列压缩算子的不动点定理及其应用

本文在无连续性及紧性的假设情况下,讨论了u0-凹的列压缩算子及一类混合单调算子的不动点定理,并给出了在积分方程中的应用.     

φ凹(-φ凸)算子不动点定理及其应用

讨论了φ凹(-φ凸)算子,得到了φ凹增(-φ凸减)算子不动点存在唯一性结果,并且给出了收敛到该不动点的迭代序列.该结果去掉了以往文献中的φ→0(t→0~+)这一条件,从而改进和推广了相关结果.作为应用,给出了一类的Sturm-Liouville边值问题的正解的存在唯一性结果.     

凹凸算子和与积的不动点及固有元

本文获得线性半序空间正锥上α凹与-α凸算子的和与积存在不动点的充分条件,并给出了迭代程序与误差估计.还讨论了固有值与固有元之间的关系.     

一类混合单调算子的不动点的存在唯一性

该文引入了φ凹-(-ψ)凸算子,统一处理了一类具有某种凹凸性的混合单调算子,在非紧非连续条件下,得到了算子的不动点的存在唯一性和迭代收敛性,进而得到了具有a凹-Guo凸,凹-Guo凸,μ₀凹-凸,μ₀凹-(-a)凸或α₁凹-(-α₂)凸等性质的混合单调算子的新不动点定理。     

一类带有分数阶微分边值条件的分数阶微分方程在奇异的和非奇异的情况下的唯一正解(英文)

本文研究下列分数阶微分方程在奇异和非奇异的情况下的边值问题{D_0~α+u(t)+f(t,u(t))=0,t∈(0,1),3α≤4,u(0)=0,D_(0+)~(α-1)u(0)=0,D_(0+)~(α-2)u(0)=0,D_(0+)~(a-3)u(1)=0.通过计算,得到分数阶格林公式.利用半序集上的不动点定理和u_0凸算子不动点定理,得到上述问题存在唯一正解.     

一类边值问题正解的存在唯一性

利用u0凹算子的不动点理论给出了一类四阶边值问题存在唯一正解的条件.     

一类凹与凸算子的推广

运用锥的性质以及单调迭代技巧给出了一类广义凹算子与凸算子正不动点的存在唯一性,并讨论了算子特征值方程的性质.作为应用,利用所获结果研究了一类积分方程正解的存在唯一性.     

φ凹(-Ψ)凸混合单调算子不动点存在惟一性及其应用

该文引入了φ凹-(—ψ)凸算子,统一处理了一类具有某种凹凸性的混合单调算子,在非紧非连续的条件下,利用单凋叠代技巧证明了不动点的存在惟一,进而得到了具有α凹-凸、凹-(—α)凸、α凹-Guo凸、凹-Guo凸、e凹-Guo凸、e凹-凸、e凹-(—α)凸以及α_1凹-(—α_2)凸等性质的混合单调算子的新不动点定理,并将所获结果应用于Hammerstein非线性积分方程。     

几类随机序关系关于随机最大与随机最小的反向封闭性质

研究了右扩展序、TTT序、单调增凸序和单调增凹序分别关于随机最大与随机最小的反向封闭性质, 并讨论了相关年龄概念关于随机最大与随机最小的反向封闭性质.     

Ф凹（-φ）凸混合单调算子不动点存在惟一性及其应用

该文引入了Ф凹（-φ）凸算子，统一处理了一类具有某种凹凸性的混合单调算子，在非紧非连续的条件下，利用单调叠代技巧证明了不动点的存在惟一，进而得到了具有α凹-凸、凹-（-α）凸、α凹-Guo凸、凹-Guo凸、e凹-Guo凸、e凹-凸、e凹-（-α）凸以及α1凹-（-α）凸等性质的混合单调算子的新不动点定理，并将所获结果应用于Hammerstein非线性积分方程．     

Minimarg and maximarg operators

Two operators on the set ofn-person cooperative games are introduced, the minimarg operator and the maximarg operator. These operators can be seen as dual to each other. Some nice properties of these operators are given, and classes of games for which these operators yield convex (respectively, concave) games are considered. It is shown that, if these operators are applied iteratively on a game, in the limit one will yield a convex game and the other a concave game, and these two games will be dual to each other. Furthermore, it is proved that the convex games are precisely the fixed points of the minimarg operator and that the concave games are precisely the fixed points of the maximarg operator.     

On Concave Operators

We prove that a u0-concave operator can include other concave operators, and derive a sufficient and necessary condition for the existence and uniqueness of the fixed point of a kind of u0-concave operator under a weaker condition.     

A Method for Converting a Class of Univariate Functions into d.c. Functions

D.c. functions are functions that can be expressed as the sum of a concave function and a convex function (or as the difference of two convex functions). In this paper, we extend the class of univariate functions that can be represented as d.c. functions. This expanded class is very broad including a large number of nonlinear and/or nonsmooth univariate functions. In addition, the procedure specifies explicitly the functional and numerical forms of the concave and convex functions that comprise the d.c. representation of the univariate functions. The procedure is illustrated using two numerical examples. Extensions of the conversion procedure for discontinuous univariate functions is also discussed.     

THE PHYSICAL ENTROPY OF SINGLE CONSERVATION LAWS

1.IntroductionAsthesimplestrepresentationofgeneralconservationlaws,thesingleconservationlawswithonespacevariablehavebeenthoroughlydiscussed.Inthecasesthatthefluxfunctionisconvexorconcave,P.D.LaxobtainedageneralexpressionofthesolutionsforCauchyproblems[2];inordertoguaranteetheuniquenessofthesolution,O.A.OlejnikpresentedherfamousE--conditionwhichcanbeappliedtogeneralconservationlawswithonespacevariablel4];TheLax'sconceptsofentropyfunctionsandrelatedinequalityalsocanbeusedinthisspecialcase[3]…     

一类混合单调算子新的不动点定理及其应用

引入了广义Φ凹（-φ）凸算子这一概念,在非紧非连续条件下,得到了混合单调算子的几个新的不动点存在唯一性定理.最后给出了一个应用.     

Sharp norm estimates for a class of integral operators

ABSTRACT

Norm comparison inequalities for two integral operators with radial kernels are established. Sharp norm estimates for operators with monotone and convex/concave kernels are obtained. Integral analogues of Bennett's estimates for summability matrices are given. The exact operator norms with power weights are also obtained for a class of integral operators with radial quasimonotone kernels.     

Fixed point theorems of ? convex −ψ concave mixed monotone operators and applications

In this paper, ? convex −ψ concave mixed monotone operators are introduced and some new existence and uniqueness theorems of fixed points for mixed monotone operators with such convexity concavity are obtained. As an application, we give one example to illustrate our results.     

Discrete Convexity

In the paper, we explain what subsets of the lattice ℤ ⁿ and what functions on the lattice ℤ ⁿ could be called convex. The basis of our theory is the following three main postulates of classical convex analysis: concave functions are closed under sums; they are also closed under convolutions; and the superdifferential of a concave function is nonempty at each point of the domain. Interesting (and even dual) classes of discrete concave functions arise if we require either the existence of superdifferentials and closeness under convolutions or the existence of superdifferentials and closeness under sums. The corresponding classes of convex sets are obtained as the affinity domains of such discretely concave functions. The classes of the first type are closed under (Minkowski) sums, and the classes of the second type are closed under intersections. In both classes, the separation theorem holds true. Unimodular sets play an important role in the classification of such classes. The so-called polymatroidal discretely concave functions, most interesting for applications, are related to the unimodular system . Such functions naturally appear in mathematical economics, in Gelfand-Tzetlin patterns, play an important role for solution of the Horn problem, for describing submodule invariants over discrete valuation rings, and so on. Bibliography: 6 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 312, 2004, pp. 86–93.