ON A SUPER POLYHARMONIC PROPERTY OF A HIGHER-ORDER FRACTIONAL LAPLACIAN

Let 0<α<2,p≥1,m∈ℕ_(+).Consider the positive solution u of the PDE(-△)^(α/2+m)u(x)=u^(p)(x) in R^(n).(0.1) In[1](Transactions of the American Mathematical Society,2021),Cao,Dai and Qin showed that,under the condition u∈Lα,(0.1)possesses a super polyharmonic property (-△)^(k+α/2)u≥0 for k=0,1,⋯,m−1.In this paper,we show another kind of super polyharmonic property(−Δ)^(k)u>0 for k=1,⋯,m−1,under the conditions and(−Δ)^(m)u≥0.Both kinds of super polyharmonic properties can lead to an equivalence between(0.1)and the integral equation u(x)=∫_(R^(n))u^(p)(y)/|x-y|^(n-2m-α)dy.One can classify solutions to(0.1)following the work of[2]and[3]by Chen,Li,Ou.

ON SOME BOUNDARY VALUE PROBLEMS FOR NONHOMOGENOUS POLYHARMONIC EQUATION WITH BOUNDARY OPERATORS OF FRACTIONAL ORDER

In the paper we study questions about solvability of some boundary value prob- lems for a non-homogenous poly-harmonic equation. As a boundary operator we consider differentiation operator of fractional order in Miller-Ross sense. The considered problem is a generalization of well-known Dirichlet and Neumann problems.

COMBINED EFFECTS IN A SEMILINEAR POLYHARMONIC PROBLEM IN THE UNIT BALL

Let m be a positive integer and B be the unit ball of Rn （n≥2）. We investigate the existence, uniqueness and the asymptotic behavior of a positive continuous solution to the following semilinear polyharmonic boundary value problem （-△）mu=a1（x）uα1＋a2（x）uα2 , lim｜x｜→1 u（x） （1-｜x｜）m-1 =0, where α1,α2∈（-1, 1） and a1, a2 are two nonnegative measurable functions on B satisfying some appropriate assumptions related to Karamata regular variation theory.

MULTIPLE NONTRIVIAL SOLUTIONS FOR A CLASS OF SEMILINEAR POLYHARMONIC EQUATIONS

In this paper, we are concerned with the following problem：{（-△）ku=λf（x）｜u｜q-2u＋g（x）｜u｜k＊-2u, x∈Ω, u∈H k0 （Ω）, where Ωis a bounded domain in RN with N ≥2k＋1, 1〈q〈2,λ〉0, f, g are continuous functions on Ω which are somewhere positive but which may change sign on Ω. k＊ = N2/N-2k is the critical Sobolev exponent. By extracting the Palais-Smale sequence in the Nehari manifold, the existence of multiple nontrivial solutions to this equation is verified.

Existence of Solutions to a Class of Navier Boundary Value Problem Involving the Polyharmonic

This paper is devoted to the following high order elliptic problems under the Navier boundary condition: ?Without assuming the standard subcritical polynomial growth condition ensuring the compactness of a bounded (P.S.) sequence, we show that the Navier boundary value problem has at least a weak nontrivial solution for all &#955;&#62;0?by using mountain pass theorem.

<i>L^p</i>Polyharmonic Dirichlet Problems in the Upper Half Plane

In this article, a class of Dirichlet problem with Lp boundary data for poly-harmonic function in the upper half plane is mainly investigated. By introducing a sequence of kernel functions called higher order Poisson kernels and a hierarchy of integral operators called higher order Pompeiu operators, we obtain a main result on integral representation solution as well as the uniqueness of the polyharmonic Dirichlet problem under a certain estimate.

EXISTENCE OF POSITIVE ENTIRE SOLUTIONS FOR POLYHARMONIC EQUATIONS AND SYSTEMS

In this paper, the existence results of positive entire solutions for supercritical polyharmonic equations and system are given.

PRECISE VALUES OF THE BLOCH CONSTANTS OF CERTAIN LOG-p-HARMONIC MAPPINGS

The aim of this article is twofold.One aim is to establish the precise forms of Landau-Bloch type theorems for certain polyharmonic mappings in the unit disk by applying a geometric method.The other is to obtain the precise values of Bloch constants for certain log-p-harmonic mappings.These results improve upon the corresponding results given in Bai et al.(Complex Anal.Oper.Theory,13(2):321-340,2019).

Mean-Value Theorems for Harmonic Functions on the Cube in R^<i>n</i>

Let be a hypercube in Rn. We prove theorems concerning mean-values of harmonic and polyharmonic functions on In(r), which can be considered as natural analogues of the famous Gauss surface and volume mean-value formulas for harmonic functions on the ball in and their extensions for polyharmonic functions. We also discuss an application of these formulas—the problem of best canonical one-sided L1-approximation by harmonic functions on In(r).

Effective Solution of Riemann Problem for Fifth Order Improperly Elliptic Equation on a Rectangle

In this paper we present a numerical method for solving Riemann type problem for the fifth order improperly elliptic equation in complex plane .We reduce this problem to the boundary value problems for properly elliptic equations, and then solve those problems by the grid methods.

A new proof of L^p estimates for the parabolic polyharmonic equations

In this paper we obtain local Lp estimates for the parabolic polyharmonic equations by a straightforward approach.

Measure Estimates of Nodal Sets of Polyharmonic Functions

This paper deals with the function u which satisfies△k_u = 0, where k≥2 is an integer. Such a function u is called a polyharmonic function. The author gives an upper bound of the measure of the nodal set of u, and shows some growth property of u.

Higher order Poisson kernels and L^p polyharmonic boundary value problems in Lipschitz domains

In this article, we introduce higher order conjugate Poisson and Poisson kernels, which are higher order analogues of the classical conjugate Poisson and Poisson kernels, as well as the polyharmonic fundamental solutions, and define multi-layer potentials in terms of the Poisson field and the polyharmonic fundamental solutions, in which the former is formed by the higher order conjugate Poisson and the Poisson kernels. Then by the multi-layer potentials, we solve three classes of boundary value problems(i.e., Dirichlet, Neumann and regularity problems) with L^p boundary data for polyharmonic equations in Lipschitz domains and give integral representation(or potential) solutions of these problems.

Weighted polyharmonic equation with Navier boundary conditions in a half space

We study positive solutions of the following polyharmonic equation with Hardy weights associated to Navier boundary conditions on a half space：where rn is any positive integer satisfying 0 〈 2m 〈 n. We first prove that the positive solutions of （0.1） are super polyharmonic, i.e.,where x＊ = （x1,... ,Xn-1, --Xn） is the reflection of the point x about the plane Rn-1. Then, we use the method of moving planes in integral forms to derive rotational symmetry and monotonicity for the positive solution of （0.3）, in which α can be any real number between 0 and n. By some Pohozaev type identities in integral forms, we prove a Liouville type theorem--the non-existence of positive solutions for （0.1）.

Two-Level Additive Schwarz Methods Using Rough Polyharmonic Splines-Based Coarse Spaces

This paper introduces a domain decomposition preconditioner for elliptic equations with rough coefficients. The coarse space of the domain decomposition method is constructed via the so-called rough polyharmonic splines （RPS for short）. As an approximation space of the eUiptic problem, RPS is known to recover the quasi-optimal convergence rate and attain the quasi-optimal localization property. The authors lay out the formulation of the RPS based domain decomposition preconditioner, and numerically verify the performance boost of this method through several examples.

Polyharmonic Boundary Value Problem in a Sector

In this article, a polyharmonic Neumann function in a sector with angle π n （n N） is studied by convolution. Especially, the outward normal derivatives at three corner points are defined properly. We give the recursive expressions for the polyharmonic Neumann function, obtaining the solution and the condition of solvability for the related polyharmonic Neumann problem.

A Family of Methods of the DG-Morley Type for Polyharmonic Equations

Discontinuous Galerkin methods as a solution technique of second order elliptic problems,have been increasingly exploited by several authors in the past ten years.It is generally claimed the alledged attractive geometrical flexibility of these methods,although they involve considerable increase of computational effort,as compared to continuous methods.This work is aimed at proposing a combination of DGM and non-conforming finite element methods to solve elliptic m-harmonic equations in a bounded domain of R^(n),for n=2 or n=3,with m≥n+1,as a valid and reasonable alternative to classical finite elements,or even to boundary element methods.

NONTRIVIAL SOLUTIONS FOR A POLYHARMONIC EQUATION WITH SINGULAR TERM

The existence of nontrivial solutions for a polyharmonic equation with singular term is proved by Mountain Pass Lemma and Sobolev-Hardy inequality.

APPROXIMATION OF SMOOTH FUNCTIONSBY POLYHARMONIC CARDINAL SPLINESIN L_p(R^n) SPACE

The remainders and the convergence of cardinal polyharmonic spline interpolation are studied, and the asymptotic behavior of the best approximation by polyharmonic spline and the average K-width of some class of smooth functions defined on the Euclidean space Rn are determined.

OPTIMAL CONTROL FOR MULTISCALE ELLIPTIC EQUATIONS WITH ROUGH COEFFICIENTS

This paper concerns the convex optimal control problem governed by multiscale elliptic equations with arbitrarily rough L∞coefficients,which has not only complex coupling between nonseparable scales and nonlinearity,but also important applications in composite materials and geophysics.We use one of the recently developed numerical homogenization techniques,the so-called Rough Polyharmonic Splines(RPS)and its generalization(GRPS)for the efficient resolution of the elliptic operator on the coarse scale.Those methods have optimal convergence rate which do not rely on the regularity of the coefficients nor the concepts of scale-separation or periodicity.As the iterative solution of the nonlinearly coupled OCP-OPT formulation for the optimal control problem requires solving the corresponding(state and co-state)multiscale elliptic equations many times with different right hand sides,numerical homogenization approach only requires one-time pre-computation on the fine scale and the following iterations can be done with computational cost proportional to coarse degrees of freedom.Numerical experiments are presented to validate the theoretical analysis.