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1.
加性DEA模型与规模收益   总被引:1,自引:0,他引:1  
[1]给出了用C^2R模型或C^2GS^2模型来判断决策单元的规模收益情况的定理,指出它有时失效。对DEA有效(C^2GS^2)的决策单元,本用加性DEA模型来有效地判断其规模收益情况。  相似文献   

2.
刘小松 《数学学报》2022,(5):783-796
本文主要建立了复Banach空间单位球上与C^(n)中单位多圆柱上带有具体参数表示的一类螺型映射子族各项齐次展开式的精细估计.特别地,k+1阶齐次展开式的结果是精确的.同时给出复Banach空间单位球上与C^(n)中单位多圆柱上带有参数表示的一类k折对称双全纯螺型映射子族各项齐次展开式的估计,且k+1阶齐次展开式的结果也是精确的.所得结果包含一些先前文献的许多已有结论.  相似文献   

3.
设X是一个实的Hausdorff拓扑向量空间,Y是一个实的局部凸向量空间,C是Y中的闭凸锥,K(?)X是一个紧子集.F:X×X→Y是一个双向量函数,G:K→2K是一个集合值映射.我们考虑下面的强拟均衡问题:存在x∈G(x),使得对任意的y∈G(x),成立F(x,y)∈C.本文证明了当F是半连续时,上述问题解的存在性结论.  相似文献   

4.
证明了Orlicz序列空间lm的粗系数R(lm)=2/supky,这里‖y‖0n=1ky=min{k>0:‖y‖0n=1/k(1+PN(ky))}.  相似文献   

5.
徐新萍 《东北数学》2004,20(1):41-50
Let G be a graph. An independent set Y in G is called an essential independent set (or essential set for simplicity) if there is {Y1, Y2} 包含于Y such that dist (y1,y2)=2. In this paper, we use the technique of the vertex insertion on l-connected (l=k or k 1, k≥2) graphs to provide a unified proof for G to be hamiltonian, or hamiltonian-connected. The sufficient conditions are expressed an inequality on ∑i=1 K|N(Yi)| b|N(y0)| and n(Y) for each essential set Y={y0,y1,…,yk}, where b (1≤b≤k)is an integer,Yi={yi,yi-1,…,yi-(b-1}包含于Y\{y0} for i属于V(G):dist(v,Y)≤2}|.  相似文献   

6.
本文得到了含双参数x,y的Ramsey数的新上、下界公式,且初步研究了它的应用,证明了R(K6-e,K6)≤116和R(K6-e,K7)≤202.  相似文献   

7.
章前 《应用数学》1998,11(4):49-52
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.  相似文献   

8.
矩阵损失下多元统计中期望向量的线性Minimax估计   总被引:3,自引:0,他引:3  
设yi,y2,…,yn,i.i.d,Ey1=β,Cov(y1)=∑,这里ε∈RP和∑>0未知,我们估计β,估计类为L={Liyi:Li为p阶常数方阵,i=1,2,…,n},损失函数为其中V1,V2>0已知,我们研究β的一个线性估计在L中的Minimax性.主要结果是1.当V2=kV1,k>0时,β的唯一的Ⅰ-型线性Minimax估计为Y/(1+),其中Y==2.当V2=kV1对所有k>0不成立,但V1V2=V2V1时,β的Ⅰ-型线性Minimax估计不存在.3.当V1V2=V2V1时,β的Ⅱ-型线性Minimax估计为,这个估计在V1,V2满足条件V1V2=V2V1下变化时,构成了集合{AY:A对称,A的特征根均在(0,1)中}.4.对于一般的V1,V2;Y仍是β的Ⅱ-型线性Minimnax估计,这个估计在V1,V2任意变化时,构成了集会{AY:A的特征根是实的,特征根全在(0,1)中,且A只具有线性初等因子}.  相似文献   

9.
We find an upper viscosity solution and give a proof of the existence-uniqueness in the space C^∞(t∈(0,∞);H2^s+2(R^n))∩C^0(t∈[0,∞);H^s(R^n)),s∈R,to the nonlinear time fractional equation of distributed order with spatial Laplace operator subject to the Cauchy conditions ∫0^2p(β)D*^βu(x,t)dβ=△xu(x,t)+f(t,u(t,x)),t≥0,x∈R^n,u(0,x)=φ(x),ut(0,x)=ψ(x),(0.1) where △xis the spatial Laplace operator,D*^β is the operator of fractional differentiation in the Caputo sense and the force term F satisfies the Assumption 1 on the regularity and growth. For the weight function we take a positive-linear combination of delta distributions concentrated at points of interval (0, 2), i.e., p(β) =m∑k=1bkδ(β-βk),0〈βk〈2,bk〉0,k=1,2,…,m.The regularity of the solution is established in the framework of the space C^∞(t∈(0,∞);C^∞(R^n))∩C^0(t∈[0,∞);C^∞(R^n))when the initial data belong to the Sobolev space H2^8(R^n),s∈R.  相似文献   

10.
设(X,d1,f1∞)与(Y ,d2,g1,∞)为两个非自治动力系统,h是从(X,d1,f.∞)到(Y,d2,g1∞)的拓扑半共轭.通过对自治动力系统中的h一极小覆盖的研究,本文得到了以下结论:1)对于任意的Y∈Y及X∈h-1(y),orb(x,f1∞)被h映射为orb(y,g1∞),w(x,f1∞)被h映射为w(y,g1∞);2)在(X,d1,f1∞)中引入关于拓扑半共轭的h-极小覆盖的定义,证明了h一极小覆盖的存在性;3)对于任意的XEX和Y∈Y,在(w(z,f1∞),f1∞。(x,f1,∞)与(w(y,g∞),g1,∞(y,g1∞))均构成原系统的子系统的前提下,R(f1∞)被h映射为R(g1∞).这些结论丰富了非自治动力系统的内容.  相似文献   

11.
Returns-to-scale (RTS) characterizations and the underlying notion of scale elasticity are important characteristics of production frontiers, in both parametric and nonparametric methodologies of efficiency and productivity analysis. In practical applications of these methodologies, the model of technology is often experimented with and modified before it is finalized, which involves, for example, a change of the data set, incorporation, exclusion or aggregation of inputs and outputs, or experimentation with the production assumptions, or axioms, on which the model is based. While it is well-known how such modifications of technology affect the efficiency scores, their effect on the RTS characterization of the production frontier has not been sufficiently explored in the literature. In this paper we obtain several general results that clarify this issue.  相似文献   

12.
证明了如何选取矩阵X,Y和Z使得下面的分块矩阵(AXYZ)取得它的极大秩和极小秩,这里A∈C~(m×n)是一个已知矩阵,X∈C~(m×k),Y∈C~(p×n)和Z∈C~(p×k)是三个任意矩阵.  相似文献   

13.
This paper analyses the mechanisms through which binding finance constraints can induce debt-constrained firms to improve technical efficiency to guarantee positive profits. This hypothesis is tested on a sample of firms belonging to the Italian manufacturing. Technical efficiency scores are computed by estimating parametric production frontiers using the one stage approach as in Battese and Coelli [Battese, G., Coelli, T., 1995. A model for technical efficiency effects in a stochastic frontier production function for panel data. Empirical Economics 20, 325–332]. The results support the hypothesis that a restriction in the availability of financial resources can affect positively efficiency.  相似文献   

14.
康梅 《运筹与管理》2007,16(4):144-148
企业经营环境外部系统因素的不确定性是影响企业所有者与经营者之间委托代理问题解决的主要因素,目前还没有文献系统建立企业经营环境信息的识别方法。本文利用技术效率评价中的理论来研究企业经营环境信息的识别问题。基于(k,y)空间的生产可能集与技术效率发展了描述不同行业投入产出差别的技术系数,给出行业获利性波动的时序识别方法。这些方法对弱化企业所有者与经营者之间信息非对称程度,解决二者之间的委托代理问题提供了一个有效途径。  相似文献   

15.
Banach空间中不适定线性算子方程的最佳逼近解   总被引:1,自引:0,他引:1  
设X,Y为Banach空间,T为从X到Y的线性算子.T的值域R(T)≠Y且为逼近紧子空间,T的零空间N(T)≠{θ}.证得不适定算子方程Tx=y的最佳逼近解对任意y∈Y均存在的充分必要条件是N(T)为X的迫近子空间.  相似文献   

16.
While estimating parametric production models with risk, one faces two main problems. The first problem is associated with the choice of functional forms on the mean production function and the risk (variance) function. The second problem is associated with the specification of the risk preference function. In a parametric model the researcher chooses some ad hoc functional form on all these. It is obvious that the estimated (i) technology (mean production function), (ii) risk and (iii) risk preference functions are affected by the choice of functional form. In this paper we consider an estimation framework that avoids assuming parametric functions on all three. In particular, this paper deals with nonparametric estimation of the technology, risk and risk preferences of producers when they face uncertainty in production. Uncertainty is modeled in the context of production theory where producers’ maximize expected utility of anticipated profit. A multi-stage nonparametric estimation procedure is used to estimate the production function, the output risk function and the risk preference function. No distributional assumption is made on the random term representing production uncertainty. No functional form is assumed on the underlying utility function. Rice farming data from Philippines are used for an empirical application of the proposed model. Rice farmers are, in general, found to be risk averse; labor is risk decreasing while fertilizer, land and materials are risk increasing. The mean risk premium is about 3% of mean profit.  相似文献   

17.
对文[1]中有关DEA有效(C2R)的定理4,本文给出了在某种条件下的逆定理,以便简化DEA有效性(C2R)的判断.  相似文献   

18.
In this paper, we propose a parametric approach to the stability theory for the solution set of a semi-infinite linear inequality system in the n-dimensional Euclidean space . The main feature of this approach is that the coefficient perturbations are modeled through the so-called mapping of parametrized systems, which assigns to each parameter, ranging in a metric space, a subset of . Each vector of this image set provides the coefficients of an inequality in and the whole image set defines the inequality system associated with the parameter. Thus, systems associated with different parameters are not required to have the same number (cardinality) of inequalities. The paper is focused mainly on the structural stability of the feasible set mapping, providing a characterization of the Berge lower-semicontinuity property. The role played by the strong Slater qualification is analyzed in detail.This research has been partially supported by Grant PB98-0975 from DGES (Spain), Grant BFM2002-04114-C02 (01–02) from MCYT (Spain), FEDER (European Union), and Bancaja-UMH (Spain).  相似文献   

19.
Semiparametric models with both nonparametric and parametric components have become increasingly useful in many scientific fields, due to their appropriate representation of the trade-off between flexibility and efficiency of statistical models. In this paper we focus on semi-varying coefficient models (a.k.a. varying coefficient partially linear models) in a “large n, diverging p” situation, when both the number of parametric and nonparametric components diverges at appropriate rates, and we only consider the case p=o(n). Consistency of the estimator based on B-splines and asymptotic normality of the linear components are established under suitable assumptions. Interestingly (although not surprisingly) our analysis shows that the number of parametric components can diverge at a faster rate than the number of nonparametric components and the divergence rates of the number of the nonparametric components constrain the allowable divergence rates of the parametric components, which is a new phenomenon not established in the existing literature as far as we know. Finally, the finite sample behavior of the estimator is evaluated by some Monte Carlo studies.  相似文献   

20.
In this paper, we define an analog of power series functions over R, when R is replaced by K = k((x))τ , a field of generalized power series with coefficients in an ordered field k and exponents in an ordered abelian group τ. To this end for any power series S(Y)ε K[[Y]] and any y ε K, we define a notion of convergence of S(y). Thus to any power series S(Y) is associated a partial function S : K→ K. We show that these partial functions have a lot of similarities with analytic functions over R. Then we prove properties of zeros of such functions which extend properties of roots of polynomials over k((x))τ.  相似文献   

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