可分解半群的Morita等价

设S,R是可分解半群.记US-FAct={sM∈S-Act|SM=M且SHoms(S,M)≌M],给出了范畴US-FAct与UR-FAct等价的刻划;S分别强Morita等价于一个夹层半群、局部单位半群、幺半群和群的条件;S是完全单半群当且仅当S强Morita等价于一个群且对任何指标集I,S SHoms(S,i∈I S)→i∈I S,s t·f→(st)f,是同构.     

Arms races as iterated prisoner's dilemma games

Many important aspects of arms races are captured by the iterated prisoner's dilemma (IPD) game. In this analysis, strategies are developed and analyzed for IPD games which most resemble arms races; those which are finite, uncertain and time varying in length. It is shown that, under certain conditions, it can be rational to unilaterally cooperate following a series of mutual defection. A number of conclusions concerning arms race behavior are drawn.     

广义导子幂中心化子条件(英文)

设R是素环,U是R的极大右商环,C是R的扩展型心,I是R的非零理想,δ是R上的广义导子,a,b,q∈U.本文给出了恒等式(aδ(qx)-bx)~n=0(∈C在I上成立的充分必要条件,得到的结果推广了Herstein,Lanski,Lee的结论.     

Asymptotic power comparison of the chi-square and likelihood ratio tests

Summary A Hoeffding-type power comparison is made between the likelihood ratio and chi-square tests for a simple hypothesis in a multinomial. The power comparison is based on the fact that under an alternative hypothesis the distribution of the test statistic can be approximated by a normal distribution. The theory of large deviations is used to match the significance levels. This research was partially supported by the National Science Foundation Grant No. GP-33697X2, U.S. Energy Research and Development Agency Grant 7064100, Environmental Protection Agency Grant R805379-01-0 and U.S. Public Health Service Grant USPHS ES01299-15, at the University of California-Berkeley.     

An algorithm for constrained smoothing functions

In this paper we study a method for the approximation by a monotone smooth function of a discrete set of observations. By this method it is possible to obtain a completely automatic program. We show that the solution is monotone with probability tending to one and by the test examples that it is sufficient in the practical case.This work was supported by the Italian M.U.R.S.T.     

The category of modules over a monoidal category: Abelian or not?

LetA be an algebra in an abelian monoidal category M. We prove that the category of leftA-modules is abelian, wheneverA is right coflat. This paper was written while the author was member of G.N.S.A.G.A. with partial financial support from M.I.U.R.     

满足SR2*(R,I)条件的环的相对K2

设I是环R的理想,称(R,I)满足SR_2~*主(R,I)条件,如果它满足SR_2(R,I)条件,并且对任意的a,b∈I,存在一个I-单位半正则元t∈R,使得1 a(b-t)∈U(R,I),称环R带许多单位半正则元,如果它满足SR_2~*(R,R)条件,本文证明,如果(R,I)满足SR_2~*(R,I)条件,则S(R,I)=L(I)(?)(I)L(I)H(R,I),且相对K′_2群K′_2(R,I)(K_2(R,I))包含在H(R,I)((?)(R⊕I,O⊕I))中；进而,若I包含于R的中心,则K′_2(R,I)和K_(R,I)由相对Dennis-Stein符号生成,特别的,如果R是带许多单位半正则元的环,那么K_2(R)包含在H(R)中；进而,若R是交换的,则K_(2(R)由Dennis-Stein符号生成,在SR_2(R,I)条件下,本文证明了K_2(n,R,I)具有满稳定性,其中n≥3。     

Multipliers and singular integrals on exponential growth groups

We propose a simple abstract version of Calderón–Zygmund theory, which is applicable to spaces with exponential volume growth, and then show that important specific operators can be treated within this framework. Both authors are part of the European TMR network entitled ``Harmonic Analysis'. The first author was partially supported by KBN grant 5 P03A 050 20 and by the TMR network. The second author was partially supported by his university and by the Italian M.U.R.S.T     

Left (N,U)-coherent Dimensions and Excellent Extensions of Rings

Let S be an excellent extension of a ring R and U a flat right 5-module. We show in this paper that the left (N, U)-coherent dimension of S is equal to that of R.     

Complex dynamics and control of arms race

The aim of this paper is to show that asymmetric, nonlinear armament strategies may lead to chaotic motion in a discrete-time Richardson-type model on the arms race between two rival nations. Local bifurcation analysis reveals that ‘complicated’ dynamics will only occur if neither nation has an absolute advantage over the other one with respect to its level of armament and its capability to keep up the expenditures on armament. The calculation of Lyapunov exponents supports the existence of chaos. Since transitions to chaos can be identified with transitions to war, we use the Ott-Grebogi-Yorke-algorithm to stabilize the arms race model in the chaotic regime and improve the system's performance by making very small time-dependent changes of a parameter under control.     

The Impact of Microcomputers upon O.R.

In this paper we report the results of a survey on the impact of microcomputers (micros) upon O.R. Questionnaires were mailed to 216 O.R. workers throughout the U.K. A response rate of 35% was achieved. Nearly half of the groups surveyed have a ratio of at least one micro to one user. These micros are mainly used for spreadsheets, programming, graphics and word-processing.     

环的左(N,U)-凝聚维数

设R和S是环,U是平坦右R-模,V是平坦右S-模.本文中我们证明了(N,(U,V))-lc.dim(R⊕S)=sup((N,U)-lc.dim R,(N,V)-lc.dimS).     

变换图的直径及Brualdi猜想

设Ｒ＝（ｒ１，ｒ２…ｒｍ）及 Ｓ＝（Ｓ１，Ｓ２，…，Ｓｎ）为两个正整数向量，满足Σｍｉ＝１ｒｉ＝Σｎｊ＝１ｓｊ＝ Ｋ．记Ｇ（Ｒ，Ｓ）为（０，１）－矩阵类 Ｕ（Ｒ，Ｓ）的变换图．Ｂｒｕａｌｄｉ在文山中给出了 Ｇ（Ｒ，Ｓ）的直径厂（Ｇ（Ｒ，Ｓ））的一个上界：ｍｎ／２－１，并猜想Ｄ（Ｇ（Ｒ，Ｓ））≤ｍｎ／４．本文通过对有向图围长的研究得到了Ｄ（Ｇ（Ｒ，Ｓ））的一个新的上界：１／２ｍｎ－１／６ｔ（ｔ－１）（４ｔ＋１），其中Ｔ＝　　．     

金融危机下中美两国利率互换市场的特征及互动性分析

以2008～2009年中美两国利率互换市场的日交易数据为样本,分析比较了影响两国利率互换利差的主要因素,进而实证研究了危机期间中美两国利率互换市场的动态互动效应。结果表明:两国利率的水平和利率期限结构斜率是影响互换利差的主要因素,另外,中国的流动性溢价和美国的违约溢价对互换利差的影响也较为显著;研究发现:中美两国互换利差均受对方市场因素的影响,特别地,在金融危机期间,中美两国利率互换市场间存在着明显的互动效应,一方面,美国利率互换市场信息能够对中国利率互换市场产生较强的冲击,虽然冲击的程度受制于美国的经济状况;另一方面,中国市场对美国市场也形成了一定的反向冲击,且程度受制于中国的货币政策。     

Pattern Search Method for Discrete <Emphasis Type="Italic">L</Emphasis><Subscript>1</Subscript>–Approximation

We propose a pattern search method to solve a classical nonsmooth optimization problem. In a deep analogy with pattern search methods for linear constrained optimization, the set of search directions at each iteration is defined in such a way that it conforms to the local geometry of the set of points of nondifferentiability near the current iterate. This is crucial to ensure convergence. The approach presented here can be extended to wider classes of nonsmooth optimization problems. Numerical experiments seem to be encouraging. This work was supported by M.U.R.S.T., Rome, Italy.     

A particular class of symmetric spaces

Summary The metric of the general harmonic symmetric Riemannian 4-space expressed in tensor form is generalised to n dimensions, and it is verified that the space so obtained is symmetric, harmonic and complete, the underlying manifold being Euclidean. The metric of this space can be put in one of a number of simple canonical forms, by means of which the space can be classified. Under certain conditions the space is locally isometric to complex projective space or to a related space. To Enrico Bompiani on his scientific Jubilee I wish to aknowledge the hospitality of the University of Washington where this work was carried out as part of a research contract from the U. S. Office of Naval Research.     

A bisection algorithm for the numerical Mountain Pass

We propose a constructive proof for the Ambrosetti-Rabinowitz Mountain Pass Theorem providing an algorithm, based on a bisection method, for its implementation. The efficiency of our algorithm, particularly suitable for problems in high dimensions, consists in the low number of flow lines to be computed for its convergence; for this reason it improves the one currently used and proposed by Y.S. Choi and P.J. McKenna in [3]. Susanna Terracini: This work is partially supported by M.I.U.R. project “Metodi Variazionali ed Equazioni Differenziali Nonlineari”.     

关于素环广义导子和对称双导的几点备注

设R是素环,I是R的非零理想,如果R容许一个非单位映射的左乘子使得对所有x,y∈I满足δ(x°y)=x°y或δ(x°y) x°y=0,那么R可交换.此外,如果R是2-扭自由的素环,U是平方封闭的李理想,γ是伴随导子非零的广义导子,B:R×R→R是迹函数为g(x)=B(x,x)的对称双导,当下列条件之一成立时U为中心李理想(1)γ同态作用于U(2)2[x,y]-g(xy) g(yx)∈Z(R)(3)2[x,y] g(xy)-g(yx)∈Z(R)(4)2(x°y)=g(x)-g(y)(5)2(x°y)=g(y)-g(x)对所有的x,y∈U.     

Non-connected toric Hilbert schemes

We construct small (50 and 26 points, respectively) point sets in dimension 5 whose graphs of triangulations are not connected. These examples improve our construction in J. Amer. Math. Soc. 13:3 (2000), 611–637 not only in size, but also in that the associated toric Hilbert schemes are not connected either, a question left open in that article. Additionally, the point sets can easily be put into convex position, providing examples of 5-dimensional polytopes with non-connected graph of triangulations.Mathematics Subject Classification (2000): Primary 52B11; Secondary 52B20The main result in this paper was obtained in the fall of 2001, while I was a visiting professor in the Department of Mathematics, U.C. Davis, supported by U. C. Davis, M.S.R.I. and the Spanish Government. I am also partially supported by grant BFM2001–1153 of the Spanish Dirección General de Enseñanza Superior e Investigación Científica. The paper is dedicated to Bernd Sturmfels on his 40th birthday.     

Measuring the value of information: The case of data on the cost of producing cotton

Operational measurement methods may be developed to measure the value of information in the data reported by the U.S. Government. Illustrative measures for cost of cotton production statistics indicate that the benefits from these data in certain important uses may far exceed their costs. If similar measures could be provided for major Government data programmes, it would facilitate the development of a national data policy that is oriented toward decision making and improvements in economic growth, national well-being, and quality of life. Making these estimates would begin to provide the dollar values in important uses of information in the nation's data bases. These values are needed for allocating resources to maintain, refine, and develop fundamental data series. Cutting data expenditure in the absence of these value measures may be false economy indeed; because, reducing data series with very high benefit/cost ratios might well limit, if not reduce, living standards for many generations to come.Robert R. Nathan Associates, Inc.