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The successive approximation method for the Dirichlet problem in a planar domain

Dagmar Medková — 2008

Applicationes Mathematicae

The Dirichlet problem for the Laplace equation for a planar domain with piecewise-smooth boundary is studied using the indirect integral equation method. The domain is bounded or unbounded. It is not supposed that the boundary is connected. The boundary conditions are continuous or p-integrable functions. It is proved that a solution of the corresponding integral equation can be obtained using the successive approximation method.

Conditions ensuring T(Y) ⊂ Y.

Dagmar Medková — 2005

Extracta Mathematicae

The following theorem is the main result of the paper: Let X be a complex Banach space and T belong to L(X). Suppose that 0 lies at the unbounded component of the set of those l such that lI - T is a Fredholm operator. Let Y be a dense subspace of the dual space X' and S be a closed operator from Y to X such that T'(Y) is contained in Y and TSy = ST'y for every y belonging to Y. Then for every vector x belonging to X', T'x belongs to Y if and only if x belongs to Y.

Solution of the Neumann problem for the Laplace equation

Dagmar Medková — 1998

Czechoslovak Mathematical Journal

For fairly general open sets it is shown that we can express a solution of the Neumann problem for the Laplace equation in the form of a single layer potential of a signed measure which is given by a concrete series. If the open set is simply connected and bounded then the solution of the Dirichlet problem is the double layer potential with a density given by a similar series.

The third boundary value problem in potential theory for domains with a piecewise smooth boundary

Dagmar Medková — 1997

Czechoslovak Mathematical Journal

The paper investigates the third boundary value problem u n + λ u = μ for the Laplace equation by the means of the potential theory. The solution is sought in the form of the Newtonian potential (1), (2), where ν is the unknown signed measure on the boundary. The boundary condition (4) is weakly characterized by a signed measure T ν . Denote by T ν T ν the corresponding operator on the space of signed measures on the boundary of the investigated domain G . If there is α 0 such that the essential spectral radius of ( α I - T ) is...

Solution of the Dirichlet problem for the Laplace equation

Dagmar Medková — 1999

Applications of Mathematics

For open sets with a piecewise smooth boundary it is shown that a solution of the Dirichlet problem for the Laplace equation can be expressed in the form of the sum of the single layer potential and the double layer potential with the same density, where this density is given by a concrete series.

On essential norm of the Neumann operator

Dagmar Medková — 1992

Mathematica Bohemica

One of the classical methods of solving the Dirichlet problem and the Neumann problem in 𝐑 m is the method of integral equations. If we wish to use the Fredholm-Radon theory to solve the problem, it is useful to estimate the essential norm of the Neumann operator with respect to a norm on the space of continuous functions on the boundary of the domain investigated, where this norm is equivalent to the maximum norm. It is shown in the paper that under a deformation of the domain investigated by a diffeomorphism,...

The Neumann problem for the Laplace equation on general domains

Dagmar Medková — 2007

Czechoslovak Mathematical Journal

The solution of the weak Neumann problem for the Laplace equation with a distribution as a boundary condition is studied on a general open set G in the Euclidean space. It is shown that the solution of the problem is the sum of a constant and the Newtonian potential corresponding to a distribution with finite energy supported on G . If we look for a solution of the problem in this form we get a bounded linear operator. Under mild assumptions on G a necessary and sufficient condition for the solvability...

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