一个不等式的几何证法及推广引申

已知a〉1/3，b〉1/3，ab=2/9，求证a＋b〈1，文[1]、[2]、[3]分别用不同的方法证明此不等式，文[3]对它进行了推广，文[4]对文[3]的推广进行了改进并提出了一个“孪生”不等式．本文首先给出此不等式的一个几何证法，然后利用这一证法对此不等式进行推广引申．     

三角形的一个向量性质再探究

文[1]给出了三角形重心向量的一个性质，并进行了空间拓广．文[2]对三角形内任一点的向量性质进行了探究，并进行了空间拓广．文[3]对文[1]的性质进行再探究，本文类比文[3]对文[2]的性质进行再探究，得到了两个定理，现叙述如下．     

三角形与三棱锥的一个向量性质的逆定理

文[1]、文[2]、文[3]及文[4]对一个三角形重心向量性质进行拓广，文[5]证明了文[1]的逆定理也成立，文[6]将以上的重心性质进行了再推广得到了两个定理，我们可以将这两个定理加强为以下两个命题，证明类似文[6]在此不再证明．     

“解法辨析”之再辨析

文[1]分析了一类与二次函数有关的常见题型，并指出了文[2]解法的不足．我们分析后发现，文[1]题2、题3也存在严重疏漏，试分析如下：     

半相依回归系统参数的改进有偏估计

对于两个半相依回归方程组成的半相依回归系统(1．1)，当设计矩阵昊病态时，献[3]提出了两种有偏估计，献[4]提出了待定系数估计．本对[3]、[4]中的估计做了改进，得到两种改进有偏估计，并证明在一定的条件下，通过选取不同的ki和k，本的估计量在MDE-Ⅱ意义下优于[3]、[4]中的估计．     

关于椭圆离心率范围的一个漂亮的结论

文[1]，文[2]对两类椭圆的离心率范围的求解问题作了比较全面的探讨，对多种解题途径作了精辟的比较和提炼，读后得益非浅．同时，笔者也认为，文[1]，文[2]中提到的两类问题值得再探讨．     

圆锥曲线的一些性质

在文[1]，[2]，[3]中已给出了圆锥曲线的一些性质，本文再做进一步讨论，得到一系列更深入的结果．     

一道不等式试题的加强

文[1]，文[2]，文[3]对以下一道美国大学生数学竞赛试题进行了探究与推广：     

三角形和四面体的若干性质的推广

文[3]在文[1]，[2]的基础上得到了三角形和四面体的若干性质，本文试图给出它们的推广．     

半群环的右Artin性

本文研究了一般半群环的右Artin性的刻划问题，改进了JanOkniski在[3]中的结果，并给出了半群环是右Artin环的刻划．最后进一步指出在一定条件下，R[S1]和R[S1]的链条件是等价的．     

Generalized handles in graphs and connected sums of manifolds

Generalized handles in (n+1)-coloured graphs are defined. They are the n-dimensional analogue of a concept listed in [19] and generalizes the definition of combinatorial handle first introduced in [8] and successively investigated in[2],[12],[19],[26]. Then the operations of cancelling and cutting a generalized handle are studied. As a consequence some decomposition theorems about manifolds are proved. In particular, a graph-theoretical condition is obtained to recognize S^n–1 -bundles over S¹ as factors of a decomposition of a manifold in connected sum.Work performed under the auspicies of the G.N.S.A.G.A. of the C.N.R. (National Research Council of Italy) and financially supported by the M.P.I. of Italy within the Project Geometria delle Variet differenziabili     

Coeuklidische Hjelmslevgruppen

Over a three-dimensional metric vector space V over a field K of characteristic 2 can be defined geometrical structures in two ways. You can define reflections on lines either as reflections of V on one-dimensional non-isotropic subspaces of V or as involutory elements of the orthogonal group G of V with negative norm (in respect to a weak order of K). In this paper we characterize the geometry structures defined by the second method in the case that Ind V=0, dim rad V=1 via their reflection groups (G,S) — S the set of all reflections on lines. We show that these are certain Hjelmslevgroups. For an analogues characterization of the other seven classes of geometries see [1],[5], [7],[9].     

The obrechkoff integral transform: properties and relation to a generalized fractional calculus

This survey is devoted to one of the most general Laplace-type integral transforms, the so-called Obrechkoff integral transform, introduced and studied for the first time by Obrechkoff[25]. It has been modified by Dimovski [5],[6] and used as a basis of a Mikusinski-type operational calculus for the hyper-Bessel differential operators of arbitrary order. Later, in a series of papers Dimovski and Kiryakova [8],[9],[10] have found operational properties, complex and real inversion formulas, Abel-type theorems for the Obrechkoff transform. This theory has been further developed by Kiryakova [16],[17],[18] using the tools of the Meijer's G-functions and of the fractional calculus. Namely, a new definition as a G-transform has been given for the Obrechkoff transform. The hyper-Bessel operators themselves, have given rise to a new generalized fractional calculus and further extensive use of the G-functions. Many other generalized differentiation and integration operators happen to be special cases in this calculus, too. Special cases of the Obrechkoff transform have been "rediscovered" later by many authors. We give examples how their results could be derived from the general ones surveyed here.     

Composition operators on μ-Bloch type spaces

We characterize boundedness, closedness of the range and compactness for composition operators acting on μ-Bloch spaces, where μ is a positive continuous function defined on the interval 0 < t ≤ 1, that satisfy certain holomorphic extension properties. This extends results that appear in [15],[17],[8],[3].     

关于Banach空间中凸泛函的广义次梯度不等式

本文在前人^[1,2]的基础之上，以凸泛函的次梯度不等式为工具，将Jensen不等式推广到Banach空间中的凸泛函，导出了Banach空间中的Bochner积分型的广义Jensen不等式，给出其在Banach空间概率论中某些应用，从而推广了文献[3—6]的工作．     

线性变换下的模糊线性关系

在[1],[2],[3]基础上给出了某些线性变换下模糊线性无关向量组及模糊基的变换规律,指出任意模糊线性无关组都可扩充为模糊基,同时也给出了将模糊线性无关性组扩弃为模糊基的方法,。     

The Minimal Submanifolds in a Locally Symmetric and Conformally Flat Riemannian Manifold

In this paper,we extend two important theorem in[1],[2]to the minimal submanifolds in aLocally symmetric and conformally flat Riemannian mainfold N~(+p).When N~(+p)is a space S_(1)~(+p) of constantcurvature,our theorems reduce to the theorems of[1],[2].     

FIXED POINT INDEX THEORY FOR WEAKLY INWARD MAPPINGS

1IntroductionLetEbeaBanachspace,PcEaclosedconvexsetandletA:finP~Ebecompletelycontinuous,wherefiCEisanopenboundedset.ItiswelLknownthataAsedpointindexi(A,nnP,P)callbedefinedwheneverA(flnP)cpalldAx/xonoffnP,whichresultsinmanyfixedpointtheoremstodealwithvariousproblems.AsimpleanalysisofthemethodofdefiningtheindexrevealsthattherestrictionthatAmapsfinPtoPitselfisessential.FOrdetailswereferto[1,pp.286--291]andtheintroductionsectionof[2].Hereafter,wewillsaythatsllchmappingsareconemappings.On…     

多维平稳时间序列积分谱图的不变原理

用积分周期图估计平稳时间序列的谱函数，不论是高斯序列还是非高斯序列，其误差过程的不变原理都已被证明，许重光采用自迥归谱估计的积分估计谱函数也证明了误差过程的不变原理成立。本文讨论多维平稳时间序列，引进积分谱图来估计谱函数，证明了误差过程的不变原理在较弱的条件下成立。积分周期图是积分谱图的特例，因而［１］［３］［６］的一些结果是本文有关定理的特例。     

偶数阶中立型差分方程多正解的存在性

利用不动点指数理论,得到了高阶非自治非线性中立型差分方程多正解的存在性准则,推广了有关文献中的相关结论.