The theorems of beth and Craig in abstract model theory II. Compact logics

Various compact logics such as stationary logic, positive logic, logics with various cardinality quantifiers and cofinality quantifiers are studied. Counterexamples to the theorems of Beth and Craig are given. Back and forth arguments are studied for the first two logics, transfer theorems presented for positive logic and a new compactness proof for the confinality quantifiers is given.Supported by United States Binational Science Foundation Grant No. 1110.     

半序度量空间中单调映射的不动点定理及混合单调映射的耦合不动点定理

本文在度量空间中引入半序,证明了半序度量空间中单调增加映射的不动点定理及混合单调映射的耦合不动点定理．     

Free boundary problems in the theory of fluid flow through porous media: Existence and uniqueness theorems

Summary Elliptic free boundary problems in the theory of fluid flow through porous media are studied by a new method, which reduces the problems to variational inequalities: existence and uniqueness theorems are proved. Entrata in Redazione il 3 agosto 1972. Research supported by C.N.R. in the frame of the collaboration between L.A.N. of Pavia and E.R.A. 215 of C.N.R.S. and of Paris University. ? Laboratorio di Analisi Numerica del C.N.R. di Pavia ? and ? Università di Pavia ?. ? Università di Pavia ? and ? G.N.A.F.A. del C.N.R. ?.     

Choquet积分的收敛定理

Murofushi、Sugeno等学者已对关于模糊测度的Choquet积分进行了详细的研究,但关于积分的收敛理论是不够的。本文讨论这一问题,给出Choquet积分的一些收敛定理,包括广义单调收敛定理、Fatou引理等。从中可以看出,Choquet积分与Sugeno模糊积分具有相同的收敛定理。     

Numerical solutions of coupled systems of nonlinear elliptic equations

This article deals with numerical solutions of a general class of coupled nonlinear elliptic equations. Using the method of upper and lower solutions, monotone sequences are constructed for difference schemes which approximate coupled systems of nonlinear elliptic equations. This monotone convergence leads to existence‐uniqueness theorems for solutions to problems with reaction functions of quasi‐monotone nondecreasing, quasi‐monotone nonincreasing and mixed quasi‐monotone types. A monotone domain decomposition algorithm which combines the monotone approach and an iterative domain decomposition method based on the Schwarz alternating, is proposed. An application to a reaction‐diffusion model in chemical engineering is given. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 621–640, 2012     

关于α-凸凹混合单调算子的不动点定理

引入了α-凸凹混合单调算子的概念.借助于集值分析的方法,利用锥理论讨论了这类混合单调算子,得到了若干α-凸凹混合单调算子不动点的存在性和唯一性定理.     

Systems of first order differential inclusions with maximal monotone terms

In this paper, we establish the existence of solutions to systems of first order differential inclusions with maximal monotone terms satisfying the periodic boundary condition. Our proofs rely on the theory of maximal monotone operators, and the Schauder and the Kakutani fixed point theorems. A notion of solution-tube to these problems is introduced. This notion generalizes the notion of upper and lower solutions of first order differential equations.     

Existence and Uniqueness of Fixed Points for Mixed Monotone Operators with Application

In this paper, a class of mixed monotone operators is studied. Some new fixed point theorems are presented by means of partial order theory, and the uniqueness and existence of fixed points are obtained without assuming the operator to be compact or continuous. Our conclusions extend the relevant results. Moreover,as an application of our result, the existence and uniqueness of positive solution for a class of fractional differential equation boundary value problem are proved.     

广义模糊数及其序列的极限

重新定义了广义模糊数,引入了"序"、"运算"及"度量",得到了一些基本性质,并研究了广义模糊数序列的极限及性质,给出了单调收敛、闭区间套等重要定理,使模糊数对应理论得以拓广.     

极大单调映象的满射定理及其应用

The main purpose of this paper is to study the surjectivity theorems for maximal monotone mapping in reflexive Banach spaces by using fixed point theory.We prove some new surjectivity theorems under some conditions and give its application in differential equation.     

混合单调算子的某些不动点定理与锥上的正不动点

给出在半序距离空间以迭代而得到的某些不动点定理的混合单调算子和在锥上某些非零不动点定理。     

Anti-periodic solutions for differential inclusions in Banach spaces and their applications

We deal with anti-periodic problems for differential inclusions with nonmonotone perturbations. The main tools in our study are the maximal monotone property of the derivative operator with anti-periodic conditions and the theory of pseudomonotone perturbations of maximal monotone mappings. We then apply our results to evolution hemivariational inequalities and parabolic equations with nonmonotone discontinuities, which generalize and extend previously known theorems.     

Existence of solutions and existence of optimal solutions. The quasi linear case

By properties of operators of the Brezis type (m), monotone operator theory, and fixed point theorems, the authors prove existence theorems for solutions, and existence theorems for optimal solutions, in problems monitored by nonlinear abstract parabolic type equations. Applications are made to Cauchy-Dirichlet and to Cauchy-Neumann problems, in a cylinder. It is shown that seminormality requirements of previous papers can be dropped. In an alternative approach, controllability results are obtained by a direct application of Kakutani type fixed point theorems.     

THE POSITIVE PERIODIC SOLUTIONS OF PERIODIC RFDEs WITH INFINITE DELAY

This paper is concerned with the periodic retarded functional differential equati-ons(RFDEs) with infinite delay. The sufficient conditions for the existence of noncon-stant positive periodic solutions are established by combining the theory of monotone semiflows generated by RFDEs with infinite delay and the fixed point theorems of solution operators. A nontrivial application of the results obtained here to a well-known nonautonomous Lotka-Volterra system with infinite delay is also presented.     

混合单调算子的两点拉伸型不动点定理

本文首次提出了混合单调算子不动点的两点拉伸型条件.同时,利用锥映象的不动点指数理论建立了一类特殊的两点拉伸型混合单调算子的不动点存在性定理,并将所得结论应用于带有超线性项的积分方程与微分方程上,得到了新的结论.因而在本质上推进了混合单调算子不动点问题的研究.     

Upper semicontinuity of set-valued functions

Various types of upper semcontinuity properties for set-valued functions have been used in the past to obtain closure and lower closure theorems in optimal control theory as well as selection theorems and fixed-point theorems in topology. This paper unifies these various concepts by using semiclosure operators, extended topologies, and lattice theoretic operations and obtains general closure theorems. In addition, analytic criteria are given for this generalized upper semicontinuity. In particular, set-valued functions which are maximal in terms of certain properties (e.g., maximal monotone multifunctions) are shown to be necessarily upper semicontinuous.     

Existence of nonzero solutions for a class of generalized variational inequalities

The existence of nonzero solutions for a class of generalized variational inequalities is studied by topological degree theory for multi-valued mappings in finite dimensional spaces and reflexive Banach space. One of the mappings concerned here is nonlinear with coercive or monotone and other is set-contractive or upper semi-continuous. Under some suitable assumptions, some existence theorems of nonzero solutions for this generalized variational inequalities are obtained. This work was supported by the Young Talent Foundation of Zhejiang Gongshang University and the Foundation of Department of Education of Zhejiang Province No. 20070628.     

证券市场信息传播的数学模型研究

根据信息的传播理论,从信息传播的实际出发,以股票市场中内部信息的传播如何影响股价的波动及交易量的变化为主要研究内容,从全新的角度建立数学模型来描述了信息自身的传播过程,预测传播的高峰时刻,分析其过程中股票交易量的变化情况.给出了该模型的两个定理.定理1说明:传播信息的投资者的人数先单调增加,然后单调减少并趋于零;定理2表明总有一部分人在信息公布之前无法得知内部消息.从模型得出的两个定理与信息传播的真实形式相符合,说明了模型的准确性.     

一类反向混合单调算子新不动点定理的推广

利用锥理论和非对称迭代方法,讨论了一类反向混合单调算子的不动点的存在唯一性,得到了若干不具有连续性和紧性条件的有关反向混合单调算子的新不动点定理,所得结果是某些已有结果的本质改进和推广.     

Monotone method and convergence acceleration for finite-difference solutions of parabolic problems with time delays

In this article we study a finite-difference system, which is a discrete version of a class of nonlinear reaction-diffusion systems with time delays. Existence-comparison and uniqueness theorem are first established for the discretized problem by the method of upper and lower solutions. A monotone iterative scheme is also developed for the solution of the finite-difference system. Under a convergence acceleration scheme, it is shown that the monotone sequences converge quadratically to the solution of the finite-difference system. At last, numerical results on some model problems are demonstrated to substantiate our theorems. © 1995 John Wiley & Sons, Inc.