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Book
Tunneling estimates and approximate controllability for hypoelliptic equations
Authors: ---
ISBN: 9781470451387 Year: 2022 Publisher: Providence, RI : American Mathematical Society,

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Abstract

"This memoir is concerned with quantitative unique continuation estimates for equations involving a "sum of squares" operator L on a compact manifold M assuming: (i) the Chow-Rashevski-Hormander condition ensuring the hypoellipticity of , and (ii) the analyticity of M and the coefficients of . The first result is the tunneling estimate for normalized eigenfunctions of from a nonempty open set , where is the hypoellipticity index of and the eigenvalue. The main result is a stability estimate for solutions to the hypoelliptic wave equation 2 t + L = 0 for T 2 sup (here, dist is the sub- Riemannian distance), the observation of the solution on (0, T) determines the data. The constant involved in the estimate is Ceck where is the typical frequency of the data. We then prove the approximate controllability of the hypoelliptic heat equation (t +L) = 1 in any time, with appropriate (exponential) cost, depending on k. In case k = 2 (Grushin, Heisenberg...), we further show approximate controllability to trajectories with polynomial cost in large time. We also explain how the analyticity assumption can be relaxed, and a boundary M can be added in some situations. Most results turn out to be optimal on a family of Grushin-type operators. The main proof relies on the general strategy to produce quantitative unique continuation estimates, developed by the authors in Laurent-Leautaud (2019)"--


Book
Nilpotent Lie groups: structure and applications to analysis
Author:
ISBN: 3540080554 0387080554 3540375295 Year: 1976 Publisher: Berlin

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Hölder continuity of weak solutions to subelliptic equations with rough coefficients
Authors: ---
ISBN: 0821838261 Year: 2006 Publisher: Providence, R.I. American Mathematical Society


Book
Tunneling Estimates and Approximate Controllability for Hypoelliptic Equations.
Authors: ---
ISBN: 1470470233 Year: 2022 Publisher: Providence : American Mathematical Society,

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Abstract

"This memoir is concerned with quantitative unique continuation estimates for equations involving a "sum of squares" operator L on a compact manifold M assuming: (i) the Chow-Rashevski-Hormander condition ensuring the hypoellipticity of , and (ii) the analyticity of M and the coefficients of . The first result is the tunneling estimate for normalized eigenfunctions of from a nonempty open set , where is the hypoellipticity index of and the eigenvalue. The main result is a stability estimate for solutions to the hypoelliptic wave equation 2 t + L = 0 for T 2 sup (here, dist is the sub- Riemannian distance), the observation of the solution on (0, T) determines the data. The constant involved in the estimate is Ceck where is the typical frequency of the data. We then prove the approximate controllability of the hypoelliptic heat equation (t +L) = 1 in any time, with appropriate (exponential) cost, depending on k. In case k = 2 (Grushin, Heisenberg...), we further show approximate controllability to trajectories with polynomial cost in large time. We also explain how the analyticity assumption can be relaxed, and a boundary M can be added in some situations. Most results turn out to be optimal on a family of Grushin-type operators. The main proof relies on the general strategy to produce quantitative unique continuation estimates, developed by the authors in Laurent-Leautaud (2019)"--


Book
The Hypoelliptic Laplacian and Ray-Singer Metrics. (AM-167)
Authors: ---
ISBN: 128245837X 9786612458378 1400829062 0691137323 0691137315 9781400829064 9780691137315 9780691137322 6612458372 Year: 2008 Publisher: Princeton, NJ

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Abstract

This book presents the analytic foundations to the theory of the hypoelliptic Laplacian. The hypoelliptic Laplacian, a second-order operator acting on the cotangent bundle of a compact manifold, is supposed to interpolate between the classical Laplacian and the geodesic flow. Jean-Michel Bismut and Gilles Lebeau establish the basic functional analytic properties of this operator, which is also studied from the perspective of local index theory and analytic torsion. The book shows that the hypoelliptic Laplacian provides a geometric version of the Fokker-Planck equations. The authors give the proper functional analytic setting in order to study this operator and develop a pseudodifferential calculus, which provides estimates on the hypoelliptic Laplacian's resolvent. When the deformation parameter tends to zero, the hypoelliptic Laplacian converges to the standard Hodge Laplacian of the base by a collapsing argument in which the fibers of the cotangent bundle collapse to a point. For the local index theory, small time asymptotics for the supertrace of the associated heat kernel are obtained. The Ray-Singer analytic torsion of the hypoelliptic Laplacian as well as the associated Ray-Singer metrics on the determinant of the cohomology are studied in an equivariant setting, resulting in a key comparison formula between the elliptic and hypoelliptic analytic torsions.

Keywords

Differential equations, Hypoelliptic. --- Laplacian operator. --- Metric spaces. --- Spaces, Metric --- Operator, Laplacian --- Hypoelliptic differential equations --- Generalized spaces --- Set theory --- Topology --- Differential equations, Partial --- Alexander Grothendieck. --- Analytic function. --- Asymptote. --- Asymptotic expansion. --- Berezin integral. --- Bijection. --- Brownian dynamics. --- Brownian motion. --- Chaos theory. --- Chern class. --- Classical Wiener space. --- Clifford algebra. --- Cohomology. --- Combination. --- Commutator. --- Computation. --- Connection form. --- Coordinate system. --- Cotangent bundle. --- Covariance matrix. --- Curvature tensor. --- Curvature. --- De Rham cohomology. --- Derivative. --- Determinant. --- Differentiable manifold. --- Differential operator. --- Dirac operator. --- Direct proof. --- Eigenform. --- Eigenvalues and eigenvectors. --- Ellipse. --- Embedding. --- Equation. --- Estimation. --- Euclidean space. --- Explicit formula. --- Explicit formulae (L-function). --- Feynman–Kac formula. --- Fiber bundle. --- Fokker–Planck equation. --- Formal power series. --- Fourier series. --- Fourier transform. --- Fredholm determinant. --- Function space. --- Girsanov theorem. --- Ground state. --- Heat kernel. --- Hilbert space. --- Hodge theory. --- Holomorphic function. --- Holomorphic vector bundle. --- Hypoelliptic operator. --- Integration by parts. --- Invertible matrix. --- Logarithm. --- Malliavin calculus. --- Martingale (probability theory). --- Matrix calculus. --- Mellin transform. --- Morse theory. --- Notation. --- Parameter. --- Parametrix. --- Parity (mathematics). --- Polynomial. --- Principal bundle. --- Probabilistic method. --- Projection (linear algebra). --- Rectangle. --- Resolvent set. --- Ricci curvature. --- Riemann–Roch theorem. --- Scientific notation. --- Self-adjoint operator. --- Self-adjoint. --- Sign convention. --- Smoothness. --- Sobolev space. --- Spectral theory. --- Square root. --- Stochastic calculus. --- Stochastic process. --- Summation. --- Supertrace. --- Symmetric space. --- Tangent space. --- Taylor series. --- Theorem. --- Theory. --- Torus. --- Trace class. --- Translational symmetry. --- Transversality (mathematics). --- Uniform convergence. --- Variable (mathematics). --- Vector bundle. --- Vector space. --- Wave equation.

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