User:DVD206/On 2D Inverse Problems

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On Inverse Problems in 2D


Dedicated to Nicole DeLaittre


About the book [edit | edit source]

Summary [edit | edit source]

The main object of study of this book is the relationship between local and global properties of two-dimensional manifolds (surfaces) and embedded graphs. The dimension of the unknown parameter fits the dimension of the data of the measurements in several important instances of the inverse problems. Also, two-dimensional setting has an additional structure, due to the duality between harmonic functions on embedded graphs and manifolds and the connection to special matrices. The context of the inverse problems provides a unified point of view on the work of many great mathematicians. Some of the problems simplify significantly in the graph theoretical setting, but their solutions nevertheless convey the main ideas of the solutions for their continuous analogs. These are some of the main motivations for writing this book. Even though there are references to many mathematical areas in this book, it is practically self-contained, and is intended for the use by a wide audience of people interested in the subject.

Basic definitions and background[edit | edit source]

We will start with definitions and overview of the main mathematical objects that are involved in the inverse problems of our interest. These include the domains of definitions of the functions and operators, the boundary and spectral data and interpolation/extrapolation and restriction techniques.

Graphs and manifolds [edit | edit source]

Harmonic functions[edit | edit source]

On random processes [edit | edit source]

Special matrices and determinants [edit | edit source]

Electrical networks[edit | edit source]

The inverse problems [edit | edit source]

Rectangular directed layered grid

Rectangular grids and gluing graphs

Ordinary differential equations (ODEs)

Applications to classical problems [edit | edit source]

On the inverse problem of Calderon [edit | edit source]

"Can One Hear the Shape of a Drum?" [edit | edit source]

On inhomogeneous string of Krein[edit | edit source]

Transformations of embedded graphs [edit | edit source]

The rules for replacing conductors in series or parallel connection by a single electrically equivalent conductor follow from the equivalence of the Y-Δ or star-mesh transforms.

Y-Δ and star-mesh transforms[edit | edit source]

Medial graphs [edit | edit source]

Dual graphs and harmonic conjugates[edit | edit source]

Determining genus of a graph[edit | edit source]

Hamilton paths in graphs[edit | edit source]

The new spectral theorem [edit | edit source]

The layered case [edit | edit source]

Fourier coordinates [edit | edit source]

Stieltjes continued fractions [edit | edit source]

Blaschke products[edit | edit source]

Let a_i be a set of n points in the complex unit disc. The corresponding Blaschke product is defined as

If the set of points is finite, the function defines the n-to-1 map of the unit disc onto itself,

If the set of points is infinite, the product converges and defines an automorphism of the complex unit disc, given the Blaschke condition

The following fact will be useful in our calculations:

Pick-Nevanlinna interpolation [edit | edit source]

Cauchy matrices [edit | edit source]

The Cayley transform provides the link between the Stieltjes continued fractions and Blaschke products and the Pick-Nevanlinna interpolation problem at the unit disc and the half-space.

Solution of the inverse problem [edit | edit source]

Rotation invariant layered networks 
A. Elementary symmetric functions and permutations
B. Continued fractions and interlacing properties of zeros of polynomials
C. Wave-particle duality and identities involving integrals of paths in a graph and its Laplacian eigenvalues
D. Square root and finite-differences


Given the Dirichlet-to-Neumann map of a layered network, find the eigenvalues and the interpolate, calculate the Blaschke product and continued fraction. That gives the conductivities of the layeres.

The square root of the minus Laplacian [edit | edit source]

We will now consider an important special case of the inverse problem

The case of the unit disc [edit | edit source]

Zolotarev problem [edit | edit source]

One more graph example[edit | edit source]

Connections between discrete and continuous models [edit | edit source]

Kernel of Dirichlet-to-Neumann map[edit | edit source]

Riemann mapping theorem[edit | edit source]

Hilbert transform [edit | edit source]

Schrodinger equation [edit | edit source]

Variation diminishing property [edit | edit source]

Spectral properties [edit | edit source]

Notation [edit | edit source]

Acknowledgements [edit | edit source]

The author would like to thank Wiki project for the help in all stages of writing the book.

About the author [edit | edit source]

Bibliography [edit | edit source]

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