 2006We report on a second epoch of VLBA observations of the 1665 and 1667 MHz OH masers in the massive star-forming region W75 N. We find evidence to confirm the existence of very strong (~40 mG) magnetic fields near source VLA 2. The masers near VLA 2 are ... More
Vibron-polaron critical localization in a finite size molecular nanowireMay 04 2004Sep 01 2004The small polaron theory is applied to describe the vibron dynamics in an adsorbed nanowire with a special emphasis onto finite size effects. It is shown that the finite size of the nanowire discriminates between side molecules and core molecules which ... More
Relaxation channels of two-vibron bound states in α-helix proteinsOct 15 2003Relaxation channels for two-vibron bound states in an anharmonic alpha-helix protein are studied. It is pointed out that the relaxation originates in the interaction between the dressed anharmonic vibrons and the remaining phonons. This interaction is ... More
Fast energy transfer mediated by multi-quanta bound states in a nonlinear quantum latticeMay 03 2006By using a Generalized Hubbard model for bosons, the energy transfer in a nonlinear quantum lattice is studied, with special emphasis on the interplay between local and nonlocal nonlinearity. For a strong local nonlinearity, it is shown that the creation ... More
On the global evolution problem in 2+1 gravityOct 10 1996Existence of global CMC foliations of constant curvature 3-dimensional maximal globally hyperbolic Lorentzian manifolds, containing a constant mean curvature hypersurface with $\genus(\Sigma) > 1$ is proved. Constant curvature 3-dimensional Lorentzian ... More
Vibron-polaron in alpha-helices. I. Single-vibron statesFeb 07 2005Sep 16 2005The vibron dynamics associated to amide-I vibrations in a 3D alpha-helix is described according to a generalized Davydov model. The helix is modeled by three spines of hydrogen-bonded peptide units linked via covalent bonds. To remove the intramolecular ... More
Escape Probability, Mean Residence Time and Geophysical Fluid Particle DynamicsJan 22 1999Stochastic dynamical systems arise as models for fluid particle motion in geophysical flows with random velocity fields. Escape probability (from a fluid domain) and mean residence time (in a fluid domain) quantify fluid transport between flow regimes ... More
Comparison of simulated longitudinal profiles of hadronic air showers with MASS2 balloon dataMay 16 2002The KASKADE and CORSIKA air shower generators are compared to the data collected by MASS2 balloon experiment in 1991. The test of longitudinal profile for proton, helium and muon flux production provide good constraints on these air shower generators. ... More
On the pion-nucleon coupling constantNov 11 1992In view of persisting misunderstanding about the determination of the pion-nucleon coupling constants in the Nijmegen multienergy partial-wave analyses of pp, np, and pbar-p scattering data, we present additional information which may clarify several ... More
On the "Naturalness" of Buggy CodeJun 03 2015Sep 10 2015Real software, the kind working programmers produce by the kLOC to solve real-world problems, tends to be "natural", like speech or natural language; it tends to be highly repetitive and predictable. Researchers have captured this naturalness of software ... More
F-theory and Neutrinos: Kaluza-Klein Dilution of Flavor HierarchyApr 09 2009Feb 24 2010We study minimal implementations of Majorana and Dirac neutrino scenarios in F-theory GUT models. In both cases the mass scale of the neutrinos m_nu ~ (M_weak)^2/M_UV arises from integrating out Kaluza-Klein modes, where M_UV is close to the GUT scale. ... More
A nonlinear Stokes-Biot model for the interaction of a non-Newtonian fluid with poroelastic mediaMar 02 2018Feb 04 2019We develop and analyze a model for the interaction of a quasi-Newtonian free fluid with a poroelastic medium. The flow in the fluid region is described by the nonlinear Stokes equations and in the poroelastic medium by the nonlinear quasi-static Biot ... More
Neural Lattice DecodersJul 02 2018Feb 04 2019Lattice decoders constructed with neural networks are presented. Firstly, we show how the fundamental parallelotope is used as a compact set for the approximation by a neural lattice decoder. Secondly, we introduce the notion of Voronoi-reduced lattice ... More
On the CVP for the root lattices via folding with deep ReLU neural networksFeb 06 2019Point lattices and their decoding via neural networks are considered in this paper. Lattice decoding in Rn, known as the closest vector problem (CVP), becomes a classification problem in the fundamental parallelotope with a piecewise linear function defining ... More
First-principles methodology for quantum transport in multiterminal junctionsSep 10 2008Sep 24 2009We present a generalized approach for computing electron conductance and I-V characteristics in multiterminal junctions from first-principles. Within the framework of Keldysh theory, electron transmission is evaluated employing an O(N) method for electronic-structure ... More
Electron transport in multi-terminal molecular deviceAug 29 2009The electron transport properties of a four-terminal molecular device are computed within the framework of density functional theory and non-equilibrium Keldysh theory. The additional two terminals lead to new properties, including a pronounced negative ... More
The relative influences of disorder and of frustration on the glassy dynamics in magnetic systemsMar 15 2004The magnetisation relaxations of three different types of geometrically frustrated magnetic systems have been studied with the same experimental procedures as previously used in spin glasses. The materials investigated are Y$_2$Mo$_2$O$_7$ (pyrochlore ... More
Interference Channels with Correlated Receiver Side InformationOct 14 2008The problem of joint source-channel coding in transmitting independent sources over interference channels with correlated receiver side information is studied. When each receiver has side information correlated with its own desired source, it is shown ... More
A Low-Power Content-Addressable-Memory Based on Clustered-Sparse-NetworksFeb 18 2013A low-power Content-Addressable-Memory (CAM) is introduced employing a new mechanism for associativity between the input tags and the corresponding address of the output data. The proposed architecture is based on a recently developed clustered-sparse-network ... More
Aging, rejuvenation and memory effects in re-entrant ferromagnetsMar 06 2002Jul 09 2002We have studied the slow dynamics of the ferromagnetic phases of the re-entrant CdCr_{2x}In_{2-2x}S_4 system for 0.85<x<=1 by means of low frequency ac susceptibility and magnetization measurements. Experimental procedures widely used in the investigation ... More
Multilevel MIMO Detection with Deep LearningDec 04 2018Feb 14 2019A quasi-static flat multiple-antenna channel is considered. We show how real multilevel modulation symbols can be detected via deep neural networks. A multi-plateau sigmoid function is introduced. Then, after showing the DNN architecture for detection, ... More
On the CVP for the root lattices via folding with deep ReLU neural networksFeb 06 2019Feb 28 2019Point lattices and their decoding via neural networks are considered in this paper. Lattice decoding in Rn, known as the closest vector problem (CVP), becomes a classification problem in the fundamental parallelotope with a piecewise linear function defining ... More
The XUV irradiation and likely atmospheric escape of the super-Earth $π$ Men cJan 07 2019$\pi$ Men c was recently announced as the first confirmed exoplanet from the TESS mission. The planet has a radius of just 2 R$_{\rm\oplus}$ and it transits a nearby Sun-like star of naked-eye brightness, making it the ideal target for atmospheric characterisation ... More
Asymptotic Dynamical Difference between the Nonlocal and Local Swift-Hohenberg ModelsJun 18 1998In this paper the difference in the asymptotic dynamics between the nonlocal and local two-dimensional Swift-Hohenberg models is investigated. It is shown that the bounds for the dimensions of the global attractors for the nonlocal and local Swift-Hohenberg ... More
Lossy Source Transmission over the Relay ChannelMay 20 2008Lossy transmission over a relay channel in which the relay has access to correlated side information is considered. First, a joint source-channel decode-and-forward scheme is proposed for general discrete memoryless sources and channels. Then the Gaussian ... More
Joint source and channel coding for MIMO systems: Is it better to be robust or quick?Jan 24 2008We develop a framework to optimize the tradeoff between diversity, multiplexing, and delay in MIMO systems to minimize end-to-end distortion. We first focus on the diversity-multiplexing tradeoff in MIMO systems, and develop analytical results to minimize ... More
Few Graphene layer/Carbon-Nanotube composite Grown at CMOS-compatible TemperatureJan 25 2011We investigate the growth of the recently demonstrated composite material composed of vertically aligned carbon nanotubes capped by few graphene layers. We show that the carbon nanotubes grow epitaxially under the few graphene layers. By using a catalyst ... More
Ruling out the light WIMP explanation of the galactic 511 keV lineFeb 02 2016May 05 2016Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the centre of the Milky Way. Dark matter (DM) in the form of light (< 10 MeV) WIMPs annihilating into electron-positron pairs has been one of the leading hypotheses ... More
Lateral Gene Transfer, Rearrangement and ReconciliationJun 27 2013Background. Models of ancestral gene order reconstruction have progressively integrated different evolutionary patterns and processes such as unequal gene content, gene duplications, and implicitly sequence evolution via reconciled gene trees. In unicellular ... More
Magnetic Field Clumping in Massive Star-Forming Regions as Determined from Excited-State OH Absorption and Maser EmissionJan 10 2005We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2 lines of OH using the GBT in order to investigate whether the magnetic field, and hence the density, measured in absorption differs from that implied by maser Zeeman splitting. ... More
DPG method with optimal test functions for a fractional advection diffusion equationJul 23 2015We develop an ultra-weak variational formulation of a fractional advection diffusion problem in one space dimension and prove its well-posedness. Based on this formulation, we define a DPG approximation with optimal test functions and show its quasi-optimal ... More
A streamlined approach to particle ALD coating of spherical beadsNov 23 2016Nov 24 2016Conformal Atomic Layer Deposition (ALD) of nanoparticles is an now an established nanofabrication concept employed by many researchers for applications such as creating diffusion barriers, tuning catalysis, or masking a toxic particle core with a biocompatible ... More
A lattice-based approach to the expressivity of deep ReLU neural networksFeb 28 2019We present new families of continuous piecewise linear (CPWL) functions in Rn having a number of affine pieces growing exponentially in $n$. We show that these functions can be seen as the high-dimensional generalization of the triangle wave function ... More
Reconstructing compositionsOct 16 2006We consider the problem of reconstructing compositions of an integer from their subcompositions, which was raised by Raykova (albeit disguised as a question about layered permutations). We show that every composition w of n\ge 3k+1 can be reconstructed ... More
Constraints on $Λ(t)$-cosmology with power law interacting dark sectorsMay 30 2012May 31 2012Motivated by the cosmological constant and the coincidence problems, we consider a cosmological model where the cosmological constant $\Lambda_0$ is replaced by a cosmological term $\Lambda(t)$ which is allowed to vary in time. More specifically, we are ... More
The large-scale clustering of massive dark matter haloesMay 06 2010The statistics of peaks of the initial, Gaussian density field can be used to interpret the abundance and clustering of massive dark matter haloes. I discuss some recent theoretical results related to their clustering and its redshift evolution. Predictions ... More
Numerical Simulations of the Ising Model on the Union Jack LatticeJan 26 2011The Ising model is famous model for magnetic substances in Statistical Physics, and has been greatly studied in many forms. It was solved in one-dimension by Ernst Ising in 1925 and in two-dimensions without an external magnetic field by Lars Onsager ... More
Abelianization of Subgroups of Reflection Group and their Braid Group; an Application to CohomologyMar 03 2010Aug 31 2010The final result of this article gives the order of the extension $$\xymatrix{1\ar[r] & P/[P,P] \ar^{j}[r] & B/[P,P] \ar^-{p}[r] & W \ar[r] & 1}$$ as an element of the cohomology group $H^2(W,P/[P,P])$ (where $B$ and $P$ stands for the braid group and ... More
Brick polytopes, lattice quotients, and Hopf algebrasMay 28 2015Nov 30 2017This paper is motivated by the interplay between the Tamari lattice, J.-L. Loday's realization of the associahedron, and J.-L. Loday and M. Ronco's Hopf algebra on binary trees. We show that these constructions extend in the world of acyclic $k$-triangulations, ... More
Shtukas for reductive groups and Langlands correspondence for function fieldsMar 10 2018We discuss recent developments in the Langlands program for function fields, and in the geometric Langlands program. In particular we explain a canonical decomposition of the space of cuspidal automorphic forms for any reductive group G over a function ... More
The metric completion of the Riemannian space of Kähler metricsJan 30 2014Apr 09 2014Let $X$ be a compact K\"ahler manifold and $\a \in H^{1,1}(X,\R)$ a K\"ahler class. We study the metric completion of the space $\HH_\a$ of K\"ahler metrics in $\a$, when endowed with the Mabuchi $L^2$-metric $d$. Using recent ideas of Darvas, we show ... More
Dessins d'enfants for analystsApr 01 2015We present an algorithmic way of exactly computing Belyi functions for hypermaps and triangulations in genus 0 or 1, and the associated dessins, based on a numerical iterative approach initialized from a circle packing combined with subsequent lattice ... More
Conic intersections, Maximal Cohen-Macaulay modules and the Four Subspace problemFeb 21 2017Mar 10 2017Let $X$ be a set of $4$ generic points in $\mathbb{P}^2$ with homogeneous coordinate ring $R$. We classify indecomposable graded MCM modules over $R$ by reducing the classification to the Four Subspace problem solved by Nazarova and Gel$'$fand-Ponomarev, ... More
Many-body renormalisation of forces in f-electron materialsApr 18 2018Aug 30 2018We present the implementation of Dynamical Mean-Field Theory (DMFT) in the CASTEP \emph{ab-initio} code. We explain in detail the theoretical framework for DFT+DMFT and we demonstrate our implementation for three strongly-correlated systems with $f$-shell ... More
Aging, rejuvenation and memory phenomena in spin glassesJun 29 2004Oct 22 2004In this paper, we review several important features of the out-of-equilibrium dynamics of spin glasses. Starting with the simplest experiments, we discuss the scaling laws used to describe the isothermal aging observed in spin glasses after a quench down ... More
A new experimental procedure for characterizing quantum effects in small magnetic particle systemsOct 17 1996Mar 27 1997A new experimental procedure is discussed, which aims at separating thermal from quantum behavior independently of the energy barrier distribution in small particle systems. Magnetization relaxation data measured between 60 mK and 5 K on a sample of nanoparticles ... More
Spin Anisotropy and Slow Dynamics in Spin GlassesMay 05 2003Apr 19 2004We report on an extensive study of the influence of spin anisotropy on spin glass aging dynamics. New temperature cycle experiments allow us to compare quantitatively the memory effect in four Heisenberg spin glasses with various degrees of random anisotropy ... More
Comment on "Unraveling the 'Pressure Effect' in Nucleation"Mar 31 2016In a 2008 Letter, Wedekind et al. discussed the influence of an inert carrier gas on the vapor-liquid nucleation rate. They found an additional "pressure-volume work" that is performed against the carrier gas, and also quantified the nonisothermal effects ... More
The greedy flip tree of a subword complexMar 11 2012Oct 05 2012We describe a canonical spanning tree of the ridge graph of a subword complex on a finite Coxeter group. It is based on properties of greedy facets in subword complexes, defined and studied in this paper. Searching this tree yields an enumeration scheme ... More
Tensor product for symmetric monoidal categoriesNov 02 2007Jun 11 2008We introduce a tensor product for symmetric monoidal categories with the following properties. Let SMC denote the 2-category with objects small symmetric monoidal categories, arrows symmetric monoidal functors and 2-cells monoidal natural transformations. ... More
Introduction aux chtoucas pour les groupes réductifs et à la paramétrisation de Langlands globaleApr 15 2014Dec 24 2017This is an introduction to the article "Chtoucas pour les groupes r\'eductifs et param\'etrisation de Langlands globale", arXiv:1209.5352. We explain all the ideas of the proof. For any reductive group G over a global function field, we use the cohomology ... More
Chtoucas pour les groupes réductifs et paramétrisation de Langlands globaleSep 24 2012Jan 10 2018For any reductive group G over a global function field, we use the cohomology of G-shtukas with multiple modifications and the geometric Satake equivalence to prove the global Langlands correspondence for G in the "automorphic to Galois" direction. Moreover ... More
Behavior of the Euler scheme with decreasing step in a degenerate situationApr 03 2006The aim of this paper is to study the behavior of the weighted empirical measures of the decreasing step Euler scheme of a one-dimensional diffusion process having multiple invariant measures. This situation can occur when the drift and the diffusion ... More
Condensation of polyhedric structures onto soap filmsJun 18 2009Sep 29 2009We study the existence of solutions to general measure-minimization problems over topological classes that are stable under localized Lipschitz homotopy, including the standard Plateau problem without the need for restrictive assumptions such as orientability ... More
Crossing probabilities for Voronoi percolationOct 24 2014Jul 30 2015We prove that the standard Russo-Seymour-Welsh theory is valid for Voronoi percolation. This implies that at criticality the crossing probabilities for rectangles are bounded by constants depending only on their aspect ratio. This result has many consequences, ... More
Flatness, accessibility and metric spacesMar 09 2004This paper studies a notion of parameterized flatness in the enriched context: p-flatness where the parameter p stands for a class of presheaves. One obtains a completion of a category A by considering the category F_p(A) of p-flat presheaves over A. ... More
Chtoucas pour les groupes réductifs et paramétrisation de Langlands globaleSep 24 2012Sep 28 2016For any reductive group G over a global function field, we use the cohomology of G-shtukas with multiple modifications and the geometric Satake equivalence to prove the global Langlands correspondence for G in the direction "from automorphic to Galois". ... More
Infinite determinacy on a closed set for smooth germs with non-isolated singularitiesJun 13 2004Oct 18 2004We give necessary and sufficient conditions of infinite determinacy for smooth function germs whose critical locus contains a given set. This set is assumed to be the zero variety X of some analytic map germ having maximal rank on a dense subset of X. ... More
Radio emission and nonlinear diffusive shock acceleration of cosmic rays in the supernova SN 1993JMar 17 2009The extensive observations of the supernova SN 1993J at radio wavelengths make this object a unique target for the study of particle acceleration in a supernova shock. To describe the radio synchrotron emission we use a model that couples a semianalytic ... More
Surviving particles for subcritical branching processes in random environmentApr 05 2008Dec 10 2008The asymptotic behavior of a subcritical Branching Process in Random Environment (BPRE) starting with several particles depends on whether the BPRE is strongly subcritical (SS), intermediate subcritical (IS) or weakly subcritical (WS). %Descendances of ... More
Divergent directions in some periodic wind-tree modelsJul 12 2011Jul 14 2011The periodic wind-tree model is a family T(a,b) of billiards in the plane in which identical rectangular scatterers of size axb are disposed at each integer point. It was proven by P. Hubert, S. Leli\`evre and S. Troubetzkoy (arXiv:0912.2891v1) that for ... More
Actions of finitely generated groups on R-treesJul 12 2006Apr 25 2007We study actions of finitely generated groups on $\bbR$-trees under some stability hypotheses. We prove that either the group splits over some controlled subgroup (fixing an arc in particular), or the action can be obtained by gluing together actions ... More
Asymptotics of lieanders with fixed composition sizesDec 10 2018Lieanders are special cases of meanders and first appeared in connection with Lie algebras. Using the results from the author with E. Goujard, P. Zograf and A. Zorich, we prove a polynomial asymptotics for the number of lieanders with fixed composition ... More
On VC-density in VC-minimal theoriesSep 29 2014We show that any formula with two free variables in a VC-minimal theory has VC-codensity at most two. Modifying the argument slightly, we give a new proof of the fact that, in a VC-minimal theory where acl = dcl, the VC-codensity of a formula is at most ... More
Dependence and Isolated ExtensionsNov 06 2009In this paper, we show that \phi is a dependent formula if and only if all \phi-types have an extension to a \phi-isolated \phi-type that is an "elementary \phi-extension" (see Definition 2.3 in the paper). Moreover, we show that the domain of this extension ... More
Convergence at the origin of integrated semigroupsApr 22 2004Aug 04 2008We study a classification of the kappa-times integrated semigroups (for kappa>0) by the (uniform) rate of convergence at the origin: $\|S(t)\|=O(t^\alpha)$, $0\leq\alpha\leq\kappa$. By an improved generation theorem we characterize this behaviour by Hille-Yosida ... More
Division by Flat Ultradifferentiable Functions and Sectorial ExtensionsFeb 17 2006We consider classes $ \mathcal{A}_M(S) $ of functions holomorphic in an open plane sector $ S $ and belonging to a strongly non-quasianalytic class on the closure of $ S $. In $ \mathcal{A}_M(S) $, we construct functions which are flat at the vertex of ... More
On the Stability of Analytic Germs under Ultradifferentiable PerturbationsJan 05 2006Let $ f$ be a real-analytic function germ whose critical locus contains a given real-analytic set $ X $, and let $ Y $ be a germ of closed subset of $ \mathbb{R}^n $ at the origin. We study the stability of $ f $ under perturbations $ u $ that are flat ... More
Łojasiewicz ideals in Denjoy-Carleman classesOct 23 2012Jul 22 2013The classical notion of {\L}ojasiewicz ideals of smooth functions is studied in the context of non-quasianalytic Denjoy-Carleman classes. In the case of principal ideals, we obtain a characterization of {\L}ojasiewicz ideals in terms of properties of ... More
Introduction to chtoucas for reductive groups and to the global Langlands parameterizationApr 25 2014Dec 24 2017This is a translation in English of version 5 of the article arXiv:1404.3998, which is itself an introduction to arXiv:1209.5352. We explain all the ideas of the proof of the following theorem. For any reductive group G over a global function field, we ... More
On the Limit Imbalanced Logistic Regression by Binary PredictorsMar 27 2017Apr 18 2018In this work, we introduce a modified (rescaled) likelihood for imbalanced logistic regression. This new approach makes easier the use of exponential priors and the computation of lasso regularization path. Precisely, we study a limiting behavior for ... More
Betti tables for indecomposable matrix factorizations of $XY(X-Y)(X-λY)$Dec 19 2017We classify the Betti tables of indecomposable graded matrix factorizations over the simple elliptic singularity $f_\lambda = XY(X-Y)(X-\lambda Y)$ by making use of an associated weighted projective line of genus one.
Les applications conforme-harmoniquesMar 25 2012On a Riemannian surface, the energy of a map into a Riemannian manifold is a conformal invariant functional, and its critical points are the harmonic maps. Our main result is a generalization of this theorem when the starting manifold is even dimensional. ... More
Inverse conductivity problem in dimension twoMar 10 2017May 07 2017This article proposes a process to reconstruct a Riemann surface with boundary equipped with a conductivity tensor from its boundary and its Dirichlet-Neumann operator. When initial data comes from a two dimensional real Riemannian oriented surface equipped ... More
Lorentzian manifolds with a conformal action of SL(2,R)Sep 01 2016Sep 19 2016We consider conformal actions of simple Lie groups on compact Lorentzian manifolds. Mainly motivated by the Lorentzian version of a conjecture of Lichnerowicz, we establish the alternative: Either the group acts isometrically for some metric in the conformal ... More
Hopf algebras on decorated noncrossing arc diagramsJan 11 2018Aug 06 2018Noncrossing arc diagrams are combinatorial models for the equivalence classes of the lattice congruences of the weak order on permutations. In this paper, we provide a general method to endow these objects with Hopf algebra structures. Specific instances ... More
Small permutation classesDec 24 2007Apr 05 2016We establish a phase transition for permutation classes (downsets of permutations under the permutation containment order): there is an algebraic number $\kappa$, approximately 2.20557, for which there are only countably many permutation classes of growth ... More
Maximal independent sets and separating coversNov 21 2009Aug 26 2010In 1973, Katona raised the problem of determining the maximum number of subsets in a separating cover on n elements. The answer to Katona's question turns out to be the inverse to the answer to a much simpler question: what is the largest integer which ... More
Eliciting Single-Peaked Preferences Using Comparison QueriesJan 15 2014Voting is a general method for aggregating the preferences of multiple agents. Each agent ranks all the possible alternatives, and based on this, an aggregate ranking of the alternatives (or at least a winning alternative) is produced. However, when there ... More
Prediction Markets, Mechanism Design, and Cooperative Game TheoryMay 09 2012Prediction markets are designed to elicit information from multiple agents in order to predict (obtain probabilities for) future events. A good prediction market incentivizes agents to reveal their information truthfully; such incentive compatibility ... More
Cohomologie de de Rham entiere (Integral de Rham cohomology)Apr 06 2004Apr 06 2004The Cartier isomorphism allows a nice description of the Bockstein spectral sequence of the de Rham complex over the integers. It is used to compute the integral de Rham cohomology of affine spaces. ----- On decrit la suite spectrale de Bockstein issue ... More
X- and Gamma-Ray Line Emission ProcessesAug 21 2002This chapter is intended to provide a general presentation of the atomic and nuclear processes responsible for X-ray line and gamma-ray line emission in various astrophysical environments. I consider line production from hot plasmas, from accelerated ... More
Can the coincidence problem be solved by a cosmological model of coupled dark energy and dark matter?Jul 23 2013Oct 12 2014Motivated by the cosmological constant and the coincidence problems, we consider a cosmological model where the dark sectors are interacting together through a phenomenological decay law $\dot{\rho}_{\Lambda}=Q\rho_{\Lambda}^n$ in a FRW spacetime with ... More
Baryon acoustic signature in the clustering of density maximaJun 02 2008Oct 22 2008We reexamine the two-point correlation of density maxima in Gaussian initial conditions. Spatial derivatives of the linear density correlation, which were ignored in the calculation of Bardeen, Bond, Kaiser & Szalay (1986), are included in our analysis. ... More
Environmental dependence in the ellipsoidal collapse modelJul 31 2007May 15 2008N-body simulations have demonstrated a correlation between the properties of haloes and their environment. In this paper, we assess whether the ellipsoidal collapse model can produce a similar dependence. First, we explore the statistical correlation ... More
Proof of the Tadic conjecture U0 on the unitary dual of GL(m,D)Feb 01 2007Let F be a non-Archimedean local field of characteristic 0, and let D be a finite dimensional central division algebra over F. We prove that any unitary irreducible representation of a Levi subgroup of GL(m,D), with m a positive integer, induces irreducibly ... More
Group analysis of an ideal plasticity modelJan 05 2012In this paper, we study the Lie point symmetry group of a system describing an ideal plastic plane flow in two dimensions in order to find analytical solutions of the system. The infinitesimal generators that span the Lie algebra for this system are obtained, ... More
Remplissage De L'Espace Euclidien Par Des Complexes PolyÉdriques D'Orientation ImposÉe Et De RotonditÉ UniformeDec 26 2008We build polyhedral complexes in Rn that coincide with dyadic grids with different orientations, while keeping uniform lower bounds (depending only on n) on the flatness of the added polyhedrons including their subfaces in all dimensions. After the definitions ... More
Diffusion of a particle quadratically coupled to a thermally fluctuating fieldFeb 09 2013Apr 19 2013We study the diffusion of a Brownian particle quadratically coupled to a thermally fluctuating field. In the weak coupling limit, a path-integral formulation allows to compute the effective diffusion coefficient in the cases of an active particle, that ... More
On the trace and norm maps from $Γ_0(\mathfrak{p})$ to $\operatorname{GL}_2(A)$Jun 16 2014Let $f$ be a Drinfeld modular form for $\Gamma_0(\mathfrak{p})$. From such a form, one can obtain two forms for the full modular group $\operatorname{GL}_2(A)$: by taking the trace or the norm from $\Gamma_0(\mathfrak{p})$ to $\operatorname{GL}_2(A)$. ... More
An Erdős--Hajnal analogue for permutation classesNov 03 2015Feb 09 2016Let $\mathcal{C}$ be a permutation class that does not contain all layered permutations or all colayered permutations. We prove that there is a constant $c$ such that every permutation in $\mathcal{C}$ of length $n$ contains a monotone subsequence of ... More
Comptage de représentations cuspidales congruentesJul 09 2015Let $F$ be a non-Archimedean locally compact field of residue characteristic $p$, $G$ be an inner form of $GL_n(F)$, $n\ge1$, and $\ell$ be a prime number different from $p$. We give a numerical criterion for an integral $\ell$-adic irreducible cuspidal ... More
The multilayer shallow water system in the limit of small density contrastJul 08 2015Jan 19 2016We study the inviscid multilayer Saint-Venant (or shallow-water) system in the limit of small density contrast. We show that, under reasonable hyperbolicity conditions on the flow and a smallness assumption on the initial surface deformation, the system ... More