共查询到19条相似文献,搜索用时 72 毫秒
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崔宁伟 《数学物理学报(A辑)》2006,26(B12):1047-1056
给出(α,β)-度量F=αФ(α,β)的S-曲率的计算公式.证得对一般的(α,β)-度量,当β为关于α长度恒定的Killing1-形式时,S=0.研究了Matsumoto-度量F=α^2/(α-β)和(α,β),度量F=α+εβ+κ(β^2/α)的S-曲率,证得S=0当且仅当β为关于α长度恒定的Killing1-形式.同时还得到这两类度量成为弱Berwald度量的充要条件,其中Ф(s)为光滑函数,α(y)=√aij(x)y^iy^j为黎曼度量,β(y)=bi(x)y^i为非零1-形式且ε,κ≠0为常数. 相似文献
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设R和S是环,U是平坦右R-模,V是平坦右S-模.本中我们证明了(N,(U,V))-lc.dim(R S)=sup((N,U)-lc.dimR,(N,V)-lc.dimS). 相似文献
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(M,N)树的几个判定定理 总被引:5,自引:0,他引:5
(m,n)树是图论中树的概念在n维复形上的推广。关于n维复形和它的(m,n)回路,(m,n)连通,(m,n)简单,纯n维复形,(m,n)树等概念见文献[3],[4]。 用a_k(K)表复形K中的k维单形个数。又记 相似文献
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ZhongKuiLIU JavedAHSAN 《数学学报(英文版)》2004,20(1):105-114
Let U be a flat right R-module and N an infinite cardinal number.A left R-module M is said to be (N,U)-coherent if every finitely generated submodule of every finitely generated M-projective module in σ[M] is (N,U)-finitely presented in σ[M].It is proved under some additional conditions that a left R-module M is (N,U)-coherent if and only if Л^Ni∈I U is M-flat as a right R-module if and only if the (N,U)-coherent dimension of M is equal to zero.We also give some characterizations of left (N,U)-coherent dimension of rings and show that the left N-coherent dimension of a ring R is the supremum of (N,U)-coherent dimensions of R for all flat right R-modules U. 相似文献
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(B)空间中的凝聚映像方程 总被引:4,自引:0,他引:4
如所周知,有关(B)空间X中的映像方程 θ=T_1(x)-x (1)的研究,是有重要的理论与应用价值的.例如,在处理一些理论与实际问题的时候,常可把它们纳入有关(1)的解或(相应映像的)本征元等问题的框架之中. 考虑方程(1).文中考虑的映像T_1:C→X是个凝聚映像.又,C是X的子集. 相似文献
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关于迭代方程G(f(x),f ̄(n_1)(x),…,f ̄(n_k)(x))=F(x)的连续解司建国(滨州师范专科学校数学系,山东256604)关键词迭代方程,连续解,存在性;唯一性,稳定性.分类号AMS(1991)39B12/CCLO175.14本文... 相似文献
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本文用临界点理论中的能量最小原理得到了一类具(q(t),P(t))-Laplacian项的二阶非自治系统存在周期解的充分条件. 相似文献
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本文利用概率方法讨论了关于Riemann Zeta函数ξ(i)的卷积∑^k-2 i=2 ∑(k-i),k≥4,Euler证明了这个卷积与级数∑ n≥1 Hn/n^(k-1)有关,使用Stirling展开我们发现了一个新的不同的结果. 相似文献
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Srivastava gave an asymptotically efficient and consistent sequential procedure to obtain a fixed-width confidence region for the mean vector of any p-dimensional random vector with finite second moments. For normally distributed random vectors, Srivastava and Bhargava showed that the specified coverage probability is attained independent of the width, the mean vector, and the covariance matrix by taking a finite number of observations over and above T prescribed by the sequential rule. However, the problem of showing that E(T−n0) is bounded, where n0 is the sample size required if the covariance matrix were known, has not been available. In this paper, we not only show that it is bounded but obtain sharper estimates of E(T) on the lines of Woodroofe. We also give an asymptotic expansion of the coverage probability. Similar results have recently been obtained by Nagao under the assumption that the covariance matrix Σ=∑ki=1 σiAi and ∑ki=1 Ai=I, where Ai's are known matrices. We obtain the results of this paper under the sole assumption that the largest latent root of Σ is simple. 相似文献
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Majid Asadi 《Journal of multivariate analysis》1998,67(2):190-202
Recently attempts have been made to characterize probability distributions via truncated expectations in both univariate and multivariate cases. In this paper we will use a well known theorem of Lau and Rao (1982) to obtain some characterization results, based on the truncated expectations of a functionh, for the bivariate Gumbel distribution, a bivariate Lomax distribution, and a bivariate power distribution. The results of the paper subsume some earlier results appearing in the literature. 相似文献
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本文应用概率论知识对乙肝表面抗原检测方法进行了探讨 ,建立了相应的数学模型 ,优化了检测模式 相似文献
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Tamás Szántai 《Annals of Operations Research》2000,100(1-4):85-101
Improved bounds and simulation procedures on the value of the multivariate normal probability distribution function value are given in the paper. The author's variance reduction technique was based on the Bonferroni bounds involving the first two binomial moments only. The new variance reduction technique is adapted to the most refined new bounds developed in the last decade for the estimation the probability of union respectively intersection of events. Numerical test results prove the efficiency of the simulation procedures described in the paper. 相似文献
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基于矩阵斜消变换的最大公因式求解 总被引:4,自引:0,他引:4
郁金祥 《数学的实践与认识》2005,35(11):78-82
提出了矩阵的第一、第二斜消变换概念,并利用其得到求解多个多项式的最大公因式的方法.提供了相关的证明及具体的应用实例. 相似文献
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用初等方法得到了Sierpinski地毯的Hausdorff测度. 相似文献
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We use a simple example (the projective plane on seven points) to give an introductory survey on the problems and methods in finite geometries — an area of mathematics related to geometry, combinatorial theory, algebra, group theory and number theory as well as to applied mathematics (e.g., coding theory, information theory, statistical design of experiments, tomography, cryptography, etc.). As this list already indicates, finite geometries is — both from the point of view of pure mathematics and from that of applications related to computer science and communication engineering — one of the most interesting and active fields of mathematics. It is the aim of this paper to introduce the nonspecialist to some of these aspects.To Professor Günter Pickert on the occasion of his 65th birthday 相似文献