| Preface | 6 |
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| Denotations | 10 |
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| Contents | 14 |
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| 1 Basic concepts and examples | 18 |
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| 1.1 On the definition of inverse and ill-posed problems | 18 |
| 1.2 Examples of inverse and ill-posed problems | 26 |
| 2 Ill-posed problems | 39 |
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| 2.1 Well-posed and ill-posed problems | 41 |
| 2.2 On stability in different spaces | 42 |
| 2.3 Quasi-solution. The Ivanov theorems | 45 |
| 2.4 The Lavrentiev method | 48 |
| 2.5 The Tikhonov regularization method | 51 |
| 2.6 Gradient methods | 59 |
| 2.7 An estimate of the convergence rate with respect to the objective functional | 66 |
| 2.8 Conditional stability estimate and strong convergence of gradient methods applied to ill-posed problems | 70 |
| 2.9 The pseudoinverse and the singular value decomposition of an operator | 79 |
| 3 Ill-posed problems of linear algebra | 85 |
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| 3.1 Generalization of the concept of a solution. Pseudo-solutions | 87 |
| 3.2 Regularization method | 89 |
| 3.3 Criteria for choosing the regularization parameter | 94 |
| 3.4 Iterative regularization algorithms | 94 |
| 3.5 Singular value decomposition | 96 |
| 3.6 The singular value decomposition algorithm and the Godunov method | 104 |
| 3.7 The square root method | 108 |
| 3.8 Exercises | 109 |
| 4 Integral equations | 115 |
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| 4.1 Fredholm integral equations of the first kind | 115 |
| 4.2 Regularization of linear Volterra integral equations of the first kind | 121 |
| 4.3 Volterra operator equations with boundedly Lipschitz-continuous kernel | 128 |
| 4.4 Local well-posedness and uniqueness on the whole | 133 |
| 4.5 Well-posedness in a neighborhood of the exact solution | 135 |
| 4.6 Regularization of nonlinear operator equations of the first kind | 139 |
| 5 Integral geometry | 146 |
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| 5.1 The Radon problem | 147 |
| 5.2 Reconstructing a function from its spherical means | 155 |
| 5.3 Determining a function of a single variable from the values of its integrals. The problem of moments | 156 |
| 5.4 Inverse kinematic problem of seismology | 161 |
| 6 Inverse spectral and scattering problems | 171 |
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| 6.1 Direct Sturm-Liouville problem on a finite interval | 173 |
| 6.2 Inverse Sturm-Liouville problems on a finite interval | 180 |
| 6.3 The Gelfand-Levitan method on a finite interval | 183 |
| 6.4 Inverse scattering problems | 189 |
| 6.5 Inverse scattering problems in the time domain | 197 |
| 7 Linear problems for hyperbolic equations | 204 |
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| 7.1 Reconstruction of a function from its spherical means | 204 |
| 7.2 The Cauchy problem for a hyperbolic equation with data on a time-like surface | 207 |
| 7.3 The inverse thermoacoustic problem | 209 |
| 7.4 Linearized multidimensional inverse problem for the wave equation | 210 |
| 8 Linear problems for parabolic equations | 226 |
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| 8.1 On the formulation of inverse problems for parabolic equations and their relationship with the corresponding inverse problems for hyperbolic equations | 226 |
| 8.2 Inverse problem of heat conduction with reverse time (retrospective inverse problem) | 231 |
| 8.3 Inverse boundary-value problems and extension problems | 244 |
| 8.4 Interior problems and problems of determining sources | 245 |
| 9 Linear problems for elliptic equations | 250 |
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| 9.1 The uniqueness theorem and a conditional stability estimate on a plane | 251 |
| 9.2 Formulation of the initial boundary value problem for the Laplace equation in the form of an inverse problem. Reduction to an operator equation | 255 |
| 9.3 Analysis of the direct initial boundary value problem for the Laplace equation | 256 |
| 9.4 The extension problem for an equation with self-adjoint elliptic operator | 261 |
| 10 Inverse coefficient problems for hyperbolic equations | 266 |
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| 10.1 Inverse problems for the equation utt = uxx – q(x)u + F(x,t) | 266 |
| 10.2 Inverse problems of acoustics | 289 |
| 10.3 Inverse problems of electrodynamics | 303 |
| 10.4 Local solvability of multidimensional inverse problems | 311 |
| 10.5 Method of the Neumann to Dirichlet maps in the half-space | 319 |
| 10.6 An approach to inverse problems of acoustics using geodesic lines | 323 |
| 10.7 Two-dimensional analog of the Gelfand-Levitan-Krein equation | 332 |
| 11 Inverse coefficient problems for parabolic and elliptic equations | 336 |
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| 11.1 Formulation of inverse coefficient problems for parabolic equations. Association with those for hyperbolic equations | 336 |
| 11.2 Reducing to spectral inverse problems | 338 |
| 11.3 Uniqueness theorems | 340 |
| 11.4 An overdetermined inverse coefficient problem for the elliptic equation. Uniqueness theorem | 344 |
| 11.5 An inverse problem in a semi-infinite cylinder | 345 |
| Appendix A | 348 |
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| A.1 Spaces | 348 |
| A.2 Operators | 367 |
| A.3 Dual space and adjoint operator | 388 |
| A.4 Elements of differential calculus in Banach spaces | 399 |
| A.5 Functional spaces | 402 |
| A. 6 Equations of mathematical physics | 417 |
| Appendix B | 428 |
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| B.1 Supplementary exercises and control questions | 428 |
| B.2 Supplementary references | 430 |
| Epilogue | 448 |
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| Bibliography | 450 |
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| Index | 474 |