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1.
This paper disentangles the topological assumptions of classical results (e.g.,Walker, 1977 on the existence of maximal elements from rationality conditions. It is known from the social choice literature that under the standard topological conditions—with no rationality assumptions on preferences—there is an element such that the upper section of strict preference at that element is minimal in terms of set inclusion, i.e., the uncovered set is nonempty. Assuming the finite subordination property, a condition that weakens known acyclicity and convexity assumptions, each such uncovered alternative is in fact maximal. Implications are a generalization of a result of Yannelis and Prabhakar (1983) on semi-convexity, an extension of Fan’s (1961) lemma on KKM correspondences, and the existence of fixed points for subordinate convex correspondences generalizing the work of Browder (1968).  相似文献   

2.
We consider the core-periphery model [P. Krugman, Increasing returns and economic geography, Journal of Political Economy 199 (1) (1991) 483–499]. The nature and stability of the possible steady states of the model have been made progressively precise; [M. Fujita, P. Krugman, A. Venables, The Spatial Economy. Cities, Regions and International Trade, MIT Press, Cambridge, 1999; R. Baldwin, R. Forslid, Ph. Martin, G. Ottaviano, F. Robert-Nicoud, Economic Geography and Public Policy, Princeton Univ. Press, 2003]. In that model as well as in all the new economic geography models that have been derived from it, the short-run (instantaneous) equilibrium is implicitly determined by the current labor distribution across regions. The numerical computations used so far to determine the short-run equilibrium, tend to suggest its existence. In this paper, an existence and uniqueness proof of short-run equilibrium is provided.  相似文献   

3.
This paper motivates and introduces a two-stage method of estimating diffusion processes based on discretely sampled observations. In the first stage we make use of the feasible central limit theory for realized volatility, as developed in [Jacod, J., 1994. Limit of random measures associated with the increments of a Brownian semiartingal. Working paper, Laboratoire de Probabilities, Universite Pierre et Marie Curie, Paris] and [Barndorff-Nielsen, O., Shephard, N., 2002. Econometric analysis of realized volatility and its use in estimating stochastic volatility models. Journal of the Royal Statistical Society. Series B, 64, 253–280], to provide a regression model for estimating the parameters in the diffusion function. In the second stage, the in-fill likelihood function is derived by means of the Girsanov theorem and then used to estimate the parameters in the drift function. Consistency and asymptotic distribution theory for these estimates are established in various contexts. The finite sample performance of the proposed method is compared with that of the approximate maximum likelihood method of [Aït-Sahalia, Y., 2002. Maximum likelihood estimation of discretely sampled diffusion: A closed-form approximation approach. Econometrica. 70, 223–262].  相似文献   

4.
This paper develops a regression limit theory for discrete choice nonstationary panels with large cross section (N) and time series (T) dimensions. Some results emerging from this theory are directly applicable in the wider context of M-estimation. This includes an extension of work by Wooldridge [Wooldridge, J.M., 1994. Estimation and Inference for Dependent Processes. In: Engle, R.F., McFadden, D.L. (Eds.). Handbook of Econometrics, vol. 4, North-Holland, Amsterdam] on the limit theory of local extremum estimators to multi-indexed processes in nonlinear nonstationary panel data models.It is shown that the maximum likelihood (ML) estimator is consistent without an incidental parameters problem and has a limit theory with a fast rate of convergence N1/2T3/4 (in the stationary case, the rate is N1/2T1/2) for the regression coefficients and thresholds, and a normal limit distribution. In contrast, the limit distribution is known to be mixed normal in time series modeling, as shown in [Park, J.Y., Phillips, P.C.B., 2000, Nonstationary binary choice. Econometrica, 68, 1249–1280] (hereafter PP), and [Phillips, P.C.B., Jin, S., Hu, L., 2007. Nonstationary discrete choice: A corrigendum and addendum. Journal of Econometrics 141(2), 1115–1130] (hereafter, PJH).The approach is applied to exchange rate regime choice by monetary authorities, and we provide an analysis of the empirical phenomenon known as “fear of floating”.  相似文献   

5.
朱长青 《价值工程》2014,(3):258-259
首先阐述了将数学建模思想融入高等数学教学内容中的意义,接着从高等数学中的基本概念和基本定理出发,通过具体案例说明如何将数学建模案例融入在高等数学教学中。最后给出了根据高等数学内容选编的典型建模案例。  相似文献   

6.
Abstract.  During the last two decades, the discrete choice modeling of labor supply decisions has become increasingly popular. Within the literature adopting this approach, however, there are two potentially important issues that so far have not been given the attention they might deserve. A first issue concerns the procedure by which the discrete alternatives are selected to enter the choice set. Most authors choose (not probabilistically) a set of fixed points identical for every individual. Some authors adopt instead a sampling procedure and also assume that the choice set may differ across households. A second issue concerns the availability of the alternatives. Most authors assume all the values of hours of work within some range are equally available. At the other extreme, some authors assume only two or three alternatives (for example, nonparticipation, part-time and full-time) are available for everyone. Some studies account instead for the fact that not all the hour opportunities are equally available to everyone specifying a probability density function of opportunities for each individual. In this paper we explore by simulation the implications of (i) the procedure used to build the choice set (fixed alternatives versus sampled alternatives); (ii) accounting or not accounting for a different availability of alternatives. The results of the evaluation performed in this paper show that the way the choice set is represented has little impact on the fitting of observed values, but a more significant and important impact on the out-of-sample prediction performance. Thus, the treatment of the choice sets might have a crucial effect on the result of policy evaluations.  相似文献   

7.
王叶青  安天庆 《价值工程》2011,30(34):181-182
文章中我们讨论二阶hamilitonian系统周期解的存在性,利用鞍点定理,我们得到了一个新的二阶hamiltonion系统周期的存在性。  相似文献   

8.
李新征 《物流技术》2005,(11):49-52
首先根据实际问题分析了物流配送网络优化模型的各个关键组成部分,包括优化目标、决策变量和约束条件,并针对目前物流配送网络优化算法中存在的一些问题提出了一种新的算法,其核心是佳点集遗传算法。该算法编码采用prufer num ber结构,变异和交叉概率自适应选择。  相似文献   

9.
建设项目投资规模的设计直接关系到企业的经济效益。在对固网运营企业投资项目进行可行性研究时,对投资规模的优化是值得深入研究的问题。由于对投资项目的评价有多个指标,本文分别研究了以净现值最大和以净现值率最大为决策准则的投资规模决策模型,以期为固网投资决策提供参考。  相似文献   

10.
    
Continuous exact non-atomic games are naturally associated to certain operators between Banach spaces. It thus makes sense to study games by means of the corresponding operators. We characterize non-atomic exact market games in terms of the properties of the associated operators. We also prove a separation theorem for weak compact sets of countably additive non-atomic measures, which is of independent interest.  相似文献   

11.
万明 《上海管理科学》2011,33(6):108-110
高校固定资产管理工作长期以来面临的各种难题,与传统思维下“重物轻人”的观念有着深刻的联系。以人为本的管理理念以“人”为中心,通过柔性化的管理手段,为新形势下高校提升固定资产的管理效率和水平,提供了新的思路。它将有利于激发管理者的主体性和创造性,在完成管理目标的同时,促进自身价值的实现,使“人”和“物”在和谐有序的状态中协调发展。  相似文献   

12.
文章介绍了永久变形的发生机理,拉伸和压缩永久变形的差异及应用现状,拉伸和压缩永久变形测试在实际应用中的差别以及拉伸永久变形测试的必要性,拉伸永久变形对伸张疲劳性能的影响等,说明了在实际应用中不能忽视拉伸永久变形测试,并建议尽快建立相关的国家标准。  相似文献   

13.
固定资产折旧制度分析   总被引:1,自引:0,他引:1  
固定资产折旧制度与会计信息质量、与企业乃至社会经济的运行密切相关。我国现行固定资产折旧制度对不同折旧计算方法的适用对象规定不明确、折旧计算方法与配比原则和一贯性原则相悖、对固定资产价值耗费计量不足。  相似文献   

14.
投资效益审计目标及内容研究   总被引:2,自引:1,他引:2  
随着我国公共财政体制改革的不断深入,政府投资方向的调整和职能的转变,如何开展投资效益审计,是当前投资审计工作必须研究探索的重要课题,也是今后投资审计工作深化和发展的方向。本文从投资效益审计的目标及内容两个方面进行分析,旨在为探索投资审计提供一定的理论依据。  相似文献   

15.
    
Lothar Heinrich 《Metrika》1993,40(1):67-94
Summary This paper presents a method for the estimation of parameters of random closed sets (racs’s) in ℝ d based on a single realization within a (large) convex sampling window. The essential idea first applied by Diggle (1981) in a special case consists in defining the estimation by minimizing a suitably defined distance (called contrast function) between the true and the empirical contact distribution function of the racs under consideration, where the most relevant case of Boolean models is discussed in details. The resulting estimates are shown to be strongly consistent (if the racs is ergodic) and asymptotically normal (if the racs is Boolean) when the sampling window expands unboundedly.  相似文献   

16.
Urban agglomeration, wages and selection: Evidence from samples of siblings   总被引:1,自引:0,他引:1  
The large and significant relationship between city population and wages has been well-established in the agglomeration literature, and the influence of selection effects on this wage premium is important. This paper contributes new evidence to the understanding of this premium by using two different data sets of siblings in order to estimate the agglomeration premium while controlling for unobserved heterogeneity with a family-specific fixed effect. The inclusion of a familial fixed effect into the regression framework makes the city size wage premium insignificant, and there is a large return to a variable representing the correlation between familial ability and residence in an urban area in all of the data sets used in the analysis. The results are discussed in the context of the existing literature, and they demonstrate the importance of family background and selection effects for interpreting the agglomeration premium, which is small in the fixed effects regression.  相似文献   

17.
In this paper we consider a fixed-effects stochastic frontier model. That is, we have panel data, fixed individual (firm) effects, and the usual stochastic frontier analysis (SFA) composed error.  相似文献   

18.
离散选择模型的基本原理及其发展演进评介   总被引:10,自引:0,他引:10  
离散选择模型的研究真正兴起于19世纪50年代末,属于微观计量经济学的范畴。该模型能够对个体和家庭行为进行经验性的统计分析,因而在经济学和其他社会科学中得到广泛的应用。本文从离散选择模型的基本性质及效用最大化的理论背景出发,指出logit模型虽然使用的是最早并且最为广泛的离散选择模型,但是其存在着三大局限性:不能表示随机口味的变化、暗含成比例的替代形式和不能处理不可观测因素在不同期间相关的情形。GEV(含嵌套logit)、probit和混合logit模型等其他的离散选择模型,很大程度上都是为了避免这些限制而产生并发展起来的。  相似文献   

19.
    
This paper examines the theoretical and empirical properties of a supervised factor model based on combining forecasts using principal components (CFPC), in comparison with two other supervised factor models (partial least squares regression, PLS, and principal covariate regression, PCovR) and with the unsupervised principal component regression, PCR. The supervision refers to training the predictors for a variable to forecast. We compare the performance of the three supervised factor models and the unsupervised factor model in forecasting of U.S. CPI inflation. The main finding is that the predictive ability of the supervised factor models is much better than the unsupervised factor model. The computation of the factors can be doubly supervised together with variable selection, which can further improve the forecasting performance of the supervised factor models. Among the three supervised factor models, the CFPC best performs and is also most stable. While PCovR also performs well and is stable, the performance of PLS is less stable over different out-of-sample forecasting periods. The effect of supervision gets even larger as forecast horizon increases. Supervision helps to reduce the number of factors and lags needed in modelling economic structure, achieving more parsimony.  相似文献   

20.
The Asymptotics of MM-Estimators for Linear Regression with Fixed Designs   总被引:1,自引:0,他引:1  
MM-estimators achieve simultaneous high efficiency and high breakdown point over contamination neighborhoods. Inference based on these estimators relies on their asymptotic properties, which have been studied for the case of random covariates. In this paper we show that, under relatively mild regularity conditions, MM-estimators for linear regression models are strongly consistent when the design is fixed. Moreover, their strong consistency allows us to show that these estimators are also asymptotically normal for non-random covariates. These results justify the use of a normal approximation to the finite-sample distribution of MM-estimators for linear regression with fixed explanatory variables. Additionally, these results have been used to extend the robust bootstrap (Salibian-Barrera and Zamar in Ann Stat 30:556–582, 2002) to the case of fixed designs [see Salibian-Barrera 2004, submitted].Research supported by an NSERC Research Grant (Individual)  相似文献   

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