变系数高阶中立型泛函数分方程的振动性与渐近性

考虑变系数高阶中立型泛函微分方程ｄ＾ｎ／ｄｔ＾ｎ（ｘ（ｔ）＋ｐ（ｔ）ｘ（ｔ－τ（ｔ））＋ｍ∑ｉ＝１Ｐｉ（ｔ）ｘ（ｔ－τｉ（ｔ）＝０，在－１＜ｐ（ｔ）≤０情形下解的振动性与渐近性，取消了Ｐｉ（ｔ）≥ｑｉ＞０的限制，改进以往的相应结果，本文结果时高阶泛函方程Ｘ＾（ｎ）（ｔ）＋ｍ∑ｉ＝１ｐｉ（ｔ）ｘ（ｔ－τｉ（ｔ））＝０也是适用的。     

一类抛物型偏泛函微分方程解的强迫振动性

本文研究抛物型偏泛函微分方程γ／γｔ［ｕ－ｍΣｔ－１Ｃｔ（ｔ）ｕ（ｘ，ｔ－τｔ）］＝ａ（ｔ）Δｕ－Ｐ（ｘ，ｔ）ｕ－Ｑ（ｘ，ｔ）Ｇ［ｕ（ｘ，ｐ（ｔ）］＋Ｆ（ｘ，ｔ），（ｘ，ｔ）包含Ｄ×［０，＋∞］解的强近振动性，其中Ｄ为Ｒ＾ｎ中具有逐片光滑边办γＤ的有界区域，ｕ＝ｕ（ｘ，ｔ），Δ是Ｒ＾ｎ中的Ｌａｐｌａｃｅ算子。     

F－半完备环与F－半完备模

本文给出了Ｆ－半备完环的一个刻划：环Ｒ是Ｆ－半完备的当且仅当对任意有限生成左理想Ｒα＿１＋Ｒα＿２＋…＋Ｒα＿ｎ，，其中α＿ｉ∈Ｒ（ｉ＝１，２，…，ｎ）．Ｒ／（Ｒα＿１＋Ｒα＿２＋…＋Ｒα＿ｎ）均有投射覆盖。并把它推广到模上，此外，还得到了投射模的自同态环是半单环的充要条件。     

变系数一阶中立型微分方程的振动性

考虑了微分方程［ｘ（ｔ）－ｐｘ（ｔ－τ）］′＋∑ｎｉ＝１Ｑｉ（ｔ）ｘ（ｔ－τｉ）＝０ｔ≥ｔ０（１）其Ｐ∈Ｒ＋＝［０,∞）,τ,τｉ为正常数,Ｑｉ（ｔ）∈Ｃ（［ｔ０,∞）,Ｒ＋）（ｉ＝１,２,…,ｎ）且∑ｎｉ＝１∫∞ｔ０Ｑｉ（ｔ）ｄｔ＝∞,获得了方程（１）振动的几个充分条件;减弱了文［１］Ｑ（ｔ）为周期系数的条件,推广和改进了文［１］的相应结果,并且有一些结果是新的     

线性常微分方程组解的特征数的估计

复数域上线性系统ｘ＝Ａ（ｔ）ｘ，当Ａ（ｔ）＝（ａｉｊ（ｔ））ｎ×ｎ具有（ｎ，Ｎ，ｒ） 差异性质且ｒｎ时，解的特征数ｊ有估计λｊ－ｌｉｍｔ→∞１ｔ∫ｔｔ０Ｒｅａｊ（τ）ｄτｎ－１ｒ＋１－ｎｌｉｍｔ→∞１ｔ∫ｔｔ０Ａ（τ）ｄτ，ｊ＝１，２，…，ｎ，其中Ａ（ｔ）＝ｍａｘ｛｜ａｉｊ（ｔ）｜：ｉ，ｊ＝１，２，…，ｎ，ｉ≠ｊ．｝     

子集的交叉t－相交定理

设Ｘ为一个ｎ元集合，Ｃｎｋ为Ｘ的所有ｋ元子集全体，若Ａ∈Ａ，Ｂ∈Ｂ有｜Ａ∩Ｂ｜≥ｔ，则称（Ａ，Ｂ）为一个交叉ｔ－相交子集族．本文得到最大交叉ｔ－相交子集族和最大非空交叉２－相交子集族．证明如下两个结论．（１）若（Ａ，Ｂ）为一个交叉ｔ－相交子集族，且ａ≤ｂ及ａ＋ｂ≤ｎ＋ｔ－１，则｜Ａ＋Ｂ｜≤ｍａｘ｛（ｂｎ），（ａｎ）｝，且当（Ａ；Ｂ）＝（φ，Ｃｎｂ）或（Ｃｎａ，φ）时达到上界．（２）若（Ａ，Ｂ）为一个交叉２－相交子集族，且ａ＜ｂ，ａ＋ｂ≤ｎ－１及（ｎ，ａ，ｂ）≠（２ｉ，ｉ－１，ｉ）（ｉ为任意正整数），又Ａ，Ｂ均非空，则｜Ａ＋Ｂ｜≤１＋（ｂｎ）－（ｂ（ｎ－ａ））－ａ（（ｂ－１）（ｎ－ａ））且当（Ａ，Ｂ）＝（｛Ａ｝，Ｃｎｂ－｛Ｂ｜｜Ｂ｜＝ｂ，｜Ａ∩Ｂ｜≤１｝）时达到上界．     

具有交互神经传递时滞的神经网络的稳定性

本文研究了具有交互神经传递时滞的神经网络模型ｘ′ｉ（ｔ）＝－ｂｉｘｉ（ｔ）＋∑ｎｊ＝１ωｉｊｆｊ（ｘｊ（ｔ－τｊ））＋ｐｉ（ｔ＞０；ｉ＝１，２，…，ｎ）平衡点的全局渐近稳定性，并获得了若干充分条件·     

n维时滞Prajneshu生态系统的区间生态稳定

对ｎ维时滞Ｐｒａｊｎｅｓｈｕ＾［１］生态系统ｄｘｉ（ｔ）／ｄｔ＝ｘｉ（ｔ）［ｒｉ＋Σ↑ｎ↓ｊ＝１ａｉｊｌｎｘｊ＋Σ↑ｎ↓ｊ＝１ｂｉｊｌｎｘｊ（ｔ－τｊ）ｉ＝１，２，…，ｎ（１）的区间生态稳定性进行了研究，给出了其区间生态稳定的判别准则。     

一个高阶三点边值问题的可解性

本文考虑以下三点边值问题：ｘ＾（ｎ）＝ｆ（ｔ，ｘ，．．．，ｘ＾ｎ－１）（０≤ｔ≤１），ｘ（０）＝ξ１，ｘ＾（ｉ）（ｃ）＝ξｉ＋１（０≤ｉ≤ｎ－３），ｘ（１）＝ξｎ，其中ｃ∈（０，１）ｇｎ ξｉ∈Ｒ＾ｋ是给定的，利用基于度理论的一定不动点定理，得到了关于以上边值问题的某些存在唯一性结果。     

关于2－因指数群

如果有限群Ｇ的每个极大子群的指数的质因子个数（重因式按重数计算）都小于或等于ｎ，则称Ｇ为ｎ－因指数群。本文用单群分类定理证明了定理设Ｇ为非可解２－因指数群，则Ｃ／Ｓ（Ｇ）同构于下列形式的群之一：Ｎ＿１×Ｎ＿２×…×Ｎ＿ｔ其中Ｎ＿ｉ∈｛Ａ＿５，Ｓ＿５，Ａ＿６，Ｓ＿６，Ａ＿７，Ｓ＿７｝，Ｎ＿１，Ｎ＿２，…，Ｎ＿ｔ两两不同，ｔ＝１，２，３，４，５，６．     

RECENT PROGRESS ON SPHERICAL HARMONIC APPROXIMATION MADE BY BNU RESEARCH GROUP ——In memory of Professor Sun Yongsheng

As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years （2001-2005）. The main topics are： convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.     

On a class of self-similar processes with stationary increments in higher order Wiener chaoses

We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals.     

A REPRESENTATION FORMULA RELATED TO SCHR(O)DINGER OPERATORS

Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.     

On a class of Riemann surfaces

It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary.     

CONTENTS OF VOLUME 30

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Instructions for contributions

正Applied Mathematics-A Journal of Chinese Universities,Series B(Appl.Math.J.Chinese Univ.,Ser.B)is a comprehensive applied mathematics journal jointly sponsored by Zhejiang University,China Society for Industrial and Applied Mathematics,and Springer-Verlag.It is a quarterly journal with     

Journal of Mathematical Research with Applications Guide for Authors

正Journal overview:Journal of Mathematical Research with Applications(JMRA),formerly Journal of Mathematical Research and Exposition(JMRE)created in 1981,one of the transactions of China Society for Industrial and Applied Mathematics,is a home for original research papers of the highest quality in all areas of mathematics with applications.The target audience comprises:pure and applied mathematicians,graduate students in broad fields of sciences and technology,scientists and engineers interested in mathematics.     

Staircase transportation problems with superadditive rewards and cumulative capacities

A cumulative-capacitated transportation problem is studied. The supply nodes and demand nodes are each chains. Shipments from a supply node to a demand node are possible only if the pair lies in a sublattice, or equivalently, in a staircase disjoint union of rectangles, of the product of the two chains. There are (lattice) superadditive upper bounds on the cumulative flows in all leading subrectangles of each rectangle. It is shown that there is a greatest cumulative flow formed by the natural generalization of the South-West Corner Rule that respects cumulative-flow capacities; it has maximum reward when the rewards are (lattice) superadditive; it is integer if the supplies, demands and capacities are integer; and it can be calculated myopically in linear time. The result is specialized to earlier work of Hoeffding (1940), Fréchet (1951), Lorentz (1953), Hoffman (1963) and Barnes and Hoffman (1985). Applications are given to extreme constrained bivariate distributions, optimal distribution with limited one-way product substitution and, generalizing results of Derman and Klein (1958), optimal sales with age-dependent rewards and capacities.To our friend, Philip Wolfe, with admiration and affection, on the occasion of his 65th birthday.Research was supported respectively by the IBM T.J. Watson and IBM Almaden Research Centers and is a minor revision of the IBM Research Report [6].     

Boundedness for commutators of multipliers on Hardy type spaces

In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p（R^n） into the Lebesgue space L^p with p 〈 1.