可估子空间上一般Gauss—Markoff模型的比较

对于两个线性模型ｄ１＝Ｌ（Ｘ１，β，Ｖ１）和ｄ２＝Ｌ（Ｘ２β，Ｖ２），其中Ｖ１和Ｖ２是已知的对称非负定矩阵，我们在可估子空间μ（Ａ）上对它们进行了比较。得到了ｄ１≥ｄ２（μ（Ａ））的一个充要条件。最后，我们在可估子空间上比较了带多余参数的两个线性模型，得到了一个充要条件。     

线性变换对带约束奇异线性模型的条件G—M估计的影响

考虑带约束奇异线性模型Y=Xβ＋ε，Lβ＝0，E（ε）＝0，cov（ε）＝σ~2V，其中V为非负定矩阵，X为任意秩．文章研究了观察向量Y的线性变换对回归系数条件可估函数Sβ的G－M估计的影响，并将条件可估子空间μ（X'L'）划分成Ω＋Ω_＋Ω_2.当μ（S'）Ω时，Sβ的条件G-M估计在模型变化后其优良性不变；当μ（S'）Ω_1时，模型变化后Sβ仍可估，但Sβ的条件G－M估计的方差要变大；当μ（S'）Ω_2时，Sβ不可估．     

二次损失下回归系数的线性Minimax估计

设有线性模型EY=Xβ,CovY=σ~2V,这里X和 V_(:nxn)>0已知矩阵,β∈R~p 和σ~2>0都是参数.本文估计 Sβ,选取损失函数L(d,Sβ)=其中 Sβ是可估的,并给出了在线性估计类中唯一的一个线性 minimax 估计.     

二次损失下回归系数的线性Minimax估计

设有线性模型 EY=Xβ CovY=σ~2V, 这里X: _(nxp),和V: _(nxn)>0已知矩阵,β∈R~P和σ~2>0都是参数。本文估计Sβ,选取损失函数 L(d,Sβ)=((d-Sβ)′(d-Sβ))/(σ~2+β′X′V~(-1)Xβ), 其中Sβ是可估的,并给出了在线性估计类中唯一的一个线性minimax估计。     

线性模型中参数的线性估计的可容许性

本文的主要结果如下:1.假定 n 维向量 Y 适合EY=θ,VarY=σ~2V,V>0,则在二次型损失函数(LY-Sθ)′(LY-Sθ)下,在线性估计类中,LY 是 Sθ的可容许估计的充要条件是(a)LYS′对称,(b)LVL′≤LVS′,(c)rk(L-S)V=rk(L-S),其中 L,S 均为r×n 阵。2 假定在 Ganss-Markov 换型(Y,Xβ,σ~2V,V≥0)下,Sβ是可估的,则在矩阵损失函数(LY-Sβ)(LY-Sβ)′/σ~2下,在线性估计类中,LY 是 Sβ的可容许估计的充要条件是:(a)μ(VL′)μ(X),(b)LX=S 或 LX≠S 时,LXTX′L′-STS′ a(LX-S)T(LX-S)′≥0,对所有的a∈(0,1)不成立,其中T=X~ (V-VH(V~(1/2)H)~ V(1/2))X′~ ,H=I-XX~ .     

线性模型中参数的线性估计的可容许性

本文的主要结果如下: 1.假定n维向量Y适合 EY=θ,VarY=σ~(2V),V≥O,则在二次型损失函数(Ly-Sθ)′(Ly-Sθ)下,在线性估计类中,LY是Sθ的可容许估计的充要条件是(α)LVS′地称,(b)LVL′≤LVS′,(c)rk(L-S)V=rk(L-S),其中L,S均为r×n阵。 2 假定在Ganss-Markov换型(Y,Xβ,σ~(2V),V≥O)下,Sβ是可估的,则在矩阵损失函数(LY—Sβ)(LY—Sβ)′/σ~2下,在线性估计类中,LY是Sβ的可容许估计的充要条件是: (a)μ(VL′)μ(X), (b)LX=S或LX≠S时, LXTX′L′-STS′ a(LX-S)T(LX-S)′≥O。对所有的α∈(0,1)不成立,其中     

一般正态线性模型中可估函数的线性Minimax估计

对于一般正态线性模型y～N(Xβ,σ2V),这里X和V≥0是已知矩阵,β∈Rp和σ2＞0是未知参数,在二次损失下我们研究了可估函数DXβ的线性估计在一切估计类中的Minimax性,得到了DXβ的唯一线性Minimax估计(有关唯一性在几乎处处意义下理解).     

回归系数的非齐次线性估计的可容许性

考虑线性模型丁“Y一召…月二‘L刀Y一u”V,V>o,O’“为简便计,记为之Y,了月,砂V,V>0).若召是:x,阵,伺题.未知当习月可估时, (1)我们研究估计尽月的 RaoL刀给出了,在二次型损失函数 (‘一习月丫(d一习月)(2)下,S月的齐次线性估计L了在齐次线性估计类中是可容许估计的充要条件.本文考虑月月的非齐次线性估计L了+a的可容许性.在二次型损失函数下得到了LY十a在非齐次线性估计类中是习月的可容许估计的充要条件. 称R(S月,。,,d、~E(‘一习月)‘(d一召月)为习月的估计d的风险.若d,,d。是S尽的两个估计,当R〔泞月,。,,J,)一R(习月,a,,d:…     

矩阵损失下约束线性模型中回归系数的线性可容许估计

考虑约束线性模型Mr={Y,Xβ,σ2V|Rβ=r}其中x列满秩,V为正定矩阵.在二次损失下,Baksalary. J. K和Markiewicz,A得到了回归系教β的线性估计在非齐次线性估计类中可容许的充分必要条件,利用吴启光在无约束线性模型关于回归系数线性可容许估计的结果,对约束线性模型Mr我们得到结果如下在矩阵损失下回归系数β的线性估计AY+g在非齐次线性估计类中可容许当且仅当[i]XAV对称;[ii]R(A) R(U) [iii]AXU=U,g=(AX-I)R+r或AXU≠U时,有r(AX) (-∞,0)∪(1,+∞).其中R(U)=N(R),U为列正交矩阵.     

带约束的回归系数的线性估计的可容许性

在本文中,我们针对带齐次线性等式约束的线性模型Y=Xβ+ε,ε～(0,σ~2V),Hβ=0,给出了回归系数的最佳线性无偏估计的较简单的表达式以及Sβ的估计LY(LY+α)在齐次线性估计类(线性估计类)中可容许的充要条件。     

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.     

Instructions for Authors

<正>Submission Authors must use LaTeX for typewriting,and visit our website www.actamath.com to submit your paper.Our address is Editorial Office of Acta Mathematica Sinica,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100190,P.R.China.     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijin,China The International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

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.     

A unified approach to certain problems of best local approximation

In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.     

Towards Excellence in Science Chinese Academy of Sciences

<正>May 26,2014,Beijing Science is a human enterprise in the pursuit of knowledge.The scientific revolution that occurred in the 17th Century initiated the advances of modern science.The scientific knowledge system created by     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

<正>August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

Bounds for the zeros of polynomials

Let P(z)=∑↓j=0↑n ajx^j be a polynomial of degree n. In this paper we prove a more general result which interalia improves upon the bounds of a class of polynomials. We also prove a result which includes some extensions and generalizations of Enestrǒm-Kakeya theorem.