Conformally Invariant Elliptic Liouville Equation and Its Symmetry-Preserving Discretization

The symmetry algebra of the real elliptic Liouville equation is an infinite-dimensional loop algebra with the simple Lie algebra o(3, 1) as its maximal finite-dimensional subalgebra. The entire algebra generates the conformal group of the Euclidean plane E₂. This infinite-dimensional algebra distinguishes the elliptic Liouville equation from the hyperbolic one with its symmetry algebra that is the direct sum of two Virasoro algebras. Following a previously developed discretization procedure, we present a difference scheme that is invariant under the group O(3, 1) and has the elliptic Liouville equation in polar coordinates as its continuous limit. The lattice is a solution of an equation invariant under O(3, 1) and is itself invariant under a subgroup of O(3, 1), namely, the O(2) rotations of the Euclidean plane.     

Boundary Value Problems for the Elliptic Sine-Gordon Equation in a Semi-strip

We study boundary value problems posed in a semistrip for the elliptic sine-Gordon equation, which is the paradigm of an elliptic integrable PDE in two variables. We use the method introduced by one of the authors, which provides a substantial generalization of the inverse scattering transform and can be used for the analysis of boundary as opposed to initial-value problems. We first express the solution in terms of a 2×2 matrix Riemann–Hilbert problem whose “jump matrix” depends on both the Dirichlet and the Neumann boundary values. For a well posed problem one of these boundary values is an unknown function. This unknown function is characterised in terms of the so-called global relation, but in general this characterisation is nonlinear. We then concentrate on the case that the prescribed boundary conditions are zero along the unbounded sides of a semistrip and constant along the bounded side. This corresponds to a case of the so-called linearisable boundary conditions, however, a major difficulty for this problem is the existence of non-integrable singularities of the function q _y at the two corners of the semistrip; these singularities are generated by the discontinuities of the boundary condition at these corners. Motivated by the recent solution of the analogous problem for the modified Helmholtz equation, we introduce an appropriate regularisation which overcomes this difficulty. Furthermore, by mapping the basic Riemann–Hilbert problem to an equivalent modified Riemann–Hilbert problem, we show that the solution can be expressed in terms of a 2×2 matrix Riemann–Hilbert problem whose “jump matrix” depends explicitly on the width of the semistrip L, on the constant value d of the solution along the bounded side, and on the residues at the given poles of a certain spectral function denoted by h(λ). The determination of the function h remains open.     

拟线性椭圆型方程奇摄动边值问题

本文讨论了拟线性椭圆型方程奇摄动Robin边值问题。在适当的条件下，利用不动点定理，研究了边值问题解的存在唯一性及其渐近性态。     

The Singularly Perturbed Boundary Value Problems for Semilinear Elliptic Equation

The singularly perturbed boundary value problems for the semilinear elliptic equation are considered. Under suitable conditions and by using the fixed point theorem, the existence, uniqueness and asymptotic behavior of solution for the boundary value problems are studied.     

The Singularly Perturbed Boundary Value Problems for Semilinear Elliptic Equation

The singularly perturbed boundary value problems for the semilinear elliptic equation are considered. Under suitable conditions and by using the fixed point theorem, the existence, uniqueness and asymptotic behavior of solution for the boundary value problems are studied.     

Poisson Kernel for a Degenerate Elliptic Equation and Application to Boundary Value Problems

In this paper we consider the Dirichlet problem to a degenerate elliptic equation in a domain whose interior contains a degenerate surface. By means of the method of expansion of Poisson kernel and applying the properties of special functions, we obtain the twice continuously differentiable solution of the problem on the entire space including infinity.     

Self-Similar Solutions of a Convection Diffusion Equation And Related Semilinear Elliptic Problems

We show that for each M>o, and locally Lipschitz function the elliptic equation: in R^N has a positive and exponentially decaying solution with If Ψ is the solution is unique and strictly positive, and if Ψ is the solution is also . Because of the nonvariational nature of the elliptic problem, we use a topological degree argument. The existence of a family of positive self-similar solutions of the parabolic equation in x R^N with follows. They are “source-type” solutions of the convection-diffusion equation above.     

具有转向点的椭圆型方程奇摄动边值问题

本文讨论了具有转向点的奇摄动椭动椭圆型方程边值问题,利用多重尺度法和比较定理,确定了边值问题解的渐近性态。     

一类二阶拟线性椭圆型方程障碍问题的很弱解

本文在一定条件下,运用Hodge分解、Sobolev嵌入定理和Lp中的Minkcwski不等式等,研究二阶拟线性椭圆型方程divA(x,u,u)=0的障碍问题很弱解的性质.     

非线性椭圆方程自由边值问题球对称解的存在性

给出了如下的非线性椭圆方程自由边值问题-Δu=λu+(1+ε)u+p,x∈B Rn,u|Ω=μ,∫Ωnu=-M(1)在C[0,1]中的球对称解的存在性.并得到比上述问题更一般的非线性椭圆方程自由边值问题-Δu=h(u),x∈B Rn,u|Ω=μ,∫Ωun=-M,在C[0,1]中的球对称解的存在性,其中B为Rn中的单位球,p>1,λ>0,μ<0,M>0,ε>0;λ,μ,M,ε均为常数,n为正整数.     

一类半线性椭圆型方程奇摄动广义边值问题

讨论了一类非线性椭圆方程奇摄动广义边值问题。在适当的条件下,研究了边值问题广义解的存在、唯一性及其渐近性态。     

高阶半线性椭圆型方程奇摄动广义Dirichlet边值问题

本文讨论了半线性椭圆型方程奇摄动广义边值问题,在适当的条件下研究了Dirichlet边值问题广义解的存在唯一性及其渐近性态。     

集对分析对策方程及其应用

应用集对分析理论对社会或军事上相互对立的两方及多方提出了对策方程,并根据对策方程推导出了两方及多方共存的最优条件.     

一类椭圆型方程的多重解

利用极小极大方法获得了一类Dirichlet问题多重解的存在性结果.     

Sublinear Elliptic Equation on Fractal Domains

This paper investigates sub-linear elliptic equations on self-similar fractal sets. With an appropriately defined Laplacian, we obtain the existence of nontrivial solutions of sub-linear elliptic equations
-△u=λu- a（x）｜u｜q-1u-f（x,u）,
with zero boundary Dirichlet conditions. The results are obtained by using Mountain Pass Lemma and Saddle Point Theorem.     

一类四阶半线性椭圆型方程非局部边值问题(英文)

本文研究了一类四阶半线性椭圆型方程奇摄动非局部问题.     

对称锥互补问题

对称锥互补问题是一类均衡优化,包括标准互补问题、二阶锥互补问题和半定互补问题等,近几年,人们借助欧几里德若当代数技术,在对称锥互补问题的研究方面获得了突破性进展并使之逐渐受到重视,本文主要从理论和算法两方面总结和评述这些新成果,同时,列出了相应的重要文献。     

Singular Perturbation Elliptic Boundary-Value Problems in the Case of a Nonisolated Root of the Degenerate Equation

For a singularly perturbed elliptic equation (the Neumann boundary-value problem), we prove a theorem on the passage to the limit for the case in which the degenerate equation has a nonisolated root.__________Translated from Matematicheskie Zametki, vol. 78, no. 1, 2005, pp. 26–36.Original Russian Text Copyright © 2005 by V. F. Butuzov, M. A. Terent’ev.     

Non-coercive Linear Elliptic Problems

We study here some linear elliptic partial differential equations (with Dirichlet, Fourier or mixed boundary conditions), to which convection terms (first order perturbations) are added that entail the loss of the classical coercivity property. We prove the existence, uniqueness and regularity results for the solutions to these problems.