1,530 results
Search Results
2. AN ALMOST SCHUR THEOREM ON 4-DIMENSIONAL MANIFOLDS
- Author
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Guofang Wang, Yuxin Ge, Laboratoire d'Analyse et de Mathématiques Appliquées (LAMA), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Fédération de Recherche Bézout-Université Paris-Est Marne-la-Vallée (UPEM), and Université Paris-Est Marne-la-Vallée (UPEM)-Fédération de Recherche Bézout-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)
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Pure mathematics ,010308 nuclear & particles physics ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Mathematical analysis ,Short paper ,01 natural sciences ,Schur's theorem ,Computer Science::Computers and Society ,[MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph] ,Ricci-flat manifold ,0103 physical sciences ,Sectional curvature ,Mathematics::Differential Geometry ,0101 mathematics ,Mathematics::Symplectic Geometry ,Schur product theorem ,Mathematics ,Scalar curvature - Abstract
International audience; In this short paper we prove that the almost Schur theorem, introduced by De Lellis and Topping, is true on 4-dimensional Riemannian manifolds of nonnegative scalar curvature and discuss some related problems on other dimensional manifolds.
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- 2012
3. Robust simulation of rational discrete-time systems via sum of squares relaxations
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Paolo Massioni, Gérard Scorletti, Ampère, Département Méthodes pour l'Ingénierie des Systèmes (MIS), Ampère (AMPERE), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-École Centrale de Lyon (ECL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
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0209 industrial biotechnology ,Class (set theory) ,Mathematical optimization ,010102 general mathematics ,Explained sum of squares ,02 engineering and technology ,State (functional analysis) ,16. Peace & justice ,robust simulation ,01 natural sciences ,Ellipsoid ,[SPI.AUTO]Engineering Sciences [physics]/Automatic ,Set (abstract data type) ,Nonlinear system ,020901 industrial engineering & automation ,Fractal ,Discrete time and continuous time ,Control and Systems Engineering ,fractals ,Discrete-time systems ,Applied mathematics ,0101 mathematics ,sum of squares ,linear matrix inequalities ,Mathematics - Abstract
International audience; This paper concerns the simulation of a class of nonlinear discrete-time systems under a set of initial conditions described by an ellipsoid. We derive a procedure allowing the propagation of such ellipsoids through time, which makes it possible to set a guaranteed hard bound on the evolution of the state of the system for all the possible initial conditions. At the end of the paper, we show an application of the method through three academics examples, two of which are taken from the theory of fractals.
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- 2017
4. On the asymptotic normality of the R-estimators of the slope parameters of simple linear regression models with associated errors
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Dalibor Volný, Ryozo Miura, Sana Louhichi, Inférence Processus Stochastiques (IPS), Laboratoire Jean Kuntzmann (LJK ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Hitotsubashi University, Laboratoire de Mathématiques Raphaël Salem (LMRS), Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)
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Statistics and Probability ,rank statistics ,Rank (linear algebra) ,asymptotic normality ,Asymptotic distribution ,01 natural sciences ,Combinatorics ,010104 statistics & probability ,[MATH.MATH-ST]Mathematics [math]/Statistics [math.ST] ,Applied mathematics ,mixing ,Robust estimators ,0101 mathematics ,Empirical process ,Mathematics ,Weak convergence ,010102 general mathematics ,Linear model ,association ,Estimator ,Regression analysis ,r-estimators ,16. Peace & justice ,weighted empirical processes ,dependent errors ,Statistics, Probability and Uncertainty ,Simple linear regression ,linear models - Abstract
International audience; The purpose of this paper is to prove, under mild conditions, the asymptotic normality of the rank estimator of the slope parameter of a simple linear regression model with stationary associated errors. This result follows from a uniform linearity property for linear rank statistics that we establish under general conditions on the dependence of the errors. We prove also a tightness criterion for weighted empirical process constructed from associated triangular arrays. This criterion is needed for the proofs which are based on that of Koul [Behavior of robust estimators in the regression model with dependent errors. Ann Stat. 1977;5(4):681–699] and of Louhichi [Louhichi S. Weak convergence for empirical processes of associated sequences. Ann Inst Henri Poincaré Probabilités Statist. 2000;36(5):547–567].
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- 2017
5. A cramér type moderate deviation theorem for the critical curie-weiss model
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Van Hao Can, Viet-Hung Pham, Institut de Mathématiques de Marseille (I2M), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Institut de Mathématiques de Toulouse UMR5219 (IMT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)
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Statistics and Probability ,82B20 ,Moderate deviation ,Type (model theory) ,01 natural sciences ,010104 statistics & probability ,Magnetization ,Simple (abstract algebra) ,[MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph] ,Calculus ,Applied mathematics ,0101 mathematics ,Mathematical Physics ,Mathematics ,Curie–Weiss law ,Curie-Weiss model ,010102 general mathematics ,16. Peace & justice ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Laplace's method ,Moderate deviations ,Statistics, Probability and Uncertainty ,Cramér type moderate deviation ,60F10, 82B20 ,Mathematics - Probability ,60F10 - Abstract
In this paper we study the moderate deviations for the magnetization of critical Curie-Weiss model. Chen, Fang and Shao considered a similar problem for non-critical model by using Stein method. By direct and simple arguments based on Laplace method, we provide an explicit formula of the error and deduce a Cram\'er-type result., Comment: 12 pages, accepted for publication in Electronic Communication in Probability
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- 2017
6. Single point blow-up and final profile for a perturbed nonlinear heat equation with a gradient and a non-local term
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Bouthaina Abdelhedi, Hatem Zaag, Laboratoire Analyse, Géométrie et Applications (LAGA), and Université Paris 8 Vincennes-Saint-Denis (UP8)-Centre National de la Recherche Scientifique (CNRS)-Institut Galilée-Université Paris 13 (UP13)
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Work (thermodynamics) ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,Perturbation (astronomy) ,Derivative ,Space (mathematics) ,01 natural sciences ,Term (time) ,010101 applied mathematics ,Nonlinear heat equation ,Mathematics - Analysis of PDEs ,Mathematics::Algebraic Geometry ,FOS: Mathematics ,Discrete Mathematics and Combinatorics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,Heat equation ,0101 mathematics ,Single point ,35K55, 35B20, 35B44 ,Analysis ,ComputingMilieux_MISCELLANEOUS ,Mathematics ,Analysis of PDEs (math.AP) - Abstract
We consider in this paper a perturbation of the standard semilinear heat equation by a term involving the space derivative and a non-local term. In some earlier work (Abdelhedi-Zaag JDE 2021), we constructed a blow-up solution for that equation, and showed that it blows up (at least) at the origin. We also derived the so called "intermediate blow-up profile". In this paper, we prove the single point blow-up property and determine the final blow-up profile.
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- 2021
7. Analysis of the heart-torso conductivity parameters recovery inverse problem in cardiac electrophysiology ECG modelling
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Mourad Bellassoued, Nejib Zemzemi, Moncef Mahjoub, Abir Amri, Ecole Nationale d'Ingénieurs de Tunis (ENIT), Université de Tunis El Manar (UTM), Modélisation et calculs pour l'électrophysiologie cardiaque (CARMEN), IHU-LIRYC, Université Bordeaux Segalen - Bordeaux 2-CHU Bordeaux [Bordeaux]-Université Bordeaux Segalen - Bordeaux 2-CHU Bordeaux [Bordeaux]-Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), This work has been supported by EPICARD cooperative research program, funded by INRIA international laboratory LIRIMA. The LAMSIN researcher’s work is supported on a regular basis by the Tunisian Ministry ofHigher Education, Scientific Research and Technology. This work was also supported by the Agence Nationale de la Recherche (grant number IHU LIRYC ANR-10-IAHU-04)., Epicard, Lirima, SPICY, ANR-10-IAHU-0004,LIRYC,L'Institut de Rythmologie et modélisation Cardiaque(2010), Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IHU-LIRYC, and Université Bordeaux Segalen - Bordeaux 2-CHU Bordeaux [Bordeaux]-CHU Bordeaux [Bordeaux]
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Quantitative Biology::Tissues and Organs ,Physics::Medical Physics ,Conductivity parameters ,Cardiac electrophysiology ,Carleman estimate ,01 natural sciences ,Stability (probability) ,Computer Science::Robotics ,2010 Mathematics Subject Classification.Primary 35Q92, Secondary: 35R30 ,medicine ,0101 mathematics ,Stability estimate ,Monodomain model ,Mathematics ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Inverse problem ,Torso ,Lipschitz continuity ,[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation ,010101 applied mathematics ,Parameter identification problem ,Elliptic curve ,medicine.anatomical_structure ,Analysis - Abstract
International audience; In this paper, we prove a stability estimate of the conductivity parameters identification problem in cardiac electrophysiology. The propagation of the electrical wave in the heart is described by the monodomain model coupled to an elliptic equation describing the diffusion of the electrical wave in the whole body. Our result concerns both heart and torso conductivity parameters. The main difficulty that we solve in this paper is related to the transmission conditions between the heart and the torso. We first, establish Carleman estimates for the coupled heart-torso system. Then, using these estimates and the Bukhgeim and Klibanov approach, we prove a Lipschitz stability estimate of cardiac and torso conductivity parameters.
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- 2021
8. On change-points tests based on two-samples U-Statistics for weakly dependent observations
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Joseph Ngatchou-Wandji, Michel Harel, Echarif Elharfaoui, Institut Élie Cartan de Lorraine (IECL), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), École des Hautes Études en Santé Publique [EHESP] (EHESP), Université Chouaib Doukkali (UCD), Institut de Mathématiques de Toulouse UMR5219 (IMT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut national supérieur du professorat et de l'éducation Toulouse Occitanie-Pyrénées (INSPE Toulouse), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)
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Statistics and Probability ,Sequence ,[STAT.AP]Statistics [stat]/Applications [stat.AP] ,Series (mathematics) ,010102 general mathematics ,Autocorrelation ,Variance (accounting) ,[STAT.TH]Statistics [stat]/Statistics Theory [stat.TH] ,01 natural sciences ,Small set ,010104 statistics & probability ,[MATH.MATH-ST]Mathematics [math]/Statistics [math.ST] ,Kernel (statistics) ,Applied mathematics ,0101 mathematics ,Statistics, Probability and Uncertainty ,Null hypothesis ,[STAT.ME]Statistics [stat]/Methodology [stat.ME] ,Statistical hypothesis testing ,Mathematics - Abstract
International audience; We study change-points tests based on U-statistics for absolutely regular observations. Our method avoids some technical assumptions on the data and the kernel. The asymptotic properties of the U-statistics are studied under the null hypothesis, under fixed alternatives and under a sequence of local alternatives. The asymptotic distributions of the test statistics under the null hypothesis and under the local alternatives are given explicitly and the tests are shown to be consistent. A small set of simulations is done for evaluating the performance of the tests in detecting changes in the mean, variance and autocorrelation of some simple time series.
- Published
- 2021
9. Eigenvalues of the truncated Helmholtz solution operator under strong trapping
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Euan A. Spence, Pierre Marchand, Jeffrey Galkowski, University College of London [London] (UCL), and University of Bath [Bath]
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Helmholtz equation ,Existential quantification ,010103 numerical & computational mathematics ,Trapping ,01 natural sciences ,Dirichlet distribution ,Computer Science::Robotics ,symbols.namesake ,Mathematics - Analysis of PDEs ,FOS: Mathematics ,Mathematics - Numerical Analysis ,0101 mathematics ,35J05, 35P15, 35B34, 35P25 ,Eigenvalues and eigenvectors ,Mathematics ,Applied Mathematics ,Operator (physics) ,010102 general mathematics ,Mathematical analysis ,Numerical Analysis (math.NA) ,Mathematics::Spectral Theory ,Computational Mathematics ,Helmholtz free energy ,Obstacle ,symbols ,Analysis ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] ,Analysis of PDEs (math.AP) - Abstract
For the Helmholtz equation posed in the exterior of a Dirichlet obstacle, we prove that if there exists a family of quasimodes (as is the case when the exterior of the obstacle has stable trapped rays), then there exist near-zero eigenvalues of the standard variational formulation of the exterior Dirichlet problem (recall that this formulation involves truncating the exterior domain and applying the exterior Dirichlet-to-Neumann map on the truncation boundary). Our motivation for proving this result is that a) the finite-element method for computing approximations to solutions of the Helmholtz equation is based on the standard variational formulation, and b) the location of eigenvalues, and especially near-zero ones, plays a key role in understanding how iterative solvers such as the generalised minimum residual method (GMRES) behave when used to solve linear systems, in particular those arising from the finite-element method. The result proved in this paper is thus the first step towards rigorously understanding how GMRES behaves when applied to discretisations of high-frequency Helmholtz problems under strong trapping (the subject of the companion paper [Marchand, Galkowski, Spence, Spence, 2021]).
- Published
- 2021
10. Coupling of complex function theory and finite element method for crack propagation through energetic formulation: conformal mapping approach and reduction to a Riemann-Hilbert problem
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Dmitrii Legatiuk, Daniel Weisz-Patrault, Bauhaus-Universität Weimar, Laboratoire de mécanique des solides (LMS), École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
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FOS: Computer and information sciences ,30B40, 30C20, 30E10, 35Q15, 35Q74, 74H10, 74R10 ,Conformal map ,02 engineering and technology ,01 natural sciences ,Computational Engineering, Finance, and Science (cs.CE) ,symbols.namesake ,Singularity ,0203 mechanical engineering ,[PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph] ,FOS: Mathematics ,Riemann–Hilbert problem ,Mathematics - Numerical Analysis ,Boundary value problem ,Complex Variables (math.CV) ,0101 mathematics ,Computer Science - Computational Engineering, Finance, and Science ,Mathematics ,Strain energy release rate ,Mathematics - Complex Variables ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Fracture mechanics ,Numerical Analysis (math.NA) ,Potential energy ,Finite element method ,020303 mechanical engineering & transports ,Computational Theory and Mathematics ,symbols ,Analysis ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] - Abstract
In this paper we present a theoretical background for a coupled analytical–numerical approach to model a crack propagation process in two-dimensional bounded domains. The goal of the coupled analytical–numerical approach is to obtain the correct solution behaviour near the crack tip by help of the analytical solution constructed by using tools of complex function theory and couple it continuously with the finite element solution in the region far from the singularity. In this way, crack propagation could be modelled without using remeshing. Possible directions of crack growth can be calculated through the minimization of the total energy composed of the potential energy and the dissipated energy based on the energy release rate. Within this setting, an analytical solution of a mixed boundary value problem based on complex analysis and conformal mapping techniques is presented in a circular region containing an arbitrary crack path. More precisely, the linear elastic problem is transformed into a Riemann–Hilbert problem in the unit disk for holomorphic functions. Utilising advantages of the analytical solution in the region near the crack tip, the total energy could be evaluated within short computation times for various crack kink angles and lengths leading to a potentially efficient way of computing the minimization procedure. To this end, the paper presents a general strategy of the new coupled approach for crack propagation modelling. Additionally, we also discuss obstacles in the way of practical realisation of this strategy.
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- 2021
11. Weak solutions for potential mean field games of controls
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Alan Mullenix, P. Jameson Graber, Laurent Pfeiffer, Department of Mathematics, Baylor University, Controle, Optimisation, modèles, Méthodes et Applications pour les Systèmes Dynamiques non linéaires (COMMANDS), Centre de Mathématiques Appliquées - Ecole Polytechnique (CMAP), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, and Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)
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Computer Science::Computer Science and Game Theory ,0209 industrial biotechnology ,02 engineering and technology ,01 natural sciences ,mean field games of controls ,symbols.namesake ,optimal control ,020901 industrial engineering & automation ,Mathematics - Analysis of PDEs ,Bellman equation ,weak solutions ,FOS: Mathematics ,Applied mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,0101 mathematics ,[MATH]Mathematics [math] ,Mathematics ,Partial differential equation ,Applied Mathematics ,Weak solution ,010102 general mathematics ,Degenerate energy levels ,mean field games ,calculus of variations ,State (functional analysis) ,Function (mathematics) ,Action (physics) ,Nash equilibrium ,symbols ,Analysis ,Analysis of PDEs (math.AP) - Abstract
International audience; We analyze a system of partial differential equations that model a potential mean field game of controls, briefly MFGC. Such a game describes the interaction of infinitely many negligible players competing to optimize a personal value function that depends in aggregate on the state and, most notably, control choice of all other players. A solution of the system corresponds to a Nash Equilibrium, a group optimal strategy for which no one player can improve by altering only their own action. We investigate the second order, possibly degenerate, case with non-strictly elliptic diffusion operator and local coupling function. The main result exploits potentiality to employ variational techniques to provide a unique weak solution to the system, with additional space and time regularity results under additional assumptions. New analytical subtleties occur in obtaining a priori estimates with the introduction of an additional coupling that depends on the state distribution as well as feedback.
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- 2021
12. Mixed hyperbolic/trigonometric non-stationary subdivision scheme
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Ahmed Zidna, A. Lamnii, R. Fakhar, M. Y. Nour, Université Hassan 1er [Settat], Laboratoire de Génie Informatique, de Production et de Maintenance (LGIPM), and Université de Lorraine (UL)
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Smoothness ,business.industry ,010102 general mathematics ,MathematicsofComputing_NUMERICALANALYSIS ,Context (language use) ,01 natural sciences ,Shape parameter ,010101 applied mathematics ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,Convergence (routing) ,Applied mathematics ,Polygon mesh ,[INFO]Computer Science [cs] ,0101 mathematics ,Trigonometry ,business ,Equivalence (measure theory) ,ComputingMilieux_MISCELLANEOUS ,ComputingMethodologies_COMPUTERGRAPHICS ,Subdivision ,Mathematics - Abstract
This paper proposes two novel families of non-stationary subdivision schemes with a shape parameter of hierarchically and efficiently generating mixed hyperbolic/trigonometric curves of order 3 and 4. An analysis of convergence and smoothness of the proposed schemes is established by using the asymptotic equivalence method. This paper also discusses the bivariate tensor-product subdivision scheme for the surface modeling on the regular meshes. The numerical results they produce are very encouraging. In this context, the performance of our algorithms has been exposed by considering examples, which illustrate how the shape parameter and the control points are assigned to reproduce such analytic curves and surfaces using tensor-product notion.
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- 2021
13. On polynomially integrable Birkhoff billiards on surfaces of constant curvature
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Alexey Glutsyuk, UMPA, Unité de Mathématiques Pures et Appliquées (UMPA-ENSL), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS), ANR-13-JS01-0010,VALET,Renormalisation et théorèmes limites en théorie ergodique (VALET=Vershik's automorphisms, limits in ergodic theory)(2013), and École normale supérieure de Lyon (ENS de Lyon)-Centre National de la Recherche Scientifique (CNRS)
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Surface (mathematics) ,Pure mathematics ,37J30, 37E40, 14H50 ,Plane (geometry) ,Applied Mathematics ,General Mathematics ,Hyperbolic geometry ,010102 general mathematics ,[MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS] ,Boundary (topology) ,Dynamical Systems (math.DS) ,01 natural sciences ,Constant curvature ,Conic section ,FOS: Mathematics ,Algebraic curve ,0101 mathematics ,Dynamical billiards ,Mathematics - Dynamical Systems ,Mathematics - Abstract
We present a solution of the algebraic version of Birkhoff Conjecture on integrable billiards. Namely we show that every polynomially integrable real bounded convex planar billiard with smooth boundary is an ellipse. We extend this result to billiards with piecewise-smooth and not necessarily convex boundary on arbitrary two-dimensional surface of constant curvature: plane, sphere, Lobachevsky (hyperbolic) plane; each of them being modeled as a plane or a (pseudo-) sphere in $\mathbb R^3$ equipped with appropriate quadratic form. Namely, we show that a billiard is polynomially integrable, if and only if its boundary is a union of confocal conical arcs and appropriate geodesic segments. We also present a complexification of these results. These are joint results of Mikhail Bialy, Andrey Mironov and the author. The proof is split into two parts. The first part is given by Bialy and Mironov in their two joint papers. They considered the tautological projection of the boundary to $\mathbb{RP}^2$ and studied its orthogonal-polar dual curve, which is piecewise algebraic, by S.V.Bolotin's theorem. By their arguments and another Bolotin's theorem, it suffices to show that each non-linear complex irreducible component of the dual curve is a conic. They have proved that all its singularities and inflection points (if any) lie in the projectivized zero locus of the corresponding quadratic form on $\mathbb C^3$. The present paper provides the second part of the proof: we show that each above irreducible component is a conic and finish the solution of the Algebraic Birkhoff Conjecture in constant curvature., To appear in the Journal of the European Mathematical Society (JEMS), 69 pages, 2 figures. A shorter proof of Theorem 4.24. Minor precisions and misprint corrections
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- 2021
14. On bayesian estimation and proximity operators
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Rémi Gribonval, Mila Nikolova, Parcimonie et Nouveaux Algorithmes pour le Signal et la Modélisation Audio (PANAMA), SIGNAUX ET IMAGES NUMÉRIQUES, ROBOTIQUE (IRISA-D5), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes 1 (UR1), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria), Centre de Mathématiques et de Leurs Applications (CMLA), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-SIGNAUX ET IMAGES NUMÉRIQUES, ROBOTIQUE (IRISA-D5), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Université de Bretagne Sud (UBS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-CentraleSupélec-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Bretagne Sud (UBS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1)
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Bayes estimator ,Minimum mean square error ,Applied Mathematics ,Noise reduction ,Gaussian ,010102 general mathematics ,Mathematics - Statistics Theory ,010103 numerical & computational mathematics ,[STAT.TH]Statistics [stat]/Statistics Theory [stat.TH] ,01 natural sciences ,symbols.namesake ,Exponential family ,[INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing ,Gaussian noise ,Prior probability ,symbols ,Maximum a posteriori estimation ,Applied mathematics ,0101 mathematics ,Mathematics - Abstract
There are two major routes to address the ubiquitous family of inverse problems appearing in signal and image processing, such as denoising or deblurring. A first route relies on Bayesian modeling, where prior probabilities are used to embody models of both the distribution of the unknown variables and their statistical dependence with the observed data. The estimation process typically relies on the minimization of an expected loss (e.g. minimum mean squared error, or MMSE). The second route has received much attention in the context of sparse regularization and compressive sensing: it consists in designing (often convex) optimization problems involving the sum of a data fidelity term and a penalty term promoting certain types of unknowns (e.g., sparsity, promoted through an 1 norm). Well known relations between these two approaches have lead to some widely spread misconceptions. In particular, while the so-called Maximum A Posterori (MAP) estimate with a Gaussian noise model does lead to an optimization problem with a quadratic data-fidelity term, we disprove through explicit examples the common belief that the converse would be true. It has already been shown [7, 9] that for denoising in the presence of additive Gaussian noise, for any prior probability on the unknowns, MMSE estimation can be expressed as a penalized least squares problem, with the apparent characteristics of a MAP estimation problem with Gaussian noise and a (generally) different prior on the unknowns. In other words, the variational approach is rich enough to build all possible MMSE estimators associated to additive Gaussian noise via a well chosen penalty. We generalize these results beyond Gaussian denoising and characterize noise models for which the same phenomenon occurs. In particular, we prove that with (a variant of) Poisson noise and any prior probability on the unknowns, MMSE estimation can again be expressed as the solution of a penalized least squares optimization problem. For additive scalar denois-ing the phenomenon holds if and only if the noise distribution is log-concave. In particular, Laplacian denoising can (perhaps surprisingly) be expressed as the solution of a penalized least squares problem. In the multivariate case, the same phenomenon occurs when the noise model belongs to a particular subset of the exponential family. For multivariate additive denoising, the phenomenon holds if and only if the noise is white and Gaussian., Comment: This work and the companion paper [10] are dedicated to the memory of Mila Nikolova, who passed away prematurely in June 2018. Mila dedicated much of her energy to bring the technical content to completion during the spring of 2018. The first author did his best to finalize the papers as Mila would have wished. He should be held responsible for any possible imperfection in the final manuscript
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- 2021
15. New results on approximate Hilbert pairs of wavelet filters with common factors
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Sophie Achard, Irène Gannaz, François Roueff, Marianne Clausel, GIPSA - Vision and Brain Signal Processing (GIPSA-VIBS), GIPSA Pôle Sciences des Données (GIPSA-PSD), Grenoble Images Parole Signal Automatique (GIPSA-lab), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Grenoble Images Parole Signal Automatique (GIPSA-lab), Université Grenoble Alpes (UGA), Institut Élie Cartan de Lorraine (IECL), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Probabilités, statistique, physique mathématique (PSPM), Institut Camille Jordan [Villeurbanne] (ICJ), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Traitement et Communication de l'Information (LTCI), and Télécom ParisTech-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)
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FOS: Computer and information sciences ,[STAT.AP]Statistics [stat]/Applications [stat.AP] ,Hilbert-pair ,Finite impulse response ,orthonormal filter banks ,Applied Mathematics ,Imaginary part ,010102 general mathematics ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,010103 numerical & computational mathematics ,Vanishing moments ,Construct (python library) ,Statistics - Applications ,01 natural sciences ,Perfect reconstruction ,common-factor wavelets ,Methodology (stat.ME) ,Wavelet ,Applied mathematics ,Applications (stat.AP) ,0101 mathematics ,Complex wavelet ,[STAT.ME]Statistics [stat]/Methodology [stat.ME] ,Statistics - Methodology ,Mathematics - Abstract
International audience; In this paper, we consider the design of wavelet filters based on the Thiran common-factor approach proposed in Selesnick [2001]. This approach aims at building finite impulse response filters of a Hilbert-pair of wavelets serving as real and imaginary part of a complex wavelet. Unfortunately it is not possible to construct wavelets which are both finitely supported and analytic. The wavelet filters constructed using the common-factor approach are then approximately analytic. Thus, it is of interest to control their analyticity. The purpose of this paper is to first provide precise and explicit expressions as well as easily exploitable bounds for quantifying the analytic approximation of this complex wavelet. Then, we prove the existence of such filters enjoying the classical perfect reconstruction conditions, with arbitrarily many vanishing moments.
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- 2020
16. Madelung transform and probability densities in hybrid quantum–classical dynamics
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Cesare Tronci, François Gay-Balmaz, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL), and Centre National de la Recherche Scientifique (CNRS)
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Applied Mathematics ,010102 general mathematics ,Dynamics (mechanics) ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,01 natural sciences ,Classical mechanics ,Geometric mechanics ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,Quantum hydrodynamics ,[MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph] ,0103 physical sciences ,0101 mathematics ,010306 general physics ,Moment map ,Quantum ,Mathematical Physics ,Mathematics - Abstract
Fully revised. To appear in Nonlinearity; International audience; This paper extends the Madelung-Bohm formulation of quantum mechanics to describe the time-reversible interaction of classical and quantum systems. The symplectic geometry of the Madelung transform leads to identifying hybrid classical-quantum Lagrangian paths extending the Bohmian trajectories from standard quantum theory. As the classical symplectic form is no longer preserved, the nontrivial evolution of the Poincar\'e integral is presented explicitly. Nevertheless, the classical phase-space components of the hybrid Bohmian trajectory identify a Hamiltonian flow parameterized by the quantum coordinate and this flow is associated to the motion of the classical subsystem. In addition, the continuity equation of the joint classical-quantum density is presented explicitly. While the von Neumann density operator of the quantum subsystem is always positive-definite by construction, the hybrid density is generally allowed to be unsigned. However, the paper concludes by presenting an infinite family of hybrid Hamiltonians whose corresponding evolution preserves the sign of the probability density for the classical subsystem.
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- 2020
17. Fluctuations for Spatially Extended Hawkes Processes
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Guilherme Ost, Julien Chevallier, Statistique pour le Vivant et l’Homme (SVH), Laboratoire Jean Kuntzmann (LJK), Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and Universidade Federal do Estado do Rio de Janeiro (UNIRIO)
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Statistics and Probability ,Mean field limit ,Applied Mathematics ,Probability (math.PR) ,010102 general mathematics ,Neural fields ,01 natural sciences ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,010104 statistics & probability ,Stochastic differential equation ,symbols.namesake ,Position (vector) ,Gaussian noise ,Modeling and Simulation ,FOS: Mathematics ,symbols ,Statistical physics ,Limit (mathematics) ,0101 mathematics ,Mathematics - Probability ,Mathematics ,Complement (set theory) ,Central limit theorem - Abstract
In a previous paper Chevallier et al. (2018), it has been shown that the mean-field limit of spatially extended Hawkes processes is characterized as the unique solution u ( t , x ) of a neural field equation (NFE). The value u ( t , x ) represents the membrane potential at time t of a typical neuron located in position x , embedded in an infinite network of neurons. In the present paper, we complement this result by studying the fluctuations of such a stochastic system around its mean field limit u ( t , x ) . Our first main result is a central limit theorem stating that the spatial distribution associated to these fluctuations converges to the unique solution of some stochastic differential equation driven by a Gaussian noise. In our second main result we show that the solutions of this stochastic differential equation can be well approximated by a stochastic version of the neural field equation satisfied by u ( t , x ) . To the best of our knowledge, this result appears to be new in the literature.
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- 2020
18. A new integral boundary control for de Saint-Venant Partial Differential Equations
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Vincent Andrieu, V. Dos Santos Martins, Cheng-Zhong Xu, Laboratoire d'automatique, de génie des procédés et de génie pharmaceutique (LAGEPP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Supérieure Chimie Physique Électronique de Lyon-Centre National de la Recherche Scientifique (CNRS), and Laboratoire d'automatique et de génie des procédés (LAGEP)
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0209 industrial biotechnology ,Saint venant ,Partial differential equation ,Forwarding ,010102 general mathematics ,Control (management) ,Lyapunov ,Integral controller ,Boundary (topology) ,02 engineering and technology ,Hyperbolic PDE ,Expression (computer science) ,01 natural sciences ,[SPI.AUTO]Engineering Sciences [physics]/Automatic ,020901 industrial engineering & automation ,Lyapunov functional ,Exponential growth ,Exponential stability ,Control and Systems Engineering ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,Applied mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,0101 mathematics ,Mathematics ,de Saint-Venant equations - Abstract
International audience; The paper deals with output feedback regulation of exponentially stable systems by an integral controller. We have recently proposed an appropriate Lyapunov functional to prove exponential stability of the closed-loop system. The approach is dedicated in this paper to hyperbolic systems and especially to the de Saint-Venant equations giving explicitly the gains to ensure an exponentially stabilized integral controller: the parameters expression is deduced directly of the Lyapunov functional based on the Forwarding approach. Numerical simulations illustrate this approach.
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- 2020
19. AN ENTROPIC INTERPOLATION PROBLEM FOR INCOMPRESSIBLE VISCOUS FLUIDS
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Ana Bela Cruzeiro, Christian Léonard, Jean-Claude Zambrini, Marc Arnaudon, Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS), Modélisation aléatoire de Paris X (MODAL'X), Université Paris Nanterre (UPN), Grupo de Fisica Matematica (GFMUL), Universidade de Lisboa = University of Lisbon (ULISBOA), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS), Departamento de Matemática IST (TUL) and GFMUL, Grupo de Física Matemática - Group of Mathematical Physics (GFM), Universidade de Lisboa (ULISBOA)-Universidade de Lisboa (ULISBOA), and Universidade de Lisboa (ULISBOA)
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Statistics and Probability ,Geodesic ,01 natural sciences ,Incompressible viscous fluids ,Physics::Fluid Dynamics ,010104 statistics & probability ,76D03 ,Inviscid flow ,Applied mathematics ,Entropy minimization ,28D20 ,0101 mathematics ,Diffusion processes ,Brownian motion ,Mathematics ,Stochastic velocities ,Convex duality ,010102 general mathematics ,49Q20 ,Function (mathematics) ,Absolute continuity ,49S05 ,Connection (mathematics) ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Convex optimization ,Relaxation (approximation) ,60G99 ,Statistics, Probability and Uncertainty - Abstract
In view of studying incompressible inviscid fluids, Brenier introduced in the late 80's a relaxation of a geodesic problem addressed by Arnold in 1966. Instead of inviscid fluids, the present paper is devoted to incompressible viscid fluids. A natural analogue of Brenier's problem is introduced, where generalized flows are no more supported by absolutely continuous paths, but by Brownian sample paths. It turns out that this new variational problem is an entropy minimization problem with marginal constraints entering the class of convex minimization problems. This paper explores the connection between this variational problem and Brenier's original problem. Its dual problem is derived and the general shape of its solution is described. Under the restrictive assumption that the pressure is a nice function, the kinematics of its solution is made explicit and its connection with the Navier-Stokes equation is established.
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- 2020
20. Convergence of a multidimensional Glimm-like scheme for the transport of fronts
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Olivier Hurisse, Thierry Gallouët, Aix Marseille Université (AMU), Mécanique des Fluides, Energies et Environnement (EDF R&D MFEE), EDF R&D (EDF R&D), and EDF (EDF)-EDF (EDF)
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Scheme (programming language) ,Convection ,Class (set theory) ,Advection ,Applied Mathematics ,General Mathematics ,Numerical analysis ,010102 general mathematics ,010103 numerical & computational mathematics ,Glimm’s scheme ,01 natural sciences ,Projection (linear algebra) ,multidimensional problem ,Computational Mathematics ,Convergence (routing) ,Applied mathematics ,random choice ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,front propagation ,Preprint ,0101 mathematics ,computer ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] ,Mathematics ,computer.programming_language - Abstract
International audience; This paper is devoted to the numerical analysis of a numerical scheme dedicated to the simulation of front advection (see https://hal.archives-ouvertes.fr/hal-02940407v1 for a preprint version presenting this scheme and some numerical results). The latter has been recently proposed and it is based on the ideas used for the Glimm's scheme. It relies on a two-step approach: a convection step is followed by a projection step which is based on a random choice. The main advantage of this scheme is that it applies to multi-dimensional problems. In the present paper a convergence result for this scheme is provided for a particular class of multi-dimensional problems. This work has been accepted for publication in IMA Journal of Numerical Analysis: https://doi.org/10.1093/imanum/drab053.
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- 2020
21. Flat inputs: theory and applications
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Florentina Nicolau, Jean-Pierre Barbot, Witold Respondek, Laboratoire QUARTZ (QUARTZ ), Université Paris 8 Vincennes-Saint-Denis (UP8)-SUPMECA - Institut supérieur de mécanique de Paris (SUPMECA)-Ecole Nationale Supérieure de l'Electronique et de ses Applications (ENSEA)-Ecole Internationale des Sciences du Traitement de l'Information (EISTI), Laboratoire de Mathématiques de l'INSA de Rouen Normandie (LMI), Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)
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0209 industrial biotechnology ,Control and Optimization ,Dynamical systems theory ,Applied Mathematics ,Flatness (systems theory) ,010102 general mathematics ,[MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS] ,Private communication ,02 engineering and technology ,constructing control vector fields ,01 natural sciences ,observed dynamical systems ,Flat inputs ,020901 industrial engineering & automation ,Control theory ,[MATH.MATH-DG]Mathematics [math]/Differential Geometry [math.DG] ,0101 mathematics ,[MATH]Mathematics [math] ,private communication ,Mathematics ,flatness - Abstract
In this paper, we study the problem of constructing flat inputs for multi-output dynamical systems. The notion of flat inputs has been introduced by Waldherr and Zeitz in [30, 31] and can be seen as dual to that of flat outputs. In the single-output case, a flat input can be constructed if and only if the original dynamical system together with its output is observable. In the multi-output case, the observability is not necessary for the existence of flat inputs. The observable case has been treated in [31], where a system of linear algebraic equations has been proposed in order to determine the control vector fields associated to the flat inputs. The goal of this paper is to treat the unobservable case for multi-output dynamical systems. We start by discussing the case when the dynamical system together with the given output is observable and we present a generalization of the results of [31] by relating them with the notion of minimal differential weight. Then we give our main results. We consider the unobservable case for which locally, on an open and dense subset of $\mathbb R^n$ , we construct control vector fields $g_1 , \ldots, g_m$ such that the associated control system is flat. Finally, we explain how our results can be applied to private communication.
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- 2020
22. A note on hypocoercivity for kinetic equations with heavy-tailed equilibrium
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Isabelle Tristani, Hélène Hivert, Maxime Herda, Nathalie Ayi, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Reliable numerical approximations of dissipative systems (RAPSODI ), Laboratoire Paul Painlevé - UMR 8524 (LPP), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Inria Lille - Nord Europe, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut Camille Jordan [Villeurbanne] (ICJ), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon, Département de Mathématiques et Applications - ENS Paris (DMA), École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS)
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Fokker-Planck operator ,General Mathematics ,010102 general mathematics ,fractional diffusion ,Kinetic energy ,82C40, 35K65, 35Q84, 60G22 ,01 natural sciences ,Hypocoercivity ,Mathematics - Analysis of PDEs ,Exponential growth ,Heavy-tailed distribution ,Kinetic equations ,Regularization (physics) ,0103 physical sciences ,Fractional diffusion ,FOS: Mathematics ,Applied mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,010307 mathematical physics ,0101 mathematics ,heavy-tailed distribution ,linear kinetic equations ,Mathematics ,Analysis of PDEs (math.AP) - Abstract
In this paper we are interested in the large time behavior of linear kinetic equations with heavy-tailed local equilibria. Our main contribution concerns the kinetic Lévy-Fokker-Planck equation, for which we adapt hypocoercivity techniques in order to show that solutions converge exponentially fast to the global equilibrium. Compared to the classical kinetic Fokker-Planck equation, the issues here concern the lack of symmetry of the non-local Lévy-Fokker-Planck operator and the understanding of its regularization properties. As a complementary related result, we also treat the case of the heavy-tailed BGK equation.; In this paper we are interested in the large time behavior of linear kinetic equations with heavy-tailed local equilib-ria. Our main contribution concerns the kinetic Lévy-Fokker-Planck equation, for which we adapt hypocoercivity techniques in order to show that solutions converge exponentially fast to the global equilibrium. Compared to the classical kinetic Fokker-Planck equation, the issues here concern the lack of symmetry of the non-local Lévy-Fokker-Planck operator and the understanding of its regularization properties. As a complementary related result, we also treat the case of the heavy-tailed BGK equation. Résumé Une note sur l'hypocoercivité pour leséquations cinétiques avecéquilibresà queue lourde. Dans cet article, on s'intéresse au comportement en temps long d'équations cinétiques linéaires dont leséquilibres locaux sontà queue lourde. Notre contribution principale concerne l'équation de Lévy-Fokker-Planck cinétique, pour laquelle nous adaptons des techniques d'hypocoercivité afin de démontrer la convergence exponentielle des solutions vers unéquilibre global. En comparant au cas de l'équation de Fokker-Planck cinétique classique, les enjeux ici sont liés au manque de symétrie de l'opérateur non-local de Lévy-Fokker-Planck età la compréhension de ses propriétés de régularisation. En complément de notre analyse, nous traitonségalement le cas de l'équation de BGKà queue lourde.
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- 2020
23. Online estimation of integrated squared density derivatives
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Abdelkader Mokkadem, Mariane Pelletier, Laboratoire de Mathématiques de Versailles (LMV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and We deeply thank the Referees for their thoughtful remarks, which led to a substantially improved version of our paper.
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Statistics and Probability ,Recursive estimation ,Mean squared error ,010102 general mathematics ,Bandwidth (signal processing) ,Estimator ,Probability density function ,Density estimation ,Online estimation ,Rate of convergence ,Stochastic algorithm ,01 natural sciences ,010104 statistics & probability ,Kernel estimators of integrals ,[MATH.MATH-ST]Mathematics [math]/Statistics [math.ST] ,Applied mathematics ,0101 mathematics ,Statistics, Probability and Uncertainty ,Mathematics ,Parametric statistics - Abstract
Hall and Marron (1987) introduced kernel estimators of integrals of the squared m -order derivatives of a probability density. Mokkadem and Pelletier (2020) gave recursive versions of their estimators, but the main drawback of these estimators is that their update requires the use of all past data. The aim of this paper is the study of online versions of the estimators introduced by Hall and Marron (1987), that is of estimators which are not only recursive, but which also have the property that their update uses only the last available data. Rates of convergence in mean squared error (MSE) are calculated. Similarly to the estimators of Hall and Marron (1987) and of Mokkadem and Pelletier (2020), our online estimators achieve the parametric rate n − 1 when m = 0 or when higher order kernels are used. For the case when the parametric rate is not obtained, we also study an online version of the estimator proposed by Jones and Sheather (1991). Finally, we provide recursive estimators of the optimal bandwidth in the framework of density estimation.
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- 2020
24. Regularization lemmas and convergence in total variation
- Author
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Lucia Caramellino, Guillaume Poly, Vlad Bally, Laboratoire Analyse et Mathématiques Appliquées (LAMA), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel, Mathematical Risk Handling (MATHRISK), Université Paris-Est Marne-la-Vallée (UPEM)-École des Ponts ParisTech (ENPC)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Dipartimento di Matematica [Rome], Università degli Studi di Roma Tor Vergata [Roma], Institut de Recherche Mathématique de Rennes (IRMAR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École normale supérieure - Rennes (ENS Rennes)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-INSTITUT AGRO Agrocampus Ouest, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Guillaume Poly is supported by the ANR grant UNIRANDOM., ANR-17-CE40-0008,UNIRANDOM,Universalité pour les domaines nodaux aléatoires(2017), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École normale supérieure - Rennes (ENS Rennes)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-INSTITUT AGRO Agrocampus Ouest, ANR-11-LABX-0020,LEBESGUE,Centre de Mathématiques Henri Lebesgue : fondements, interactions, applications et Formation(2011), Laboratoire d'Analyse et de Mathématiques Appliquées (LAMA), Université Paris-Est Marne-la-Vallée (UPEM)-Fédération de Recherche Bézout-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-AGROCAMPUS OUEST-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)
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Statistics and Probability ,Gaussian ,01 natural sciences ,010104 statistics & probability ,Total variation ,symbols.namesake ,60B110 ,60H07 ,abstract Malliavin calculus ,FOS: Mathematics ,Applied mathematics ,Integration by parts ,Wasserstein distance ,regularization techniques ,total variation distance ,0101 mathematics ,Mathematics ,Probability (math.PR) ,010102 general mathematics ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Formalism (philosophy of mathematics) ,Diffusion process ,Settore MAT/06 ,symbols ,Euler scheme ,Statistics, Probability and Uncertainty ,Random variable ,Mathematics - Probability - Abstract
We provide a simple abstract formalism of integration by parts under which we obtain some regularization lemmas. These lemmas apply to any sequence of random variables $(F_n)$ which are smooth and non-degenerated in some sense and enable one to upgrade the distance of convergence from smooth Wasserstein distances to total variation in a quantitative way. This is a well studied topic and one can consult for instance Bally and Caramellino [Electron. J. Probab. 2014], Bogachev, Kosov and Zelenov [Trans. Amer. Math. Soc. 2018], Hu, Lu and Nualart [J. Funct. Anal. 2014], Nourdin and Poly [Stoch. Proc. Appl. 2013] and the references therein for an overview of this issue. Each of the aforementioned references share the fact that some non-degeneracy is required along the whole sequence. We provide here the first result removing this costly assumption as we require only non-degeneracy at the limit. The price to pay is to control the smooth Wasserstein distance between the Malliavin matrix of the sequence and the Malliavin matrix of the limit which is particularly easy in the context of Gaussian limit as their Malliavin matrix is deterministic. We then recover, in a slightly weaker form, the main findings of Nourdin, Peccati and Swan [J. Funct. Anal. 2014]. Another application concerns the approximation of the semi-group of a diffusion process by the Euler scheme in a quantitative way and under the H\"ormander condition.
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- 2020
25. Mean Reflected Stochastic Differential Equations With Jumps
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Philippe Briand, Céline Labart, Abir Ghannoum, Laboratoire de Mathématiques (LAMA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Université Libanaise, and LABART, Celine
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Statistics and Probability ,Particle system ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,Applied Mathematics ,010102 general mathematics ,Probability (math.PR) ,Context (language use) ,Type (model theory) ,01 natural sciences ,Constraint (information theory) ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,010104 statistics & probability ,Stochastic differential equation ,Scheme (mathematics) ,FOS: Mathematics ,Applied mathematics ,Uniqueness ,0101 mathematics ,60Hxx ,Mathematics - Probability ,Mathematics - Abstract
This paper is devoted to the study of reflected Stochastic Differential Equations with jumps when the constraint is not on the paths of the solution but acts on the law of the solution. This type of reflected equations have been introduced recently by Briand, Elie and Hu [BEH18] in the context of BSDEs, when no jumps occur. In [BCdRGL16], the authors study a numerical scheme based on particle systems to approximate these reflected SDEs. In this paper, we prove existence and uniqueness of solutions to this kind of reflected SDEs with jumps and we generalize the results obtained in [BCdRGL16] to this context., Comment: arXiv admin note: substantial text overlap with arXiv:1612.06886
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- 2020
26. SELECTION OF EQUILIBRIA IN A LINEAR QUADRATIC MEAN-FIELD GAME
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François Delarue, Rinel Foguen Tchuendom, Laboratoire Jean Alexandre Dieudonné (JAD), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France, ANR-16-CE40-0015,MFG,Jeux Champs Moyen(2016), and ANR-19-P3IA-0002,3IA@cote d'azur,3IA Côte d'Azur(2019)
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Statistics and Probability ,Class (set theory) ,Mathematical optimization ,Computer Science::Computer Science and Game Theory ,Common noise ,media_common.quotation_subject ,Linear quadratic ,Selection of equilibria ,01 natural sciences ,2010 MSC. Primary: 60F17, 60H10, 91A13, 91A15. Secondary: 35L65 ,010104 statistics & probability ,Linear-quadratic control problem ,Component (UML) ,Transition point ,Mean-field game ,FOS: Mathematics ,Peano phenomenon ,Limit (mathematics) ,0101 mathematics ,Scalar conservation law ,Selection (genetic algorithm) ,media_common ,Mathematics ,Applied Mathematics ,010102 general mathematics ,Probability (math.PR) ,N -player game ,Infinity ,Zero (linguistics) ,Burgers equation ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Noise ,Modeling and Simulation ,Vanishing viscosity ,Entropy solution ,Mathematics - Probability - Abstract
International audience; In this paper, we address an instance of uniquely solvable mean-field game with a common noise whose corresponding counterpart without common noise has several equilib-ria. We study the selection problem for this mean-field game without common noise via three approaches. A common approach is to select, amongst all the equilibria, those yielding the minimal cost for the representative player. Another one is to select equilibria that are included in the support of the zero noise limit of the mean-field game with common noise. A last one is to select equilibria supported by the limit of the mean-field component of the corresponding N-player game as the number of players goes to infinity. The contribution of this paper is to show that, for the class under study, the last two approaches select the same equilibria, but the first approach selects another one.
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- 2020
27. Homogenization of a stochastic viscous transport equation
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Nicolas Forcadel, Ioana Ciotir, Wilfredo Salazar, Laboratoire de Mathématiques de l'INSA de Rouen Normandie (LMI), Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)
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Homogenization ,Control and Optimization ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,01 natural sciences ,Homogenization (chemistry) ,010101 applied mathematics ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,stochastic transport equation ,Modeling and Simulation ,mild solution ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,Uniqueness ,0101 mathematics ,Convection–diffusion equation ,Mathematics - Abstract
In the present paper we prove an homogenisation result for a locally perturbed transport stochastic equation. The model is similar to the stochastic Burgers' equation and it is inspired by the LWR model. Therefore, the interest in studying this equation comes from it's application for traffic flow modelling. In the first part of paper we study the inhomogeneous equation. More precisely we give an existence and uniqueness result for the solution. The technical difficulties of this part come from the presence of the function \begin{document}$ \varphi $\end{document} under assumptions coherent for the model, which is giving the inhomogeneity with respect to the space variable, not present in the classical results. The second part of the paper is the homogenisation result in space.
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- 2020
28. Lubrication and shallow-water systems, Bernis-Friedman and BD entropies
- Author
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Didier Bresch, Pascal Noble, Mathieu Colin, Khawla Msheik, Xi Song, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria), Certified Adaptive discRete moDels for robust simulAtions of CoMplex flOws with Moving fronts (CARDAMOM), Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Institut National des Sciences Appliquées (INSA), and Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS)-Inria Bordeaux - Sud-Ouest
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T57-57.97 ,Applied mathematics. Quantitative methods ,010102 general mathematics ,Type (model theory) ,bd and bf entropies ,01 natural sciences ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,Compact space ,Drag ,0103 physical sciences ,Dissipative system ,Lubrication ,Compressibility ,QA1-939 ,Applied mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,lubrication and shallow-water models ,global weak solutions ,Limit (mathematics) ,0101 mathematics ,Entropy (arrow of time) ,Mathematics ,ComputingMilieux_MISCELLANEOUS - Abstract
This paper concerns the results recently announced by the authors, in C.R. Acad. Sciences Maths volume 357, Issue 1, 1-6 (2019), which make the link between the BD entropy introduced by D. Bresch and B. Desjardins for the viscous shallow-water equations and the Bernis-Friedman (called BF in our paper) dissipative entropy introduced to study the lubrication equations. More precisely different dissipative BF entropies are obtained from the BD entropies playing with drag terms and capillarity formula for viscous shallow water type equations. This is the main idea in the paper which makes the link between two communities. The limit processes employ the standard compactness arguments taking care of the control in the drag terms. It allows in one dimension for instance to prove global existence of nonnegative weak solutions for lubrication equations starting from the global existence of nonnegative weak solutions for appropriate viscous shallow-water equations (for which we refer to appropriate references). It also allows to prove global existence of nonnegative weak solutions for fourth-order equation including the Derrida-Lebowitz-Speer-Spohn equation starting from compressible Navier-Stokes type equations.
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- 2020
29. Rates of convergence in invariance principles for random walks on linear groups via martingale methods
- Author
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Christophe Cuny, Florence Merlevède, Jérôme Dedecker, Laboratoire de Mathématiques de Bretagne Atlantique (LMBA), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Mathématiques Appliquées Paris 5 (MAP5 - UMR 8145), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Mathématiques et de leurs Interactions (INSMI)-Université Paris Descartes - Paris 5 (UPD5), Laboratoire d'Analyse et de Mathématiques Appliquées (LAMA), Université Paris-Est Marne-la-Vallée (UPEM)-Fédération de Recherche Bézout-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Paris Descartes - Paris 5 (UPD5)-Institut National des Sciences Mathématiques et de leurs Interactions (INSMI)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Fédération de Recherche Bézout-Université Paris-Est Marne-la-Vallée (UPEM), and Université de Brest (UBO)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)
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Vector-valued martingales ,Pure mathematics ,Markov chain ,Invariance principle ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Probability (math.PR) ,Lie group ,Random walk ,01 natural sciences ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,010104 statistics & probability ,Mathematics::Probability ,Strong invariance principle ,Iwasawa cocycle ,FOS: Mathematics ,Wasserstein distances ,Cartan projection ,0101 mathematics ,Martingale (probability theory) ,Random walks ,Mathematics - Probability ,Central limit theorem ,Mathematics - Abstract
In this paper, we give explicit rates in the central limit theorem and in the almost sure invariance principle for general R d {\mathbb R}^d -valued cocycles that appear in the study of the left random walk on linear groups. Our method of proof lies on a suitable martingale approximation and on a careful estimation of some coupling coefficients linked with the underlying Markov structure. Concerning the martingale part, the available results in the literature are not accurate enough to give almost optimal rates either in the central limit theorem for the Wasserstein distance, or in the strong approximation. A part of this paper is devoted to circumvent this issue. We then exhibit near optimal rates both in the central limit theorem in terms of the Wasserstein distance and in the almost sure invariance principle for R d {\mathbb R}^d -valued martingales with stationary increments having moments of order p ∈ ( 2 , 3 ] p \in (2, 3] (the case of sequences of reversed martingale differences is also considered). Note also that, as an application of our results for general R d {\mathbb R}^d -valued cocycles, a special attention is paid to the Iwasawa cocycle and the Cartan projection for reductive Lie groups (like for instance G L d ( R ) {\mathrm {GL}}_d(\mathbb {R}) ).
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- 2019
30. Asymptotic Behavior for Textiles
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Julia Orlik, Georges Griso, Stephan Wackerle, Laboratoire Jacques-Louis Lions (LJLL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Fraunhofer Institute of Industrial Mathematics (Fraunhofer ITWM), Fraunhofer (Fraunhofer-Gesellschaft), Griso, Georges, and Publica
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dimension reduction ,74K10 ,variational inequality ,01 natural sciences ,Homogenization (chemistry) ,Physics::Popular Physics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,0101 mathematics ,[MATH.MATH-AP] Mathematics [math]/Analysis of PDEs [math.AP] ,Mathematics ,47H05 ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Linear elasticity ,linear elasticity ,[MATH.MATH-NA] Mathematics [math]/Numerical Analysis [math.NA] ,35J86 ,74B05 ,periodic unfolding method ,74K20 ,010101 applied mathematics ,Computational Mathematics ,plates ,structure of beams Mathematics Subject Classification (2010): 35B27 ,Keyword: Homogenization ,Variational inequality ,MSC (2010): 35B27, 35J86, 47H05, 74Q05, 74B05, 74K10, 74K20 ,Physics::Accelerator Physics ,Leray-Lions problem ,Analysis ,contact ,74Q05 ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] - Abstract
The paper is dedicated to the asymptotic investigation of textiles as an elasticity problem on beam structures. The structure is subjected to a simultaneous homogenization and dimension reduction with respect to the asymptotic behavior of the beams' thickness and periodicity. Important for the problem are the contact conditions between the beams, which yield multiple limits depending on the order. In this paper two limiting cases are presented: a linear case and a Leray-Lions-type problem.
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- 2019
31. Garamon: A Geometric Algebra Library Generator
- Author
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Vincent Nozick, Stéphane Breuils, Laurent Fuchs, Laboratoire d'Informatique Gaspard-Monge (LIGM), Centre National de la Recherche Scientifique (CNRS)-Fédération de Recherche Bézout-ESIEE Paris-École des Ponts ParisTech (ENPC)-Université Paris-Est Marne-la-Vallée (UPEM), Japanese French Laboratory for Informatics (JFLI), National Institute of Informatics (NII)-The University of Tokyo (UTokyo)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), SIC, XLIM (XLIM), and Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers
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Multivector ,Prefix tree ,Applied Mathematics ,010102 general mathematics ,Clifford algebra ,Geometric Algebra ,Python (programming language) ,Data structure ,01 natural sciences ,Software implementation ,Algebra ,Clifford Algebra ,Geometric algebra ,0103 physical sciences ,Trie ,010307 mathematical physics ,0101 mathematics ,computer ,Vector space ,Mathematics ,computer.programming_language ,[INFO.INFO-MS]Computer Science [cs]/Mathematical Software [cs.MS] - Abstract
International audience; This paper presents both a recursive scheme to perform Geometric Algebra operations over a prefix tree, and Garamon, a C++ library generator implementing these recursive operations. While for low dimension vector spaces, precomputing all the Geometric Algebra products is an efficient strategy, it fails for higher dimensions where the operation should be computed at run time. This paper describes how a prefix tree can be a support for a recursive formulation of Geometric Algebra operations. This recursive approach presents a much better complexity than the usual run time methods. This paper also details how a prefix tree can represent efficiently the dual of a multivector. These results constitute the foundations for Garamon, a C++ library generator synthesizing efficient C++ / Python libraries implementing Geometric Algebra in both low and higher dimensions, with any arbitrary metric. Garamon takes advantage of the prefix tree formulation to implement Geometric Algebra operations on high dimensions hardly accessible with state-of-the-art software implementations. Garamon is designed to produce easy to install , easy to use, effective and numerically stable libraries. The design of the libraries is based on a data structure using precomputed functions for low dimensions and a smooth transition to the new recursive products for higher dimensions. Mathematics Subject Classification (2010). Primary 99Z99; Secondary 00A00.
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- 2019
32. Shape and size dependence of dipolar plasmonic resonance of nanoparticles
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Habib Ammari, Pierre Millien, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut Langevin - Ondes et Images (UMR7587) (IL), Sorbonne Université (SU)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Paris (UP)-Centre National de la Recherche Scientifique (CNRS)
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General Mathematics ,FOS: Physical sciences ,Nanoparticle ,01 natural sciences ,Mathematics - Spectral Theory ,Mathematics - Analysis of PDEs ,[MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph] ,FOS: Mathematics ,0101 mathematics ,Absorption (electromagnetic radiation) ,Spectral Theory (math.SP) ,Size dependence ,Mathematical Physics ,Plasmon ,Mathematics ,volume integral equation ,[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics] ,Condensed matter physics ,Applied Mathematics ,010102 general mathematics ,plasmonic resonance ,Resonance ,Mathematical Physics (math-ph) ,010101 applied mathematics ,Dipole ,Extinction (optical mineralogy) ,MSC 2000: 35R30, 35C20 ,singular integrals ,Quasistatic process ,Analysis of PDEs (math.AP) - Abstract
International audience; The aim of this paper is to present a new approach, based on singular volume integral equations and a perturbative approach in order to compute the size dependency of plasmonic resonances of metallic nanoparticles when the quasistatic regime is no longer valid. The paper also provides rigorous derivations of the extinction and absorption cross sections for elliptical particles.; Cet article présente une nouvelle méthode pour l'étude de la dépendance des fréquences de résonances plasmoniques des nano-particules métalliques dans un régime où l'approximation quasistatique n'est plus valide. Ces travaux reposent sur l'étude du spectre d'un opérateur integral singulier ainsi que sur l'application d'une méthode perturbative.
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- 2019
33. Equilibrium problems in weakly admissible external fields created by pointwise charges
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J.F. Sánchez Lara, Ramón Orive, Franck Wielonsky, Institut de Mathématiques de Marseille (I2M), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Universidad de La Laguna [Tenerife - SP] (ULL), and Universidad de Granada = University of Granada (UGR)
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Pointwise ,Numerical Analysis ,Pure mathematics ,Mathematics - Complex Variables ,Applied Mathematics ,General Mathematics ,media_common.quotation_subject ,010102 general mathematics ,010103 numerical & computational mathematics ,Infinity ,01 natural sciences ,Measure (mathematics) ,Potential theory ,Compact space ,Simple (abstract algebra) ,FOS: Mathematics ,Uniqueness ,Complex Variables (math.CV) ,0101 mathematics ,[MATH]Mathematics [math] ,Complex plane ,Analysis ,ComputingMilieux_MISCELLANEOUS ,Mathematics ,media_common - Abstract
The main subject of this paper is equilibrium problems on an unbounded conductor $\Sigma$ of the complex plane in the presence of a weakly admissible external field. An admissible external field $Q$ on $\Sigma$ satisfies, along with other mild conditions, the following growth property at infinity: $$\lim_{|x| \rightarrow \infty}(Q(x) - \log |x|) = +\infty.$$ This condition guarantees the existence and uniqueness of the equilibrium measure in the presence of $Q$, and the compactness of its support. In the last 10-15 years, several papers have dealt with weakly admissible external fields, in the sense that $Q$ satisfies a weaker condition at infinity, namely, $$\exists M\in(-\infty,\infty],\quad\liminf_{|x| \rightarrow \infty}(Q(x) - \log |x|) = M.$$ Under this last assumption, there still exists a unique equilibrium measure in the external field $Q$, but the support need not be a compact subset of $\Sigma$ anymore. In most examples considered in the literature the support is indeed unbounded. Our main goal in this paper is to illustrate this topic by means of a simple class of external fields on the real axis created by a pair of attractive and repellent charges in the complex plane, and to study the dynamics of the associated equilibrium measures as the strength of the charges evolves. As one of our findings, we exhibit configurations where the support of the equilibrium measure in a weakly admissible external field is a compact subset of the real axis. To achieve our goal, we extend some results from potential theory, known for admissible external fields, to the weakly admissible case. These new results may be of independent interest. Finally, the so--called signed equilibrium measure is an important tool in our analysis. Its relationship with the (positive) equilibrium measure is also explored., Comment: To appear in Journal of Approximation Theory
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- 2019
34. Simple Forms and Rational Solutions of Pseudo-Linear Systems
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Moulay A. Barkatou, Thomas Cluzeau, Ali El Hajj, Mathématiques & Sécurité de l'information (XLIM-MATHIS), XLIM (XLIM), and Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)
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Maple ,Computation ,010102 general mathematics ,Linear system ,0102 computer and information sciences ,engineering.material ,Symbolic computation ,01 natural sciences ,Reduction (complexity) ,010201 computation theory & mathematics ,Simple (abstract algebra) ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,engineering ,Applied mathematics ,0101 mathematics ,Differential (infinitesimal) ,[MATH]Mathematics [math] ,ComputingMilieux_MISCELLANEOUS ,Mathematics - Abstract
In this paper, we first provide a unified algorithm for computing simple forms for systems of pseudo-linear equations. We prove that the existing methods for linear differential and difference systems can be extended to handle more general pseudo-linear systems. We explain how the reduction to a simple form can be used to compute efficiently local data for a system of pseudo-linear equations. We then propose an alternative, again based on simple forms, to previous algorithms for computing rational solutions of pseudo-linear systems. Moreover we develop a new algorithm for computing rational solutions of systems in two variables composed of linear differential and difference equations. Finally, we show that this algorithm can be generalized to the case of a system of partial pseudo-linear equations. All the algorithms described in this paper have been implemented in Maple and some examples of computations are provided.
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- 2019
35. Localization of eigenfunctions via an effective potential
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Svitlana Mayboroda, Douglas N. Arnold, Guy David, David Jerison, Marcel Filoche, School of Mathematics (UMN-MATH), University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Laboratoire de Mathématiques d'Orsay (LM-Orsay), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique de la matière condensée (LPMC), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Massachusetts Institute of Technology (MIT), and Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)
- Subjects
Applied Mathematics ,Operator (physics) ,010102 general mathematics ,Spectrum (functional analysis) ,Mathematical analysis ,Boundary (topology) ,35P, 35Q40 ,Mathematics::Spectral Theory ,Eigenfunction ,01 natural sciences ,[SDV.MHEP.PSR]Life Sciences [q-bio]/Human health and pathology/Pulmonology and respiratory tract ,010101 applied mathematics ,Mathematics - Analysis of PDEs ,Lipschitz domain ,FOS: Mathematics ,[SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic ,Boundary value problem ,[PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn] ,0101 mathematics ,Exponential decay ,[PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] ,Analysis ,Eigenvalues and eigenvectors ,Analysis of PDEs (math.AP) ,Mathematics - Abstract
We consider the localization of eigenfunctions for the operator $L=-\mbox{div} A \nabla + V$ on a Lipschitz domain $\Omega$ and, more generally, on manifolds with and without boundary. In earlier work, two authors of the present paper demonstrated the remarkable ability of the landscape, defined as the solution to $Lu=1$, to predict the location of the localized eigenfunctions. Here, we explain and justify a new framework that reveals a richly detailed portrait of the eigenfunctions and eigenvalues. We show that the reciprocal of the landscape function, $1/u$, acts as an effective potential. Hence from the single measurement of $u$, we obtain, via $1/u$, explicit bounds on the exponential decay of the eigenfunctions of the system and estimates on the distribution of eigenvalues near the bottom of the spectrum. (This version strengthens and simplifies the results of the first one by replacing a global bi-Lipschitz hypothesis on the domain with a local bi-Lipschitz hypothesis. It improves on the second version by adding pictures and numerical examples. This version is identical to the third version; all that is changed is to correct some tex mistakes in symbols in this abstract. There are no changes to the paper itself.), Comment: 33 pages
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- 2019
36. Uniqueness of the nonlinear Schrödinger equation driven by jump processes
- Author
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Martin Ondreját, Erika Hausenblas, Anne de Bouard, Centre de Mathématiques Appliquées - Ecole Polytechnique (CMAP), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Montanuniversität Leoben (MUL), Institute of Information Theory and Automation of the Czech Academy of Sciences (UTIA / CAS), and Czech Academy of Sciences [Prague] (CAS)
- Subjects
Applied Mathematics ,010102 general mathematics ,01 natural sciences ,Strong solutions ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,010104 statistics & probability ,Levy noise ,symbols.namesake ,Mathematics::Probability ,Jump ,symbols ,Applied mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,Uniqueness ,0101 mathematics ,Martingale (probability theory) ,Nonlinear Schrödinger equation ,Analysis ,ComputingMilieux_MISCELLANEOUS ,Mathematics - Abstract
In a recent paper by the first two authors, existence of martingale solutions to a stochastic nonlinear Schrodinger equation driven by a Levy noise was proved. In this paper, we prove pathwise uniqueness, uniqueness in law and existence of strong solutions to this problem using an abstract uniqueness result of Kurtz.
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- 2019
37. A differential equation approach to implicit sweeping processes
- Author
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Abderrahim Jourani, Emilio Vilches, Institut de Mathématiques de Bourgogne [Dijon] (IMB), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université de Bourgogne (UB), Instituto de Ciencias de la educacion (ICEd - UOH), Universidad de O'Higgins (UOH), and Conicyt Math-AmSud 17-MATH-06 Redes REDI170200
- Subjects
Lyapunov function ,Differential equation ,01 natural sciences ,law.invention ,symbols.namesake ,Evolution variational inequality ,law ,Applied mathematics ,Uniqueness ,0101 mathematics ,Equivalence (formal languages) ,[MATH]Mathematics [math] ,Mathematics ,Convex analysis ,Applied Mathematics ,010102 general mathematics ,Nonsmooth Lyapunov pairs ,010101 applied mathematics ,regularization ,MSC: 49J40, 47J20, 47J22, 34G25, 58E35, 37L45 ,Electrical network ,Variational inequality ,symbols ,Moreau's sweeping process ,Analysis ,Quasistatic process - Abstract
International audience; In this paper, we study an implicit version of the sweeping process. Based on methods of convex analysis, we prove the equivalence of the implicit sweeping process with a differential equation, which enables us to show the existence and uniqueness of the solution to the implicit sweeping process in a very general framework. Moreover, this equivalence allows us to give a characterization of nonsmooth Lyapunov pairs and invariance for implicit sweeping processes. The results of the paper are illustrated with two applications to quasistatic evolution variational inequalities and electrical circuits.
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- 2019
38. Hardy-Sobolev inequalities with singularities on non smooth boundary: Hardy constant and extremals. Part I: Influence of local geometry
- Author
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Hussein Cheikh Ali, Département de mathématiques Université Libre de Bruxelles, and Université libre de Bruxelles (ULB)
- Subjects
Mean curvature ,Applied Mathematics ,010102 general mathematics ,Geometry ,Conical surface ,Non smooth ,01 natural sciences ,Sobolev inequality ,010101 applied mathematics ,Mathématiques ,Singularity ,Norm (mathematics) ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,Gravitational singularity ,0101 mathematics ,Analyse mathématique ,Analysis ,Interior point method ,Mathematics - Abstract
Let Ω be a domain of R n , n ≥ 3 . The classical Caffarelli–Kohn–Nirenberg inequality rewrites as the following inequality: for any s ∈ [ 0 , 2 ] and any γ ( n − 2 ) 2 4 , there exists a constant K ( Ω , γ , s ) > 0 such that ( H S ) ∫ Ω | u | 2 ⋆ ( s ) | x | s d x 2 2 ⋆ ( s ) ≤ K ( Ω , γ , s ) ∫ Ω | ∇ u | 2 − γ u 2 | x | 2 d x , for all u ∈ D 1 , 2 ( Ω ) (the completion of C c ∞ ( Ω ) for the relevant norm). When 0 ∈ Ω is an interior point, the range ( − ∞ , ( n − 2 ) 2 4 ) for γ cannot be improved: moreover, the optimal constant K ( Ω , γ , s ) is independent of Ω and there is no extremal for ( H S ) . But when 0 ∈ ∂ Ω , the situation turns out to be drastically different since the geometry of the domain impacts : • the range of γ ’s for which ( H S ) holds. • the value of the optimal constant K ( Ω , γ , s ) ; • the existence of extremals for ( H S ) . When Ω is smooth, the problem was tackled by Ghoussoub–Robert (2017) where the role of the mean curvature was central. In the present paper, we consider nonsmooth domain with a singularity at 0 modeled on a cone. We show how the local geometry induced by the cone around the singularity influences the value of the Hardy constant on Ω . When γ is small, we introduce a new geometric object at the conical singularity that generalizes the ”mean curvature”: this allows to get extremals for ( H S ) . The case of larger values for γ will be dealt in the forthcoming paper (Cheikh-Ali, 2018). As an intermediate result, we prove the symmetry of some solutions to singular pdes that has an interest on its own.
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- 2019
39. Existence of strong minimizers for the Griffith static fracture model in dimension two
- Author
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Sergio Conti, Matteo Focardi, Flaviana Iurlano, Institut fur Angewandte Mathematik (Institut fur Angewandte Mathematik), Rheinische Friedrich-Wilhelms-Universität Bonn, Dipartimento di Matematica 'Ulisse Dini', Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Laboratoire Jacques-Louis Lions (LJLL), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
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Pure mathematics ,Generalization ,Applied Mathematics ,010102 general mathematics ,Dimension (graph theory) ,Elasticity (physics) ,Type (model theory) ,16. Peace & justice ,01 natural sciences ,010101 applied mathematics ,Sobolev space ,Set (abstract data type) ,Mathematics - Analysis of PDEs ,Existence, strong minimizers, Griffith static fracture modeL, dimension two ,Jump ,FOS: Mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,Coarea formula ,0101 mathematics ,[MATH]Mathematics [math] ,Mathematical Physics ,Analysis ,ComputingMilieux_MISCELLANEOUS ,Mathematics ,Analysis of PDEs (math.AP) - Abstract
We consider the Griffith fracture model in two spatial dimensions, and prove existence of strong minimizers, with closed jump set and continuously differentiable deformation fields. One key ingredient, which is the object of the present paper, is a generalization to the vectorial situation of the decay estimate by De Giorgi, Carriero, and Leaci. This is based on replacing the coarea formula by a method to approximate S B D p functions with small jump set by Sobolev functions, and is restricted to two dimensions. The other two ingredients will appear in companion papers and consist respectively in regularity results for vectorial elliptic problems of the elasticity type and in a method to approximate in energy G S B D p functions by S B V p ones.
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- 2019
40. Remainder Padé approximants for hypergeometric series
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Tanguy Rivoal, Marc Prévost, Université du Littoral Côte d'Opale (ULCO), Institut Fourier (IF ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université du Littoral Côte d'Opale, Institut Fourier (IF), and Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)
- Subjects
Series (mathematics) ,Mathematics::Complex Variables ,Applied Mathematics ,010102 general mathematics ,Mathematics::Classical Analysis and ODEs ,010103 numerical & computational mathematics ,Term (logic) ,01 natural sciences ,[MATH.MATH-NT]Mathematics [math]/Number Theory [math.NT] ,Mathematics::Numerical Analysis ,Nonlinear Sciences::Chaotic Dynamics ,Condensed Matter::Statistical Mechanics ,Applied mathematics ,Padé approximant ,0101 mathematics ,Hypergeometric function ,Remainder ,Asymptotic expansion ,Analysis ,[MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA] ,Mathematics ,Variable (mathematics) - Abstract
Remainder Padé Approximation (RPA) consists in adding to the n-th partial sum of a series a suitable Padé approximant of the asymptotic expansion in the variable 1/n of the remainder term. In a previous paper, we proved the non-trivial property that the RPA of the exponential function is identical to the Padé approximant to the exponential function. In this paper, we extend this property to the hypergeometric series 1F1(1; a; z) and 2F0(b, 1; z).
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- 2019
41. Existence of strong solutions to the Dirichlet problem for the Griffith energy
- Author
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Vito Crismale, Antonin Chambolle, Centre de Mathématiques Appliquées - Ecole Polytechnique (CMAP), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
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Pure mathematics ,regularity ,Mathematics::Analysis of PDEs ,01 natural sciences ,Brittle fracture ,minimisation ,strong solutions ,generalised special functions of bounded deformation ,Dirichlet distribution ,Strong solutions ,symbols.namesake ,Mathematics - Analysis of PDEs ,FOS: Mathematics ,[MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP] ,0101 mathematics ,Mathematics ,Dirichlet problem ,Applied Mathematics ,010102 general mathematics ,MSC. 49Q20 49N60 35R35 26A45 74R10 ,010101 applied mathematics ,Dirichlet boundary condition ,Poincaré conjecture ,symbols ,Jump ,Analysis ,Non lineaire ,Analysis of PDEs (math.AP) - Abstract
In this paper we continue the study of the Griffith brittle fracture energy minimisation under Dirichlet boundary conditions, suggested by Francfort and Marigo (J Mech Phys Solids 46:1319–1342, 1998). In a recent paper (Chambolle and Crismale in J Eur Math Soc (JEMS), 2018) we proved the existence of weak minimisers of the problem. Now we show that these minimisers are indeed strong solutions, namely their jump set is closed and they are smooth away from the jump set and continuous up to the Dirichlet boundary. This is obtained by extending up to the boundary the recent regularity results of Conti et al. (Ann Inst H Poincare Anal Non Lineaire 36:455–474, 2019) and Chambolle et al. (J Math Pures Appl, 2019. https://doi.org/10.1016/j.matpur.2019.02.001 ).
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- 2019
42. Pontryagin maximum principle for general Caputo fractional optimal control problems with Bolza cost and terminal constraints
- Author
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Loïc Bourdin, Maïtine Bergounioux, Bergounioux, Maïtine, Institut Denis Poisson (IDP), Centre National de la Recherche Scientifique (CNRS)-Université de Tours-Université d'Orléans (UO), Mathématiques & Sécurité de l'information (XLIM-MATHIS), XLIM (XLIM), Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Université d'Orléans (UO)
- Subjects
Filippov's existence theorem ,0209 industrial biotechnology ,Control and Optimization ,Transversality ,02 engineering and technology ,Hamiltonian maximization condition ,fractional calculus ,01 natural sciences ,Convexity ,Hamiltonian system ,020901 industrial engineering & automation ,Variational principle ,Pontryagin maximum principle ,Applied mathematics ,0101 mathematics ,Mathematics ,Mathematics Subject Classification. 34K35 ,26A33 ,34A08 ,49J15 ,49K40 ,93C15 ,needle-like variations ,010102 general mathematics ,transversality conditions ,Ekeland's variational principle ,[MATH.MATH-OC] Mathematics [math]/Optimization and Control [math.OC] ,Optimal control ,Riemann-Liouville and Caputo operators ,Fractional calculus ,Computational Mathematics ,Control and Systems Engineering ,adjoint vector ,[MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC] ,Hamiltonian (control theory) - Abstract
In this paper we focus on a general optimal control problem involving a dynamical system described by a nonlinear Caputo fractional differential equation of order 0 α≤ 1, associated to a general Bolza cost written as the sum of a standard Mayer cost and a Lagrange cost given by a Riemann-Liouville fractional integral of order β ≥α. In addition the present work handles general control and mixed initial/final state constraints. Adapting the standard Filippov's approach based on appropriate compactness assumptions and on the convexity of the set of augmented velocities, we give an existence result for at least one optimal solution. Then, the major contribution of this paper is the statement of a Pontryagin maximum principle which provides a first-order necessary optimality condition that can be applied to the fractional framework considered here. In particular, Hamiltonian maximization condition and transversality conditions on the adjoint vector are derived. Our proof is based on the sensitivity analysis of the Caputo fractional state equation with respect to needle-like control perturbations and on Ekeland's variational principle. The paper is concluded with two illustrating examples and with a list of several perspectives for forthcoming works.
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- 2019
43. Restoring discrete Painlevé equations from an E$_8^{(1)}$-associated one
- Author
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Ralph Willox, B. Grammaticos, A. Ramani, Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC (UMR_8165)), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[PHYS]Physics [physics] ,Variables ,Nonlinear Sciences - Exactly Solvable and Integrable Systems ,media_common.quotation_subject ,010102 general mathematics ,Process (computing) ,Statistical and Nonlinear Physics ,Type (model theory) ,01 natural sciences ,Nonlinear differential equations ,0103 physical sciences ,Applied mathematics ,Canonical form ,010307 mathematical physics ,Limit (mathematics) ,0101 mathematics ,Mathematical Physics ,Mathematics ,media_common - Abstract
We present a systematic method for the construction of discrete Painlev\'e equations. The method, dubbed `restoration', allows one to obtain all discrete Painlev\'e equations that share a common autonomous limit, up to homographic transformations, starting from any one of those limits. As the restoration process crucially depends on the classification of canonical forms for the mappings in the QRT family, it can in principle only be applied to mappings that belong to that family. However, as we show in this paper, it is still possible to obtain the results of the restoration even when the initial mapping is not of QRT type (at least for the system at hand, but we believe our approach to be of much wider applicability). For the equations derived in this paper we also show how, starting from a form where the independent variable advances one step at a time, one can obtain versions corresponding to multistep evolutions., Comment: 17 pages, 1 figure
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- 2019
44. Measure and capacity of wandering domains in Gevrey near-integrable exact symplectic systems
- Author
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Laurent Lazzarini, Jean-Pierre Marco, David Sauzin, Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Fibonacci, Scuola Normale Superiore di Pisa (SNS)-Centro di Ricerca Matematica Ennio De Giorgi-Centre National de la Recherche Scientifique (CNRS), and Sauzin, David
- Subjects
Connected space ,Pure mathematics ,Mathematics::Dynamical Systems ,General Mathematics ,[MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS] ,[MATH.MATH-DS] Mathematics [math]/Dynamical Systems [math.DS] ,Dynamical Systems (math.DS) ,01 natural sciences ,Upper and lower bounds ,Nekhoroshev theorem ,Arnold diffusion ,FOS: Mathematics ,Gevrey functions ,Mathematics - Dynamical Systems ,0101 mathematics ,Mathematics::Symplectic Geometry ,Mathematics ,Kolmogorov–Arnold–Moser theorem ,Applied Mathematics ,010102 general mathematics ,Wandering set ,Hamiltonian perturbation theory ,Iterated function ,exact symplectic map ,Diffeomorphism ,wandering set ,Symplectic geometry - Abstract
DOI: https://doi.org/10.1090/memo/1235; International audience; A wandering domain for a diffeomorphism is an open connected set whose iterates are pairwise disjoint. We endow A^n = T^n x R^n with its usual exact symplectic structure. An integrable diffeomorphism Φ^h, i.e. the time-one map of a Hamiltonian h which depends only on the action variables, has no nonempty wandering domains. The aim of this paper is to estimate the size (measure and Gromov capacity) of wandering domains in the case of an exact symplectic perturbation of Φ^h , in the analytic or Gevrey category. Upper estimates are related to Nekhoroshev theory, lower estimates are related to examples of Arnold diffusion. This is a contribution to the "quantitative Hamiltonian perturbation theory" initiated in previous works on the optimality of long term stability estimates and diffusion times; our emphasis here is on discrete systems because this is the natural setting to study wandering domains. We first prove that the measure (or the capacity) of these wandering domains is exponentially small, with an upper bound of the form exp(-c ε^(-1/2nα)), where ε is the size of the perturbation, α is the Gevrey exponent (α is at least 1, α=1 for analytic systems) and c is some positive constant depending mildly on h. This is obtained as a consequence of an exponential stability theorem for near-integrable exact symplectic maps, in the analytic or Gevrey category, for which we give a complete proof based on the most recent improvements of Nekhoroshev theory for Hamiltonian flows, and which requires the development of specific Gevrey suspension techniques. The second part of the paper is devoted to the construction of near-integrable Gevrey systems possessing wandering domains, for which the capacity (and thus the measure) can be estimated from below. We suppose that n is at least 2, essentially because KAM theory precludes Arnold diffusion in too low a dimension. For any α>1, we produce examples with lower bounds of the form exp(-c ε^(-1/2(n-1)(α-1))). This is done by means of a "coupling" technique, involving rescaled standard maps possessing wandering discs in A and near-integrable systems possessing periodic domains of arbitrarily large periods in A^(n-1). The most difficult part of the construction consists in obtaining a perturbed pendulum-like system on A with periodic islands of arbitrarily large periods, whose areas are explicitly estimated from below. Our proof is based on a version due to Herman of the translated curve theorem.
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- 2019
45. Representation of lattices via set-colored posets
- Author
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Michel Habib, Lhouari Nourine, Institut de Recherche en Informatique Fondamentale (IRIF (UMR_8243)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Networks, Graphs and Algorithms (GANG), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Laboratoire d'Informatique, de Modélisation et d'Optimisation des Systèmes (LIMOS), Ecole Nationale Supérieure des Mines de St Etienne-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Ecole Nationale Supérieure des Mines de St Etienne (ENSM ST-ETIENNE)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), and Ecole Nationale Supérieure des Mines de St Etienne-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Antimatroid ,Set-colored poset ,Applied Mathematics ,High Energy Physics::Lattice ,010102 general mathematics ,Lattice ,Representation theory ,Upper locally distributive lattice ,0102 computer and information sciences ,[INFO.INFO-DM]Computer Science [cs]/Discrete Mathematics [cs.DM] ,16. Peace & justice ,01 natural sciences ,Combinatorics ,Closure system ,Colored ,Distributive property ,010201 computation theory & mathematics ,Lattice (order) ,Discrete Mathematics and Combinatorics ,0101 mathematics ,Mathematics - Abstract
International audience; This paper proposes a representation theory for any finite lattice via set-colored posets, in the spirit of Birkhoff for distributive lattices. The notion of colored posets was introduced in Nourine (2000) [34] and the generalization to set-colored posets was given in Nourine (2000) [35]. In this paper, we give a characterization of set-colored posets for general lattices, and show that set-colored posets capture the order induced by join-irreducible elements of a lattice as Birkhoff’s representation does for distributive lattices. We also give a classification for some lattices according to the coloring property of their set-colored representation including upper locally distributive, upper locally distributive, meet-extremal and semidistributive lattices.
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- 2018
46. Stochastic approximation of quasi-stationary distributions on compact spaces and applications
- Author
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Bertrand Cloez, Michel Benaïm, Fabien Panloup, Institut de Mathématiques (UNINE), Université de Neuchâtel (UNINE), Mathématiques, Informatique et STatistique pour l'Environnement et l'Agronomie (MISTEA), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA), Laboratoire Angevin de Recherche en Mathématiques (LAREMA), Université d'Angers (UA)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), PANORisk, Institut de Mathematiques, and SNF : 200020/149871, 200021/175728
- Subjects
Statistics and Probability ,reinforced random walks ,random perturba- tions of dynamical systems ,Euler scheme ,Quasi-stationary distributions ,Boundary (topology) ,Markov process ,Stochastic approximation ,01 natural sciences ,Measure (mathematics) ,010104 statistics & probability ,symbols.namesake ,Position (vector) ,stochastic approximation ,spectral gap ,Secondary 34F05 ,FOS: Mathematics ,random perturba-tions of dynamical systems ,Applied mathematics ,0101 mathematics ,60J20 ,Mathematics ,60J60 ,Euler scheme AMS-MSC 65C20 ,Markov chain ,010102 general mathematics ,Probability (math.PR) ,random perturbations of dynamical systems ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Compact space ,34F05 ,symbols ,60J10 ,Spectral gap ,65C20 ,Statistics, Probability and Uncertainty ,extinction rate ,60B12 ,Mathematics - Probability - Abstract
International audience; In the continuity of a recent paper ([6]), dealing with finite Markov chains, this paper proposes and analyzes a recursive algorithm for the approximation of the quasi-stationary distribution of a general Markov chain living on a compact metric space killed in finite time. The idea is to run the process until extinction and then to bring it back to life at a position randomly chosen according to the (possibly weighted) empirical occupation measure of its past positions. General conditions are given ensuring the convergence of this measure to the quasi-stationary distribution of the chain. We then apply this method to the numerical approximation of the quasi-stationary distribution of a diffusion process killed on the boundary of a compact set and to the estimation of the spectral gap of irreducible Markov processes. Finally, the sharpness of the assumptions is illustrated through the study of the algorithm in a non-irreducible setting.
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- 2018
47. Viable trajectories for nonconvex differential inclusions with constant delay
- Author
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Hélène Frankowska, Ihab Haidar, Institut de Mathématiques de Jussieu - Paris Rive Gauche (IMJ-PRG (UMR_7586)), Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire QUARTZ (QUARTZ ), Université Paris 8 Vincennes-Saint-Denis (UP8)-Ecole Nationale Supérieure de l'Electronique et de ses Applications (ENSEA)-SUPMECA - Institut supérieur de mécanique de Paris (SUPMECA)-Ecole Internationale des Sciences du Traitement de l'Information (EISTI), and Université Paris 8 Vincennes-Saint-Denis (UP8)-SUPMECA - Institut supérieur de mécanique de Paris-Ecole Nationale Supérieure de l'Electronique et de ses Applications (ENSEA)-Ecole Internationale des Sciences du Traitement de l'Information (EISTI)
- Subjects
0209 industrial biotechnology ,state constraints ,010102 general mathematics ,Closure (topology) ,02 engineering and technology ,State (functional analysis) ,Extension (predicate logic) ,01 natural sciences ,inward pointing conditions ,020901 industrial engineering & automation ,Differential inclusion ,relaxation ,Control and Systems Engineering ,Applied mathematics ,Relaxation (approximation) ,[MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC] ,0101 mathematics ,Constant (mathematics) ,Mathematics ,Delay differential inclusions - Abstract
International audience; In this paper, we consider a nonconvex differential inclusion with constant delay. We study the existence of viable solutions when the state is constrained to the closure of an open subset of R n. The main contribution is a relaxation result stating that, under some assumptions, each "viable solution" of the convexified inclusion can be approximated by "viable solutions" of the original one. This result is obtained thanks to an extension of the celebrated Filippov's theorem to the case of delay differential inclusions.
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- 2018
48. New model transformations for the stability analysis of time-delay systems
- Author
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Alexandre Seuret, Lucie Baudouin, Mohammed Safi, Équipe Méthodes et Algorithmes en Commande ( LAAS-MAC ), Laboratoire d'analyse et d'architecture des systèmes [Toulouse] ( LAAS ), Institut National Polytechnique [Toulouse] ( INP ) -Institut National des Sciences Appliquées - Toulouse ( INSA Toulouse ), Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut National Polytechnique [Toulouse] ( INP ) -Institut National des Sciences Appliquées - Toulouse ( INSA Toulouse ), Institut National des Sciences Appliquées ( INSA ) -Institut National des Sciences Appliquées ( INSA ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National de la Recherche Scientifique ( CNRS ), Équipe Méthodes et Algorithmes en Commande (LAAS-MAC), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), and Université de Toulouse (UT)
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Lyapunov stability ,0209 industrial biotechnology ,Time-delay systems ,Partial differential equation ,Discretization ,010102 general mathematics ,Stability (learning theory) ,Linear matrix inequalities ,02 engineering and technology ,01 natural sciences ,Projection (linear algebra) ,[SPI.AUTO]Engineering Sciences [physics]/Automatic ,Stability conditions ,Transport equation ,020901 industrial engineering & automation ,Control and Systems Engineering ,Ordinary differential equation ,[ SPI.AUTO ] Engineering Sciences [physics]/Automatic ,Applied mathematics ,Model transformations ,Integral inequalities ,0101 mathematics ,Legendre polynomials ,Mathematics - Abstract
International audience; This paper deals with the stability analysis of time delay systems based on continuous-time approach. The originality of the present paper relies on the construction of several models for a same time-delay systems using the interconnection of an ordinary differential equation and a transport partial differential equation. The stability analysis is then performed using a Lyapunov functional. These models are constructed in order to first reduce potentially the complexity of the resulting stability conditions. Second several models are build in order to be interpreted as a discretization scheme as the one usually used in the Lyapunov functional. The proposed result can be seen as a generalized (N − M) discretization which consists in both a time-discretization of the delay interval into M sub-intervals, and the projection of the state function within each sub-interval on the Legendre polynomials of degree less than N. The efficiency of this novel approach is illustrated on an academic example.
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- 2018
49. On a Wasserstein-type distance between solutions to stochastic differential equations
- Author
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Jocelyne Bion-Nadal, Denis Talay, Centre de Mathématiques Appliquées - Ecole Polytechnique (CMAP), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), TO Simulate and CAlibrate stochastic models (TOSCA), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut Élie Cartan de Lorraine (IECL), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Centre de Mathématiques Appliquées - Ecole Polytechnique ( CMAP ), École polytechnique ( X ) -Centre National de la Recherche Scientifique ( CNRS ), TO Simulate and CAlibrate stochastic models ( TOSCA ), Inria Sophia Antipolis - Méditerranée ( CRISAM ), Institut National de Recherche en Informatique et en Automatique ( Inria ) -Institut National de Recherche en Informatique et en Automatique ( Inria ) -Institut Élie Cartan de Lorraine ( IECL ), Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ), ANR-15-CE05-0024,CAESARS,Contrôle et simulation des systèmes électriques, interaction et robustesse(2015), and Talay, Denis
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Statistics and Probability ,[MATH.MATH-PR] Mathematics [math]/Probability [math.PR] ,Type (model theory) ,01 natural sciences ,Measure (mathematics) ,010104 statistics & probability ,Stochastic differential equation ,Bellman equation ,Applied mathematics ,Wasserstein distance ,0101 mathematics ,Mathematics ,60J60 ,Stochastic control ,Weak solution ,010102 general mathematics ,93E20 ,16. Peace & justice ,Coupling (probability) ,[MATH.MATH-PR]Mathematics [math]/Probability [math.PR] ,Stochastic differential equations ,Probability distribution ,and phrases: Stochastic differential equations ,Statistics, Probability and Uncertainty ,[ MATH.MATH-PR ] Mathematics [math]/Probability [math.PR] - Abstract
For the final version of the paper, seehttps://hal.archives-ouvertes.fr/hal-01943863v1; In this paper we introduce a Wasserstein-type distance on the set of the probability distributions of strong solutions to stochastic differential equations. This new distance is defined by restricting the set of possible coupling measures. We prove that it may also be defined by means of the value function of a stochastic control problem whose Hamilton–Jacobi– Bellman equation has a smooth solution, which allows one to deduce a priori estimates or to obtain numerical evaluations. We exhibit an optimal coupling measure and characterizes it as a weak solution to an explicit stochastic differential equation, and we finally describe procedures to approximate this optimal coupling measure. A notable application concerns the following modeling issue: given an exact diffusion model, how to select a simplified diffusion model within a class of admissible models under the constraint that the probability distribution of the exact model is preserved as much as possible?
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- 2018
50. Metamorphoses of functional shapes in Sobolev spaces
- Author
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Alain Trouvé, Nicolas Charon, Benjamin Charlier, Center for Imaging Science (CIS), Johns Hopkins University (JHU), Institut Montpelliérain Alexander Grothendieck (IMAG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre de Mathématiques et de Leurs Applications (CMLA), and École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS)
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Mathematics - Differential Geometry ,Pure mathematics ,Geodesic ,Scalar (mathematics) ,02 engineering and technology ,01 natural sciences ,FOS: Mathematics ,0202 electrical engineering, electronic engineering, information engineering ,Polygon mesh ,0101 mathematics ,Mathematics - Optimization and Control ,49M25, 49Q20, 58B32, 58E50, 68U05, 68U10 ,Mathematics ,Conservation law ,Applied Mathematics ,Numerical analysis ,010102 general mathematics ,Optimal control ,Finite element method ,Sobolev space ,Computational Mathematics ,Differential Geometry (math.DG) ,Computational Theory and Mathematics ,Optimization and Control (math.OC) ,[MATH.MATH-DG]Mathematics [math]/Differential Geometry [math.DG] ,020201 artificial intelligence & image processing ,[MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC] ,Analysis - Abstract
In this paper, we describe in detail a model of geometric-functional variability between fshapes. These objects were introduced for the first time by the authors in [Charlier et al. 2015] and are basically the combination of classical deformable manifolds with additional scalar signal map. Building on the aforementioned work, this paper's contributions are several. We first extend the original $L^2$ model in order to represent signals of higher regularity on their geometrical support with more regular Hilbert norms (typically Sobolev). We describe the bundle structure of such fshape spaces with their adequate geodesic distances, encompassing in one common framework usual shape comparison and image metamorphoses. We then propose a formulation of matching between any two fshapes from the optimal control perspective, study existence of optimal controls and derive Hamiltonian equations and conservation laws describing the dynamics of geodesics. Secondly, we tackle the discrete counterpart of these problems and equations through appropriate finite elements interpolation schemes on triangular meshes. At last, we show a few results of metamorphosis matchings on synthetic and several real data examples in order to highlight the key specificities of the approach., 46 pages, 12 figures
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- 2018
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