Admissibility in Games1

Suppose that each player in a game is rational, each player thinks the other players are rational, and so on. Also, suppose that rationality is taken to incorporate an admissibility requirement—that is, the avoidance of weakly dominated strategies. Which strategies can be played? We provide an epistemic framework in which to address this question. Specifically, we formulate conditions of rationality and mth‐order assumption of rationality (RmAR) and rationality and common assumption of rationality (RCAR). We show that (i) RCAR is characterized by a solution concept we call a “self‐admissible set”; (ii) in a “complete” type structure, RmAR is characterized by the set of strategies that survive m+1 rounds of elimination of inadmissible strategies; (iii) under certain conditions, RCAR is impossible in a complete structure.     

基于自由处置性的网络系统效率评价模型研究

网络系统生产可能集是构建网络DEA模型的基础,而相邻生产子过程的投入产出连接条件则是构造生产可能集的关键。现有的网络DEA模型在本质上都假设所有子过程的投入产出都满足强自由处置性,然而在实际生产管理活动中,这一假设未必成立。本文从各类自由处置公理出发,系统地研究了各种类型的子过程投入产出连接条件,构建了一般网络系统的生产可能集,给出了相应的等价形式,并构建了相应的网络DEA模型用于评价决策单元的效率。最后利用本文提出的方法和模型对我国上市银行的效率进行了评价。本文的研究对于一般网络系统的绩效评价和改进具有重要的意义。     

Replenishment Policies for Multi‐Product Stochastic Inventory Systems with Correlated Demand and Joint‐Replenishment Costs

This study analyzes optimal replenishment policies that minimize expected discounted cost of multi‐product stochastic inventory systems. The distinguishing feature of the multi‐product inventory system that we analyze is the existence of correlated demand and joint‐replenishment costs across multiple products. Our objective is to understand the structure of the optimal policy and use this structure to construct a heuristic method that can solve problems set in real‐world sizes/dimensions. Using an MDP formulation we first compute the optimal policy. The optimal policy can only be computed for problems with a small number of product types due to the curse of dimensionality. Hence, using the insight gained from the optimal policy, we propose a class of policies that captures the impact of demand correlation on the structure of the optimal policy. We call this class (s, c, d, S)‐policies, and also develop an algorithm to compute good policies in this class, for large multi‐product problems. Finally using an exhaustive set of computational examples we show that policies in this class very closely approximate the optimal policy and can outperform policies analyzed in prior literature which assume independent demand. We have also included examples that illustrate performance under the average cost objective.     

汇率的非线性组合预测方法研究

近年来的经济统计研究表明,组合预测比单项预测具有更高的预测精度,但线性组合预测方法在汇率的组合建模与预测方面存在着较大的局限性。本文提出了一种基于模糊神经网络的汇率非线性组合建模与预测新方法,并给出了相应的混合学习算法。对于英镑、法朗、瑞士法朗、日本元对美元等汇率时间序列的组合建模与预测结果表明,该方法具有很强的学习与泛化能力,在处理外汇市场这种具有一定程度不确定性的非线性系统的组合建模与预测方面有很好的应用价值。     

Sharp Identification Regions in Models With Convex Moment Predictions

We provide a tractable characterization of the sharp identification region of the parameter vector θ in a broad class of incomplete econometric models. Models in this class have set‐valued predictions that yield a convex set of conditional or unconditional moments for the observable model variables. In short, we call these models with convex moment predictions. Examples include static, simultaneous‐move finite games of complete and incomplete information in the presence of multiple equilibria; best linear predictors with interval outcome and covariate data; and random utility models of multinomial choice in the presence of interval regressors data. Given a candidate value for θ, we establish that the convex set of moments yielded by the model predictions can be represented as the Aumann expectation of a properly defined random set. The sharp identification region of θ, denoted Θ_I, can then be obtained as the set of minimizers of the distance from a properly specified vector of moments of random variables to this Aumann expectation. Algorithms in convex programming can be exploited to efficiently verify whether a candidate θ is in Θ_I. We use examples analyzed in the literature to illustrate the gains in identification and computational tractability afforded by our method.     

基于粗糙集理论-神经网络-蜂群算法集成的客户流失研究

针对电信客户流失问题的复杂性,融合粗糙集理论、神经网络和蜂群算法的优势,提出了一种新的客户流失预测模型——基于粗糙集理论、神经网络和蜂群算法线性集成多分类器的客户流失预测模型。首先利用自组织神经网络(SOM)对连续属性值进行非监督离散化处理;接着使用粗糙集方法(RS)对离散属性进行约简;然后分别使用BP神经网络、RBF神经网络、ELMAN神经网络和广义回归神经网络(GRNN)在约简属性集上建立4个子分类器;最后使用模型集成法对4个子分类器进行线性集成,并采用人工蜂群(ABC)算法优化线性组合的权重。将该模型应用于某电信客户流失,实验结果表明该集成方法是可行且有效的。     

Linear programming approach to solve interval-valued matrix games

Matrix game theory is concerned with how two players make decisions when they are faced with known exact payoffs. The aim of this paper is to develop a simple and an effective linear programming method for solving matrix games in which the payoffs are expressed with intervals. Because the payoffs of the matrix game are intervals, the value of the matrix game is an interval as well. Based on the definition of the value for matrix games, the value of the matrix game may be regarded as a function of values in the payoff intervals, which is proven to be non-decreasing. A pair of auxiliary linear programming models is formulated to obtain the upper bound and the lower bound of the value of the interval-valued matrix game by using the upper bounds and the lower bounds of the payoff intervals, respectively. By the duality theorem of linear programming, it is proven that two players have the identical interval-type value of the interval-valued matrix game. Also it is proven that the linear programming models and method proposed in this paper extend those of the classical matrix games. The linear programming method proposed in this paper is demonstrated with a real investment decision example and compared with other similar methods to show the validity, applicability and superiority.     

变精度优势粗糙集属性约简择优算法

以从多个粗糙集属性约简中选择最优的约简为目的,分析了作为度量工具的现有条件信息熵在应用过程中的缺陷.借鉴变精度粗糙集理论的思想,在对阈值参数进行二次选择的基础上,提出一种新的条件信息熵.基于新的条件信息熵设计了一种变精度优势粗糙集属性约简的择优算法,克服了现有条件信息熵的不足.理论分析和实践结果均表明了所设计算法的有效性.     

LF可数F紧空间的若干特征性质

本文对Ｌ－ｆｕｚｚｙ可数Ｆ紧空间进行了探讨，给出了它的一些特征性质，研究了它与其它Ｆ紧空间的关系。     

基于粗集理论的线性回归方法及实证分析

通过分析实际问题中经济变量间往往出现多重共线性的现象,将粗集理论的约简思想引入线性回归分析,提出了基于粗集理论的线性回归模型来解决多重共线性问题,并通过实证分析来验证模型的可行性,为人们进行科学的预测和决策提供了一种新的思想和方法。