Market share dynamics in a duopoly model with word-of-mouth communication

We analyze dynamic price competition in a homogeneous goods duopoly, where consumers exchange information via word-of-mouth communication. A fraction of consumers, who do not learn any new information, remain locked-in at their previous supplier in each period. We analyze Markov perfect equilibria in which firms use mixed pricing strategies. Market share dynamics are driven by the endogenous price dispersion. Depending on the parameters, we obtain different ‘classes’ of dynamics. When firms are impatient, there is a tendency towards equal market shares. When firms are patient, there are extended intervals of market dominance, interrupted by sudden changes in the leadership position.     

The dynamics of a banking duopoly with capital regulations

This paper analyses the dynamics of a banking duopoly game with heterogeneous and homogeneous players (as regards the type of expectations' formation), to investigate the effects of the capital requirements introduced by international accords (Basel-I in 1988 and more recently Basel-II and Basel-III), in the context of the Monti-Klein model. This analysis reveals that the policy of introducing a capital requirement tends to stabilise the market equilibrium (both with heterogeneous and homogeneous banks). Moreover, it is shown that 1) when the capital standard is reduced the market stability is lost through a flip bifurcation and subsequently a cascade of flip bifurcations may lead to periodic cycles and chaos; 2) when the expectations are heterogeneous even the case of multi-stability may be present.Therefore, although on the one side the capital regulation is harmful for the equilibrium loans' volume and profit, on the other side it is effective in keeping or restoring the stability of the Cournot–Nash equilibrium in the banking duopoly.     

Evolutionarily stable conjectures and other regarding preferences in duopoly games

We study the evolutionary selection of conjectures in duopoly games when players have other regarding preferences, i.e. preferences over payoff distributions. In both the Cournot and Bertrand duopoly games, the consistent conjectures are independent of other regarding preferences. Both duopoly games have evolutionarily stable conjectures that depend on other regarding preferences but that do not coincide with the consistent conjectures. For increasingly spiteful preferences, the evolutionarily stable conjectures implicate low quantities in the Cournot game and high prices in the Bertrand game, whereas the inverse relationships hold for the consistent conjectures. We discuss our findings in the context of ultimate and proximate causation.     

The dynamics of a differentiated duopoly with quantity competition

We analyse the dynamics of a Cournot duopoly with heterogeneous players to investigate the effects of micro-founded differentiated products demand on stability. The present study, which indeed modifies and extends Zhang et al. (2007) (Zhang, J., Da, Q., Wang, Y., 2007. Analysis of nonlinear duopoly game with heterogeneous players. Economic Modelling 24, 138–148) and Tramontana, F., (2010) (Tramontana, F., 2010. Heterogeneous duopoly with isoelastic demand function. Economic Modelling 27, 350–357), reveals that a higher degree of product differentiation may destabilise the market equilibrium. Moreover, we show that a cascade of flip bifurcations may lead to periodic cycles and ultimately chaotic behaviours. Since a higher degree of product differentiation implies weaker competition, then a theoretical implication of our findings, that also constitute a policy warning, is that a fiercer (weaker) competition tends to stabilise (destabilise) the unique positive Cournot–Nash equilibrium.     

Analysis on the Strategy Choice of Market Share and Customer Share

Along with much attention increasingly to the customer share, the lifetime value of the customer and the customer loyalty become more and more important as the key factors for the perpetual development of business enterprises. This paper did a certain analysis on the comparative advantage of the customer share, and probed into the different strategy choice of business enterprises on each development stage, hoping to supply some suggestions on certain degree as reference value.     

The core of some location games

An important problem in Location Theory is that of assigning plants to locations in an optimal manner. In the context of this problem, recognizing interplant transportation costs, Koopmans and Beckmann (1957) introduced the Quadratic Assignment Problem (QAP). It is shown in this paper that when the QAP is formulated as a cooperative location game, its core may be empty. By contrast, the core of the game corresponding to thelinear assignment problem (where transportation costs are disregarded) is assured to be non-empty. Some conditions under which the core is non-empty are discussed.I am grateful to two anonymous referees of this journal for their comments.     

The Semi-Strong Efficiency of the Australian Share Market*

This paper tests the weak and semi-strong forms of the Efficient-Markets Hypothesis (EMH) using data on the Australian skate market in the 1980s. The tests are based on aggregate share price indexes and the semi-strong efficiency tests use macroeconomic data The weak-form tests examine the autocorrelation structure of share returns and test for unit roots in share prices. The data are found to be consistent with the EMH.     

控股系数与股票市场监管

为保护中小额投资者的利益，及时地发现股票市场的操纵行为并动态监控相关账户，是当前股票动态技术监管的迫切要求。利用有效交易信息与股份分布状况构造控股系数，可使市场监管人员进行事前监管和事中监督，使动态技术监管更富有操作性。     

Global environment and dynamic games of environmental policy in an international duopoly

This paper examines a differential game model of international pollution control in which polluting oligopolists compete in a third country market. Two alternative policy instruments (emission taxes and command-and-control regulations) are considered. A tougher emission policy in the home country enhances the foreign firm’s competitiveness because of the static “rent-shifting” effect. The foreign country also enjoys a future improvement of the global environmental quality by “free riding” on the home country’s emission reduction effort. Because of these strategic effects, the levels of environmental policy determined in the noncooperative policy game are distorted away from the socially optimal level. Moreover, the emission tax game produces a more distortionary outcome than that in the command-and-control game; it generates more pollution and lower welfare.      

Market Share Quotas and Community Reinvestment

This notes explores some theoretical implications of the U.S. Department of Justice's policy requiring lenders to seek as much market share in protected neighborhoods as elsewhere. In the asymmetric Cournot case, the high-cost lender in the protected neighborhood responds in the expected way, but the low-cost lender's response depends on the curvature of the demand function. For concave demand, the low-cost lender's output decisions run counter to those of the high-cost lender, undermining the policy's effectiveness and inefficiently shifting production in the protected market from the low-cost provider to the high-cost provider.     

Stable games and their dynamics

We study a class of population games called stable games. These games are characterized by self-defeating externalities: when agents revise their strategies, the improvements in the payoffs of strategies to which revising agents are switching are always exceeded by the improvements in the payoffs of strategies which revising agents are abandoning. We prove that the set of Nash equilibria of a stable game is globally asymptotically stable under a wide range of evolutionary dynamics. Convergence results for stable games are not as general as those for potential games: in addition to monotonicity of the dynamics, integrability of the agents' revision protocols plays a key role.     

The convergence of equilibrium strategies of approximating signaling games

Summary For a class of infinite signaling games, the perfect Bayesian equilibrium strategies of finite approximating games converge to equilibrium strategies of the infinite game. This proves the existence of perfect Bayesian equilibrium for that class of games. It is well known that in general, equilibria may not exist in infinite signaling games.I am very grateful to Karl Iorio with whom I derived most of the results in this paper. I am solely responsible for any remaining errors. I am also grateful to Robert Anderson, Debra Aron, Eddie Dekel, Raymond Deneckere, Michael Kirscheneiter, Steven Matthews, Roger Myerson, Daniel Vincent and Robert Weber for comments on previous drafts of this paper.     

Non-computable strategies and discounted repeated games

Summary A number of authors have used formal models of computation to capture the idea of bounded rationality in repeated games. Most of this literature has used computability by a finite automaton as the standard. A conceptual difficulty with this standard is that the decision problem is not closed. That is, for every strategy implementable by an automaton, there is some best response implementable by an automaton, but there may not exist any algorithm forfinding such a best response that can be implemented by an automaton. However, such algorithms can always be implemented by a Turing machine, the most powerful formal model of computation. In this paper, we investigate whether the decision problem can be closed by adopting Turing machines as the standard of computability. The answer we offer is negative. Indeed, for a large class of discounted repeated games (including the repeated Prisoner's Dilemma) there exist strategies implementable by a Turing machine for whichno best response is implementable by a Turing machine.The work was begun while Nachbar was a visitor at The Center for Mathematical studies in Economics and Management Science at Northwestern University; he is grateful for their hospitality. We are also grateful to Robert Anderson and Neil Gretsky and to seminar audiences at UCLA for useful comments, and to the National Science Foundation and the UCLA Academic Senate Committee on Research for financial support. This paper is an outgrowth of work reported in Learning and Computability in Discounted Supergames.     

The strategy structure of some coalition formation games

In coalitional games with side payments, the core predicts which coalitions form and how benefits are shared. The predictions however run into difficulties if the core is empty or if some coalitions benefit from not blocking truthfully. These difficulties are analyzed in games in which an a priori given collection of coalitions can form, as the collection of pairs of buyer–seller in an assignment game. The incentive properties of the core and of its selections are investigated in function of the collection. Furthermore the relationships with Vickrey–Clarke–Groves mechanisms are drawn.     

战略性经营者激励选择与国际市场份额竞争

本文首先用具有线性需求和规模收益不变生产技术的Cournot双头模型来刻画国际市场份额竞争。指出 ,如果参与国际竞争的本国企业是所有权与经营权分离的企业 ,那么 ,无论竞争对手是否是所有权与经营权分离的企业 ,本国企业所有者总是有积极性操纵经营者的激励 ,特别的 ,在只有本国企业作出单边激励选择的情况下 ,这种操纵可以使本国企业生产Stackelberg领先者产量成为可以置信的承诺。它在这里所起到的作用是与出口补贴在战略性贸易政策分析中所起到的作用相一致的。如果考虑到从过去的GATT到现在的WTO都规定政府不得以任何形式参与国际竞争 ,这个结论就更有趣了。因为无须政府帮助 ,本国企业所有者凭借自身的力量就能实现有利于本国企业的竞争结果。这种民间对政府的替代是有意义的。在双边激励选择的情况下 ,两国企业陷入了“囚徒困境”。本国企业只有诉诸于本国政府对国际市场的干预 ,才能重新获得Stackelberg领先者的地位 ;但与对它的传统理解相比 ,这种地位已然弱化。最后 ,我们还证明 ,根据相当一般的条件 ,所有者决定的最优经营者激励只与竞争类型 (数量竞争还是价格竞争 )有关 ,而与企业的产品类型 (替代品还是互补品 )无关。     

后危机时代下的市场共享与区域经济差距

分权式改革带来的非一体化市场逐渐表现出对经济发展的阻碍作用.尤其是危机爆发凸显区域专业化与风险分散之间的矛盾.本文着重从一体化市场的风险分担机制角度分析区域经济差距缩小的途径.研究表明,高度专业化的区域经济在更广阔的区域市场中能够有效规避风险,充分发挥溢出效应,促进区域经济收敛.在俱乐部趋同存在的条件下,东部地区受专业化和外资水平影响较大,中西部落后地区经济增长更多依赖于人口聚集和一体化市场下的溢出效应.     

A generalized framework for endogenous timing in duopoly games and an application to price-quantity competition

This paper extends the analysis of duopoly market by distinguishing two types of competition: (i) the basic form of competition where each firm is unrestricted in its choice of price and quantity and (ii) the non-basic form of competition where firms’ strategic choices over price and quantity are limited a priori. Our analysis focuses on the former rather than the latter. Under a very general setting of concave industrial revenue and asymmetric convex costs, we show that each firm typically makes more profit in the subgame perfect Nash equilibrium (SPNE) of the leader-follower price-quantity competition, one of the basic competition forms, than in the SPNE of the leader-follower price competition and that each firm always makes more profit under simultaneous move price-quantity competition than under simultaneous move price competition. We establish a generalized framework for endogenous timing in duopoly games which is capable of embodying and overcoming the inconsistency across the existing three frameworks in the field. We highlight the advantages of a 3-period general framework.     

Profitability of price and quantity strategies in a duopoly with vertical product differentiation

Using a model according to Mussa and Rosen (1978) and Bonanno and Haworth (1998) we consider a sub-game perfect equilibrium of a two-stage game in a duopolistic industry in which the products of the firms are vertically differentiated. In the industry, there are a high quality firm and a low quality firm. In the first stage of the game, the firms choose their strategic variables, price or quantity. In the second stage, they determine the levels of their strategic variables. We will show that, under an assumption about distribution of consumers' preference, we obtain the result that is similar to Singh and Vives (1984)' proposition (their Proposition 3) in the case of substitutes with nonlinear demand functions. That is, in the first stage of the game, a quantity strategy dominates a price strategy for both firms. Received: April 23, 1999; revised version: May 31, 2000     

Market games with asymmetric information: the core

This paper concerns cores of economies with asymmetric information. Alternative definitions of the information available to traders in coalitions and the cooperative games they generate are analyzed. An important technical result states that such NTU games in characteristic function form are well defined. Properties of various cores with asymmetric information are examined. Sufficient conditions on information sharing rules are provided for the induced games to be totally balanced or balanced, so that their cores are nonempty. Incentive compatibility issues are considered. Finally, a perspective on this research area is provided.     

金融市场分割的成因及效率:信托视角的透析

货币市场与资本市场的长期隔离,造成了资本要素配置效率的损失,究其原因在于资本流动、配置的制度约束,信托制度的不健全,阻碍了信托业的发展,加剧了货币市场与资本市场的隔离程度。通过建立理论模型说明了这一点,并提出政策建议。