二阶微分算子积的自伴性

本文讨论了由正则和奇异的二阶对称微分算式生成的微分算子的积算子的自伴性,得到了积算子为自伴算子时边条件应满足的充分而必要的条件及若干其他结果．     

一类二阶与四阶微分算子积的自伴性

利用矩阵运算及算子的基本理论,讨论了由微分算式L_1=D~((2))+q_1(t)和L_2=D~((4))+q_2(t)其中(D=d/dx,t∈I=[a,b])生成的两个微分算子L_i(i=1,2)积L_1L_2的自伴性问题,并在常型情形下,获得了积算子自伴的充分必要条件.     

一类广义Schrdinger算子的自伴性与本质谱

本文在一类 Ｌｐ位势Ｖ（ｘ）下建立了广义Ｓｃｈｒｏｄｉｎｇｅｒ算子Ｈ＝（－Δ）ｍ＋Ｖ（ｘ）在Ｃ∞０（Ｒｎ）上的本质自伴性，给出了Ｈ的本质谱的分布．     

一类广义Schrdinger算子的自伴性与本质谱

本文在一类 Ｌｐ位势Ｖ（ｘ）下建立了广义Ｓｃｈｒｏｄｉｎｇｅｒ算子Ｈ＝（－Δ）ｍ＋Ｖ（ｘ）在Ｃ∞０（Ｒｎ）上的本质自伴性，给出了Ｈ的本质谱的分布．     

关于J－对称微分算子的J－自伴扩张的若干注记

本文给出了一条解析描述Ｊ－对称微分算子Ｊ－自伴扩张的新途径．我们借助方程Ｔ（ｙ）＝λｏｙ的解，而不是如文［３］利用方程＋（ｙ）＇＝－ｙ的解来描述Ｊ－对称微分算式的所有Ｊ－自伴域在奇异端点的边条件，不过我们假设生成的最小算子具非空正则域．我们对主要定理给出了若干有趣的注，得到了二阶极限圆情形的有趣结果．     

关于J－对称微分算子的J－自伴扩张的若干注记

本文给出了一条解析描述Ｊ－对称微分算子Ｊ－自伴扩张的新途径．我们借助方程Ｔ（ｙ）＝λｏｙ的解，而不是如文［３］利用方程＋（ｙ）＇＝－ｙ的解来描述Ｊ－对称微分算式的所有Ｊ－自伴域在奇异端点的边条件，不过我们假设生成的最小算子具非空正则域．我们对主要定理给出了若干有趣的注，得到了二阶极限圆情形的有趣结果．     

奇异向量微分算子的自伴域

本文在向量值函数空间中,推广应用最大算子域的直和分解法,讨论奇异向量微分算子的自伴扩张问题,给出了奇异形式对称向量微分算式一切自伴扩张域的完全描述,概括了[1—4]的相应结果.     

二项自伴向量微分算子的本质谱

首先利用算子比较的方法,研究了二项自伴向量微分算子的本质谱,得到了这类微分算子的本质谱分布范围;然后利用算子分解定理,得到了这类算子谱的离散性的一个充分条件;最后得到了Sturm-Liouville算子和Schr?dinger算子的本质谱范围,以及这两类算子谱的离散性的一个充分条件.     

关于算子─（▽—ia）2＋Ⅴ的性质（Ⅰ）

In this paper,we consider Schrodinger forms (operators) with singular magnetic vectorpotentials ─(▽—ia）²+Ⅴ. We prove that when the negative part V_{_} of electric potentialV satisfies(?) in dependentof V and a=(a₁,a₂,…,a_N)∈L_loc²(R^N)^N, ─(▽—ia）²+Ⅴ has essential self-adjointextension F and it is the only self-adjoint realization of ─(▽—ia）²+Ⅴ. Moreover,We consider the continuity of (a,V) respect to a and V in the sense of strong resolvent.     

一类自伴微分算子谱的离散性

本文研究了２ｎ阶实系数Ｅｕｌｅｒ微分算式生成的对称微分算子,得到了自伴Ｅｕｌｅｒ微分算子的谱是离散的充分必要条件．     

Large Critical Exponents for Some Second Order Uniformly Elliptic Operators

In this paper we investigate the critical exponents of two families of Pucci's extremal operators. The notion of critical exponent that we have chosen for these fully nonlinear operators which are not variational is that of threshold between existence and nonexistence of the solutions for semilinear equations with pure power nonlinearities. Interesting new exponents appear in this context.     

Maximum Principles for Boundary-Degenerate Second Order Linear Elliptic Differential Operators

We prove weak and strong maximum principles, including a Hopf lemma, for C ² subsolutions to equations defined by linear, second-order, linear, elliptic partial differential operators whose principal symbols vanish along a portion of the domain boundary. The boundary regularity property of the C ² subsolutions along this boundary vanishing locus ensures that these maximum principles hold irrespective of the sign of the Fichera function. Boundary conditions need only be prescribed on the complement in the domain boundary of the principal symbol's vanishing locus. We obtain uniqueness and a priori maximum principle estimates for C ² solutions to boundary value and obstacle problems defined by these boundary-degenerate elliptic operators with partial Dirichlet or Neumann boundary conditions. We also prove weak maximum principles and uniqueness for W ^{1, 2} solutions to the corresponding variational equations and inequalities defined with the aide of weighted Sobolev spaces. The domain is allowed to be unbounded when the operator coefficients and solutions obey certain growth conditions.     

Spectral Properties of Second Order Differential Operators on Two-step Nilpotent Lie Groups

In this paper, spectral properties of certain left invariant differential operators on two-step nilpotent Lie groups are completely described by using the theory of unitary irreducible representations and the Plancherel formulae on nilpotent Lie groups.     

Sampling Integrodifferential Transforms Arising from Second Order Differential Operators

We give sampling theorems associated with boundary value problems whose differential equations are of the form M(y) = λS(y), where M and S are differential expressions of the second and first order respectively and the eigenvalue parameter may appear in the boundary conditions. The class of the sampled functions is not a class of integral transforms as is the case in the classical sampling theory, but it is a class of integrodifferential transforms. We use solutions of the problem as well as Green's function to derive two sampling theorems.     

Accretivity of the General Second Order Linear Differential Operator

For the general second order linear differential operator ■ with complex-valued distributional coefficients a_(jk), b_j, and c in an open set Ω ? R~n(n ≥ 1), we present conditions which ensure that-L~0 is accretive, i.e., Re-L_0φ, φ ≥ 0 for all φ∈ C_0~∞(Ω).     

一类具非线性二阶导数项的Schr dinger方程整体解存在的最佳条件

本文讨论一类具非线性二阶导数项的Schr(?)dinger方程,它在物理上描述了上混合振荡传播．根据基态的变分特征,运用势井方法和凹方法,我们获得了其初值问题整体解存在的一个最佳条件,另外还证明了当初值多小时,初值问题的整体解存在．     

Superparabolic Functions Related to Second Order Hypoelliptic Operators

In this paper, we consider a wide class of second order hypoelliptic partial differential operators with nonnegative characteristic form. We prove a monotone smoothing theorem and a representation formula for superparabolic functions.     

一类Schr?dinger算子的连续谱测度

考虑ｌ²（Ｚ）上的离散Ｓｃｈｒ?ｄｉｎｇｅｒ算子，其势Ｖ_n是一个由ｋ＋１个符号｛０，１，２，…，ｋ｝构成的序列．证明了它具有纯连续谱．     

A Note on the Oscillation of Second Order Differential Equations

We give a sufficient condition for the oscillation of linear homogeneous second order differential equation y + p(x)y + q(x)y = 0, where and is positive real number.