Elliptic Pseudodifferential Equations Research Articles

On Some Elliptic Boundary Value Problems in Conic Domains

A model elliptic pseudodifferential equation in a polyhedral cone is considered, and the situation when some of the parameters of the cone tend to their limiting values is investigated. In Sobolev–Slobodetskii spaces, a solution of the equation in the cone is constructed in the case of a special wave factorization of the elliptic symbol. It is shown that a limit solution of the boundary value problem with an additional integral condition can exist only under additional constraints on the boundary function.

On a general discrete boundary value problem for an elliptic pseudo-differential equation in a quadrant

On a general discrete boundary value problem for an elliptic pseudo-differential equation in a quadrant

Ellipticheskie zadachi i integral'nye uravneniya v prostranstvakh razlichnoy gladkosti po peremennym

We consider a model elliptic pseudodifferential equation and the simplest boundary value problems in a quadrant in a Sobolev–Slobodetsky space of different orders of smoothness in different variables. In the case of a special representation of the symbol, we describe a general solution of the equation and consider the simplest boundary value problem with the Dirichlet and Neumann conditions on the sides of the quadrant. This boundary value problem is reduced to a system of integral equations, which, under additional assumptions about the structure of the symbol, can also be reduced to a system of first-order difference equations

On Certain Operator Families

In this paper, we propose an abstract scheme for the study of special operators and apply this scheme to examining elliptic pseudo-differential operators and related boundary-value problems on manifolds with nonsmooth boundaries. In particular, we consider cases where boundaries may contain conical points, edges of various dimensions, and even peak points. Using the constructions proposed, we present well-posed formulations of boundary-value problems for elliptic pseudo-differential equations on manifolds discussed in Sobolev–Slobodecky spaces.

Conjugation problem for elliptic pseudodifferential equations on the plane

Conjugation problem for elliptic pseudodifferential equations on the plane

On Discrete Solutions for Elliptic Pseudo-Differential Equations

We consider discrete analogue for simplest boundary value problem for elliptic pseudo-differential equation in a half-space with Dirichlet boundary condition in Sobolev–Slobodetskii spaces. Based on the theory of discrete boundary value problems for elliptic pseudo-differential equations we give a comparison between discrete and continuous solutions for certain model boundary value problem.

On Solvability Conditions for a Certain Conjugation Problem

We study a certain conjugation problem for a pair of elliptic pseudo-differential equations with homogeneous symbols inside and outside of a plane sector. The solution is sought in corresponding Sobolev–Slobodetskii spaces. Using the wave factorization concept for elliptic symbols, we derive a general solution of the conjugation problem. Adding some complementary conditions, we obtain a system of linear integral equations. If the symbols are homogeneous, then we can apply the Mellin transform to such a system to reduce it to a system of linear algebraic equations with respect to unknown functions.

О дискретных эллиптических псевдодифференциальных уравнениях

О дискретных эллиптических псевдодифференциальных уравнениях

On Some Multidimensional Limit Boundary Value Problems

We study solvability for a model elliptic pseudo-differential equation with an additional integral condition in Sobolev–Slobodetskii spaces in certain conical domains in Euclidean space. . Using the wave factorization for an elliptic symbol we construct a solution for this boundary value problem and study the behavior of the solution when parameters of cones tend to their extremal values. It was shown that for such a solvability we need certain additional condition besides presented integral condition.

Optimal operator preconditioning for pseudodifferential boundary problems

We propose an operator preconditioner for general elliptic pseudodifferential equations in a domain $\Omega$, where $\Omega$ is either in $\mathbb{R}^n$ or in a Riemannian manifold. For linear systems of equations arising from low-order Galerkin discretizations, we obtain condition numbers that are independent of the mesh size and of the choice of bases for test and trial functions. The basic ingredient is a classical formula by Boggio for the fractional Laplacian, which is extended analytically. In the special case of the weakly and hypersingular operators on a line segment or a screen, our approach gives a unified, independent proof for a series of recent results by Hiptmair, Jerez-Hanckes, N\'{e}d\'{e}lec and Urz\'{u}a-Torres. We also study the increasing relevance of the regularity assumptions on the mesh with the order of the operator. Numerical examples validate our theoretical findings and illustrate the performance of the proposed preconditioner on quasi-uniform, graded and adaptively generated meshes.

Boundary Value Problems for Elliptic Pseudodifferential Equations in a Multidimensional Cone

We consider model boundary value problems for elliptic pseudodifferential equations in multidimensional cones. A result on the unique solvability and representation of solutions of some boundary value problems in suitable Sobolev–Slobodetskii spaces is obtained. A priori estimates of solutions are given.

On Certain 3-Dimensional Limit Boundary Value Problems

The paper is devoted to studying limit behavior for a solution of model elliptic pseudo-differential equation with some integral boundary condition in 4-wedge conical canonical 3D singular domain with two parameters. It is shown that the solution of such boundary value problem can have a limit with respect to endpoint values of the parameters in appropriate Sobolev–Slobodetskii space if the boundary function is a solution of a special functional singular integral equation.

On some pseudo-differential equations and transmutation operators

We describe some operators for solving model elliptic pseudo-differential equations in special canonical domains. It helps us to write a general solution of corresponding pseudo-differential equation in an explicit form. Moreover, knowing a general solution we can choose additional (possibly boundary) conditions to determine uniquely the solution. All considerations we give in Sobolev–Slobodetskii spaces.

On some distributions associated to boundary value problems

We consider an elliptic pseudo-differential equation in a multidimensional cone in Sobolev–Slobodetskii space and describe its general solution for some cases. This description is based on some distributions supported on a conical surface. For certain conical surfaces we describe such distributions. It permits to use such distributions to refine a general solution.

Pseudo-differential equations and conical potentials: 2-dimensional case

We consider two-dimensional elliptic pseudo-differential equation in a plane sector. Using a special representation for an elliptic symbol and the formula for a general solution we study the Dirichlet problem for such equation. This problem was reduced to a system of linear integral equations and then after some transformations to a system of linear algebraic equations. The unique solvability for the Dirichlet problem was proved in Sobolev-Slobodetskii spaces and a priori estimate for the solution is given.

Pseudodifferential Operators and Equations of Variable Order

A new class of elliptic pseudodifferential equations of variable order is considered. Local Sobolev–Slobodetskii spaces are introduced and used to obtain theorems on the continuity of these pseudodifferential operators and describe the Fredholm properties of the corresponding pseudodifferential equations and boundary value problems.

Model Elliptic Boundary-Value Problems for Pseudodifferential Operators in Canonical Nonsmooth Domains

We consider a simplest elliptic pseudodifferential equation in a multi-dimensional cone (multi-dimensional angle) and describe all possible structures of its solutions related to the wave factorization of the elliptic symbol. Depending on the index of wave factorization, we consider various statements of well-posed boundary-value problems. The existence of solutions is studied in Sobolev–Slobodetskii spaces.

Pseudodifferential equations, wave factorization, and related problems

We consider a model elliptic pseudodifferential equation in a special canonical domains of a multidimensional space. Using a special representation for an elliptic symbol, we give the formula for a general solution of such an equation and choose additional conditions under which this boundary value problem has a unique solution in appropriate Sobolev‐Slobodetskii spaces. Also, we introduce some transmutation operators that help us in constructing the solution.

A fast trigonometric collocation method for some elliptic pseudodifferential equations

In this paper, we propose and analyze a fast trigonometric collocation method for a class of periodic elliptic pseudodifferential equations, whose pseudodifferential operators can always be represented as the sum of a principal part and a smoothing operator. We show that the whole matrix representation for the principal part in our discrete linear system can be generated by only computing O(n) entries rather than computing all entries of the matrix, where 2n or 2n+1 is the size of the matrix. The dense matrix for the smoothing operator can be compressed into a sparse matrix with only O(nlogn) nonzero entries. We also prove that our proposed method preserves the optimal convergent order the same as without compression. Some numerical experiments for solving three cases of boundary integral equations are presented to demonstrate its approximate accuracy and computational efficiency, verifying the theoretical estimates.

Global bifurcation of steady gravity water waves with critical layers

We construct families of two-dimensional travelling water waves propagating under the influence of gravity in a flow of constant vorticity over a flat bed, in particular establishing the existence of waves of large amplitude. A Riemann–Hilbert problem approach is used to recast the governing equations as a one-dimensional elliptic pseudodifferential equation with a scalar constraint. The structural properties of this formulation, which arises as the Euler–Lagrange equation of an energy functional, enable us to develop a theory of analytic global bifurcation.