Efficiency loss in a Cournot oligopoly with convex market demand

We consider a Cournot oligopoly model where multiple suppliers (oligopolists) compete by choosing quantities. We compare the social welfare achieved at a Cournot equilibrium to the maximum possible, for the case where the inverse market demand function is convex. We establish a lower bound on the efficiency of Cournot equilibria in terms of a scalar parameter derived from the inverse demand function, namely, the ratio of the slope of the inverse demand function at the Cournot equilibrium to the average slope of the inverse demand function between the Cournot equilibrium and a social optimum. Also, for the case of a single, monopolistic, profit maximizing supplier, or of multiple suppliers who collude to maximize their total profit, we establish a similar but tighter lower bound on the efficiency of the resulting output. Our results provide nontrivial quantitative bounds on the loss of social welfare for several convex inverse demand functions that appear in the economics literature.     

Mixed oligopoly and spatial price discrimination with foreign firms

This paper is the first to examine the welfare consequences of foreign competition in a mixed oligopoly set in a linear model of spatial price discrimination. It demonstrates that the entry of a foreign firm often lowers domestic welfare. This results because the public firm locates largely independently of the presence of the foreign firm and because the profit earned by the foreign firm reduces domestic welfare. Privatization of the public firm typically lowers domestic welfare but can increase global welfare. Thus, domestic governments are unlikely to allow foreign entry and when they do, they are unlikely to privatize the public firm despite the potential rise in global welfare.     

Feedback equilibria in a dynamic renewable resource oligopoly: Pre-emption,voracity and exhaustion

We revisit a recent literature on productive asset exploitation describing a differential oligopoly game of resource extraction under static, linear feedback and nonlinear feedback strategies, where we explicitly allow for the possibility of resource exhaustion. We show that (i) feedback rules entail resource exhaustion for a finite number of firms; and (ii) feedback strategies are more aggressive than static ones as long as the resource stock is large enough, in accordance with the acquired view based on the traditional pre-emption argument associated with feedback information.     

基于模糊组合权的模糊TOPSIS方法在供应商选择中的应用研究

供应商的选择在供应链管理中是很重要环节,供应商选择的成功与否将直接影响到整个供应链的竞争优势,故有必要对供应商选择进行深入研究。本文将已有的模糊组合权方法和模糊TOPSIS方法相结合,提出一种基于模糊组合权的模糊TOPSIS方法,并将其应用于供应商的选择研究中。文章首先总结已有的相关研究结果,给出供应商评价的准则,接着介绍三角模糊数的相关理论,推出模糊组合权及模糊TOPSIS的算法步骤,最后通过一个算例验证方法的可行性。     

-learning agents in a Cournot oligopoly model

Q-learning is a reinforcement learning model from the field of artificial intelligence. We study the use of Q-learning for modeling the learning behavior of firms in repeated Cournot oligopoly games. Based on computer simulations, we show that Q-learning firms generally learn to collude with each other, although full collusion usually does not emerge. We also present some analytical results. These results provide insight into the underlying mechanism that causes collusive behavior to emerge. Q-learning is one of the few learning models available that can explain the emergence of collusive behavior in settings in which there is no punishment mechanism and no possibility for explicit communication between firms.     

Efficiency and information aggregation in auctions with costly information

Consider an auction in which k identical objects are sold to n > k bidders who each have a value for one object which can have both private and common components to it. Private information concerning the common component of the object is not exogenously given, but rather endogenous and bidders face a cost to becoming informed. If the cost of information is not prohibitively high, then the equilibrium price in a uniform price auction will not aggregate private information, in contrast to the costless information case. Moreover, for a wide class of auctions if the cost of information is not prohibitively high then the objects can only be allocated in a weakly efficient sense, and then only if the equilibrium proportion of endogenously informed agents is vanishing as the economy grows. In spite of these results, it is shown that there is a mechanism for which there exist equilibria and for which (weak) efficiency is achieved as the economy grows in the face of endogenous information acquisition.Received: 6 August 2001, Accepted: 27 July 2002, JEL Classification: C72, D44, D82Financial support under NSF grant SBR-9507912 is gratefully acknowledged. I thank Valentina Bali for conversations out of which this project grew, and Larry Ausubel for a very helpful discussion of an early version of this paper at the 1998 summer meetings of the Econometric Society from which I have borrowed in structuring the exposition of the paper. I also thank Andy Postlewaite, Jeroen Swinkels, and an associate editor and anonymous referee for helpful comments and suggestions on earlier drafts.     

基于XML与本体的异构数据源的集成解决方案

文章针对“信息孤岛”问题,就现有的解决方案从企业和技术角度进行了分类及比较分析,最后提出了一个基于XML与本体的异构数据源的集成解决方案,并对该解决方案的优缺点进行了分析。     

Evolutionary competition in a mixed market with socially concerned firms

In this paper we study an oligopoly market where profit-maximizing firms and socially concerned firms compete in quantities. Confronting remarks by Milton Friedman and Gary Becker, we are using an evolutionary setting to investigate the endogenous choice of the proper objective of business firms and the influence of product differentiation on the long run survival of firms which pursue non-profit motives. We find that firms which consider a combination of profit and consumer welfare can indeed have larger market shares and profits than their profit-maximizing rivals. One insight is that it might pay off for shareholders to consider stakeholder welfare, but that the level of social concern should not be too high. Based on a strategy׳s profitability, we consider asynchronous evolutionary updating with firms selecting Nash quantities or choosing best replies to the expected market quantity. Here we observe that the consumers׳ willingness to pay a price premium for products is crucial for the long run survival of socially concerned firms. Depending on the degrees of product differentiation and social concern, long run outcomes consist either of both types of firms or only one type of firm. If the firms׳ propensity to switch between a social or a profit-maximizing strategy is sufficiently large, steady states are unstable and even complicated dynamics can occur.     

Bi-criteria solid transportation problem with substitutable and damageable items in disaster response operations on fuzzy rough environment

Successful planning and scheduling of relief operations play a key role in saving lives and reducing damage in disasters. These disaster operations involve a variety of challenging multi-objective optimization problems, for which soft computing methods are well suited. In this investigation, relief materials and human resources are transported from some distribution centers (DCs) to some delivery points (DPs) through conveyances. The objectives are to minimize both total cost and time for transportation. Some particular models for (a) substitutable items (b) damageable items and (c) safety Factor have been derived. To convert bi-criteria solid transportation problem into a single objective problem, three different techniques (i) Fuzzy interactive satisficing method, (ii) Global Criterion Method and (iii) Convex Combination Method are used. Then the reduced single objective problem is solved by a non-linear optimization technique – Generalized reduced gradient method using LINGO-14.0. The models are illustrated through some numerical examples and optimal results are presented in tabular forms.     

多数据源数据信息交换中间件的设计与实现

网络环境下的异构数据交换技术是数据集成、电子商务应用和Web服务合成系统等实际应用的核心支撑技术。文章基于"协作者"模式,以关系数据库和XML文档为异构数据源的典型代表,给出了Web服务环境下的数据交换模型,介绍了数据交换模型的4种基本操作的算法思想和利用Web服务合成技术实现数据交换的方法,通过一个示例,验证了文章提出的数据交换方法的有效性。     

Assessment of development regions for financial support allocation with fuzzy decision making: A case of Turkey

European Union is a project focused on the balanced distribution of the prosperity, established by the common market, to all regions. For this purpose, in order to collect comparable statistics, socio-economic zones have been established within the framework of certain criteria using the classification of Nomenclature of Territorial Units for Statistics (NUTS). These regions are formed in 3 levels, based on the countries that are members and candidates for membership. Supports provided within the framework of the EU in order to reduce regional socio-economic disparities and to ensure regional development are being made and measured on the basis of regions (development zones) established with Level 2 NUTS. As a candidate country to the EU, Turkey also tries to achieve harmonization and regional development through Instrument for Pre-Accession Assistance (IPA). In this study, the extent to which the development regions identified in the Turkish scale should benefit from such supports is assessed on the basis of specific criteria. How to distribute IPA support, which is a limited resource, to the regions according to framework agreements and regional development goals is a complex issue. In order to solve this problem, development zones are evaluated using two different Multi Criteria Decision Making methods: Fuzzy-PROMETHEE and Fuzzy-MULTIMOORA. As a result, a framework to provide specific distribution of funds to support regional development and to show the weaknesses of these regions is presented.     

A fuzzy group decision-making approach in quality function deployment

Quality function deployment (QFD) is comprised of two major group decision-making processes. One is to collect the customer requirements from a group of customers, whereas the other is to determine the relationship between customer requirements and technical measures by a cross-functional team. Generally, different and/or even subjective opinions are quite often in a group decision-making process due to the limitations of experience and impreciseness. Obviously, the importance of each customer requirement and the relationship between customer requirements and technical measures are determined by a group of people with imprecision and vagueness. Under such circumstances, a fuzzy group decision-making approach can be applied in QFD to deal with a group decision-making process when the information is imprecise and fuzzy. Moreover, an example is provided as well as the computational steps to show this fuzzy group decision-making approach can be effectively used in QFD to make decisions with imprecision and vagueness.     

Investigating the satisfaction of citizens in municipality services using fuzzy modelling

Rapid developments in communication and information technologies in the world force local administrators to be more effective. For a local administrator to be elected again, satisfaction of citizens with the duties that need to be performed and the services provided is significant. In this study, citizen satisfaction with municipality services was measured using a questionnaire on a household level. It was aimed to develop a new approach in evaluation of municipal service quality.The data that were obtained were analyzed with fuzzy multi-criteria decision-making techniques. For determination of criterion weights, FDEMATEL was utilized, and for household-based ranking, the FTOPSIS technique was implemented. A raster map was created in the ArcGIS geostatistics module by applying IDW interpolation on the resulting values. The map that was produced visually revealed the satisfaction of citizens regarding the quality of municipality services based on location. When the map was analyzed, it was seen that the satisfaction levels in the study areas of two neighborhoods were high, while the levels in the study area of one neighborhood was low.     

Integrated environmental assessment of the location selection with fuzzy analytical network process

Owing to the complexity of a construction project, the fuzzy ANP is helpful to deal with interdependent relationships within a multi-criteria decision-making model. This paper uses the Porter’s diamond model that influences how competitive advantages, which is a matrix providing a conceptual model for the main framework, as a construct for selecting the location of a regional hospital in Taiwan to determine its effectiveness. The applicability of our proposed fuzzy ANP model is demonstrated with a case study that summarizes an intervention in which the model’s framework and basic concepts were applied.     

Controlled information destruction: the final frontier in preserving information security for every organisation

Information security represents the cornerstone of every data processing system that resides in an organisation’s trusted network, implementing all necessary protocols, mechanisms and policies to be one step ahead of possible threats. Starting from the need to strengthen the set of security services, in this article we introduce a new and innovative process named controlled information destruction (CID) that is meant to secure sensitive data that are no longer needed for the organisation’s future purposes but would be very damaging if revealed. The disposal of this type of data has to be controlled carefully in order to delete not only the information itself but also all its splinters spread throughout the network, thus denying any possibility of recovering the information after its alleged destruction. This process leads to a modified model of information assurance and also reconfigures the architecture of any information security management system. The scheme we envisioned relies on a reshaped information lifecycle, which reveals the impact of the CID procedure directly upon the information states.     

Equilibrium existence in Tullock contests with incomplete information

We prove an existence theorem for pure strategy Bayesian Nash equilibrium in Tullock contests where the information endowment of each contender is described by a countable partition.     

Irreversible investment and R&D spillovers in a dynamic duopoly

Investments in new production processes usually involve a significant amount of R&D, generating spillovers that lowers the second comer's investment cost. We show that these spillovers substantially affect the equilibrium of the dynamic game. Even for low spillover values, the leader delays her investment until the stochastic fundamental has gone past the level such that the follower's optimal strategy is to invest as soon as he attains the spillover. This bears several interesting implications. First, because the follower invests as he benefits from the spillover, in equilibrium the average time delay between the two investments is short, as it should be expected. Second, in case of a major innovation, an optimal public policy requires an intervention in favor of the investment activity; an increase in uncertainty - delaying the equilibrium - calls for higher subsidization rates. Third, numerical simulations show that the spillover reduces the difference between the leader's and the follower's maximum value functions. Accordingly, our model can help generate realistic market betas.     

A note on consistency and unbiasedness of point estimation with fuzzy data

Based on the SLLN for fuzzy random variables in uniform metric d, some asymptotical properties of point estimation with fuzzy random samples are investigated. The results of this paper establish a corresponding version on the consistency and unbiasedness of point estimation with n-dimensional fuzzy samples under considering a kind of fuzzy statistic.     

GIS-based fuzzy multi-criteria approach for optimal site selection of fire stations in Istanbul,Turkey

Fire stations play a central role in protection and response activities as part of emergency management services in cases of fire incidences. With the rising urban populations and city expansions, the demand for more fire services resultantly increases. It then becomes critical to effectively plan the location of emergency facilities to adequately service the population and ensure the protection of lives and infrastructure. This study, therefore proposes the use of the fuzzy extension of the Multi-Criteria Decision-Making (MCDM) method of Analytical Hierarchical Process (AHP), hence called fuzzy AHP, integrated with Geographic Information Systems (GIS) approach to optimally site new fire stations for the case of Istanbul region. This proposed fuzzy approach simulates the subjective expert judgements for the preferences of the six criteria assessed for fire station suitability mapping and thereby accounted for the uncertainty of crisp comparison values via triangular fuzzy numbers (TFNs). The criteria weights evaluated from this procedure were used in a weighted overlay analysis of the reclassified criteria map layers in ArcGIS to generate a fire station suitability map. These resultant fuzzy AHP criteria weights were validated using another MCDM technique, called Best-Worst Method (BWM) and found to be comparable and consistent. The criteria that had the strongest influence on the selection of sites for fire stations were identified to be: the density of hazardous material facilities (DHM), a high population density (HPD) and proximity to main roads (PMR) with associated weights of 33.3%, 24.4% and 15.2%, respectively. Based on a thorough assessment within the areas represented by class values ranging from 3 to 5 on the suitability map, a total of 34 new fire station sites were selected complementing the existing 121 fire stations. Further, a prioritization analysis from low, medium to high, was performed to plan the phases for the construction of new fire stations in view of competing budgetary needs and resource constraints. The methodology to achieve this was proposed and modelled for enhancing the decision-making process in urban fire station site selection studies.     

网络环境下的水利信息服务

网络的充分发展,使信息资源出现了许多新的特点,为信息服务提供了一个新的服务环境,水利信息服务必须充分利用网络技术与网络信息资源,开展各种形式的水利信息服务。