管理理论战略竞争策略博弈论1

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1、企业管理中的竞争问题董志勇 博士 副教授中国人民大学经济学院职业经理人资格中国最具价值的三大证书之一 CCMC与企业管理1个人简介-中国人民大学经济学院院长助理 副教授 经济学博士-2008年北京奥运会特许商品调查委员会首席专家-2008年北京奥运会旅游纪念品调查研究首席专家-欧美同学会会员（1998年）-中国宝鸡外国语学院客座教授(1999年)-新加坡华夏学院学术委员会委员(2001年)-欧洲维多利亚大学客座教授（2002年）-亚洲发展银行青年组专家(Young Economist of ADB)（2002年）-清华大学继续教育学院客座教授（2003年）-吉林电力高级经济顾问（2002年）-

2、吉林白城市人民政府经济顾问（2003年）-国联股份高级顾问（2003年）-中国人民大学侨联副主席（2004年）-中国井冈山干部学院兼职教授（2005年）2博弈论和策略行为Game Theory&Strategic Behaviors3Lecture Plan/本讲计划nGame Theory nStrategy&Payoff Matrix nDominant&Dominated Strategies nNash EquilibriumnMaximin Strategy&Mixed Strategy nStrategic Behavior 4Elements of a GameGame has

3、the following elements:Players:who is involved?Rules:who moves when?What do they know when they move?What can they do?Outcomes:for each possible set of actions by the layers,which is the outcome of the gamePayoffs:what are the players preferences over the possible outcome?5Strategy&Payoffsn博弈论把人间一切竞

4、争活动看成是玩策略游戏。这种策略游戏是在一定的游戏规则之下进行n它的两个最基本的概念是策略与支付矩阵n一种策略(Strategy)表示游戏参与者的一套运作计划和手段。如“降价15%”就是一种策略n收益矩阵(Payoff matrix)是表示游戏参与者在各种不同策略下的利润额的一套支付表格n寡头垄断，尤其是双寡头垄断竞争，特别适合使用博弈论研究6Strategy&PayoffsnPrisoners Dilemma(囚犯两难)n两个嫌犯被捕并受到指控，但除非至少一人招供犯罪，警方并无充分证据将其按罪判刑n警方将他们分开审讯（不能沟通），并对他们说明不同行动带来的后果。n如果二人都不坦白，只能判简单

5、刑事罪，坐牢1个月n如果二人都坦白，两人都会定罪，判刑六个月；n如果其中一个坦白，另一个不坦白；那么坦白者马上释放（从宽）、不坦白者将会判刑九个月。n请问两个嫌犯该怎么办？7Strategy&PayoffsnPrisoners Dilemma(囚犯两难)n策略(Strategy):“沉默”&“招认”n收益矩阵(Payoff Matrix)如下：囚犯2沉默招认囚犯1沉默-1，-1-9，0招认0，-9-6，-68Strategy&PayoffsnPrisoners Dilemma(囚犯两难)n囚犯两难的问题在现实中常常出现。n比如两家企业的价格战。企业B遵守协议违约降价企业A遵守协议100，100

6、30，130违约降价130，3070，709Strategy&Payoffsn性别战博弈(The Battle of Sex)n一男一女试图安排一个晚上的娱乐内容n选择（策略）：“歌剧”、“拳击”；不过男女有别n收益矩阵(Payoff Matrix)如下：男(The Man)歌剧拳击女(The Lady)歌剧2，10，0拳击0，01，21011Strategy&PayoffsnOther Examples nCoordination games nSmith and Jones are trying to decide whether to design the computers they

7、sell to use large or small floppy disks nBoth players will sell more computers if their disk drives are compatible.nStrategies:“Large”or“Small”nPayoffs are as follows.12Strategy&PayoffsnOther Examples nCoordination games:payoff matrixJonesLargeSmallSmithLarge2,2-1,-1Small-1，-11,113Dominant Strategie

8、s(支配策略)nWe say a player has a dominant strategy if it is the strictly best response to any strategies the other players might pick.nIn the analysis of any game,the first step is to determine if any player has a dominant strategy.nIf such a strategy exists,then the outcome of the game should be easil

9、y determined,since the player will use the dominant strategy and other players will subsequently adopt their best responses.nExamples:nDoes the Prisoners Dilemma have any dominant strategy?nHow about the Coordination Game?14Dominated Strategies(被支配策略)nA dominated strategy is an alternative that yiel

10、ds a lower payoff than some other strategy,no matter what the other players in the game do.nA rational player will never use a dominated strategy in the actual action of game playing.Hence it can be eliminated.nIt is clear that if the existence of a dominant strategy implies that all other choices a

11、re in fact the dominated strategies.nBut it is possible that there are dominated strategies,while there is no dominant strategy15Application:Iterative EliminationsnExample16Nash Equilibrium(纳什均衡)nEven though using a dominant strategy or a dominated strategy is a powerful simple way of“solving”a game

12、,this kind of game is usually an exception,instead of a norm.nWe must have a generic method of finding the solution(s)of a game.nSolution ConceptsnNash Equilibrium is the very first solution concept for non-cooperative games.17Nash Equilibrium(纳什均衡)nEssence of Nash EquilibriumnA Nash Equilibrium is

13、defined as a set of strategies such that non of the participants in the game can improve their payoff,given the strategies of the other participants.nNo one has a strictly incentive to deviate from the strategies in a Nash Equilibrium.18Nash Equilibrium(纳什均衡)nExample nConsider the following game.Is

14、there any dominant or dominated strategy?19Nash Equilibrium(纳什均衡)nProblem of Nash Equilibrium:nMultiple solutions!nExamples:nBattle of Sex nCoordination Game男(The Man)歌剧拳击女(The Lady)歌剧2，10，0拳击0，01，2JonesLargeSmallSmithLarge2,2-1,-1Small-1，-11,120Nash Equilibrium(纳什均衡)nProblem of Nash Equilibrium:nIn

15、sensitive to extreme payoffs(risks)nExample:Dangerous Coordination GameJonesLargeSmallSmithLarge2,2-1000,-1Small-1，-11,1In Practice,it is almost sure that Smith wants to“play safe”and never try“large”!21Nash Equilibrium(纳什均衡)nProblem of Nash Equilibrium:nNon-existence of pure strategy Nash Equilibri

16、umnExample:Match the PenniesnNo dominant strategy,no dominated strategy&no pure strategy Nash equilibrium as well!BHeadTailAHead1,-1-1,1Tail-1，11,-122Nash Equilibrium(纳什均衡)nMixed Strategies（混合策略）nA mixed strategy is a profile that specifies the probability of each pure strategy that is to be played.

17、nNash Theorem:nFor any game with finite number of pure strategies,there always exists a Nash Equilibrium in mixed strategy form.23Nash Equilibrium(纳什均衡)nMixed Strategies（混合策略）:ExamplesnCoordination GamenJones plays(Large,Small)according to(p,1-p)nSmiths expected payoffs are:n“Large”:2p+(-1)(1-p)=US(

18、L|(p,1-p)n“Small”:(-1)p+1(1-p)=US(S|(p,1-p)nSmith should be“indifferent”between the two choices nUS(L|(p,1-p)=US(S|(p,1-p)p=2/5 nHence Jones optimal mixed strategy must be(0.4,0.6)nExercise:find the optimal mixed strategy for Smith.nMatching the Pennies nFind the Nash equilibrium in mixed strategies

19、 242526Nash Equilibrium(纳什均衡)nNash Equilibrium 不一定有效率The Centipede Game(蜈蚣虫游戏):In this finite game of perfect information,there are two players,1 and 2.The players each start with 1 dollar in front of them.They alternate saying stop or continue,starting with player 1.When a player says continue,1 do

20、llar is taken by a referee from her pile and 2 dollars are put in her opponents pile.As soon as either player says stop,ply is terminated,and each player receives the money currently in her pile.Alternatively,play stops if both players piles reach 100 dollars.27Player 1Player 2Player 1Player 2Player

21、 1Player 2SCCCCCCSSSSS11032297100999998101100,10028Maxmin Strategies(最大最小策略)nWhen each player in the game will select the option that maximizes the minimum possible profit(or other desirable outcome),we say that the decision rule is a maxmin strategy.nThis may happen in situations when the market is

22、 highly competitive and decision makers are risk averse.nSo this is a useful case for managerial decision making.29 30迄今为止，对市场结构分析都以假定管理决策的中心是谋求最大利益。但是在如垄断寡头那样竞争十分激烈的场合，决策者可能采取一种风险厌恶政策，即确保在可能的最坏结果中得到最好的结果。也就是每个博弈者将在可能最少的利润方案中选择利润最大的方案。31（续）Nash 均衡为（3，6）和（6，3）企业1 最小32企业2 最小 3 2结果：双方都没有新产品推出 在这个例子中，Na

23、sh 不是小中取大解！32Maxmin Strategies(最大最小策略)nAnother example:33Sequential Game(顺序性博弈)顺序性博弈：先下弈的优势(First-mover Advantage)迄今为止，我们都隐含假定双方下弈者都是同时实施。在顺序(Sequential game)中，就是有先有后了。进入新的市场就是一个顺序博弈的例子。3435363738Strategic Behavior:Barriers of EntrynFour traditional barriers to entry(passive)nEconomies of scale,prod

24、uct differentiation,control over scare resources,and legal factors nMarket Entry Decision(Entry Game)(aggressive)nPresent vs.Future Profits:Entry-Limiting PricingnMain ideas:nMotivation:short-run Monopoly pricing practice earns“too much profits”,hence attract new entrants that will eat up the market

25、 share and drive down the prices in the long run nEntry-Limit Pricing:need to set a price below the short-run monopoly price(Fig 11-1,p.293)nFigure 11-2:profit streams 39Strategic Behavior:Barriers of EntrynStiglers Open Oligopoly ModelnObjective:maximize the present value of profitnIn some cases,th

26、is may be achieved by setting a price designed to deter entry nOptimal strategy depends on the discount rates used by the managers to determine the present value of profitnA ComparisonnEntry-Limiting Pricing:long-time horizon&a lower discount rate nOpen Oligopoly Model:short planning horizon&a bigge

27、r discount rate 40Strategic Behavior:Barriers of EntrynPrice Retaliation（价格报复）nIn contrast with Limit Pricing that keeps the price low over a long period of time,another strategic response to the threat of entry is to retaliate by reducing prices when entry actually does occur or it appears imminent

28、.nWhen the perceive danger has diminished,prices can be increased to whatever level management views as appropriate for market conditions.41Strategic Behavior:Barriers of EntrynEstablishing Commitment:Capacity Expansion（扩大生产能力）nA strategic response by established firms to prevent the new entrants fr

29、om occurring would be to invest in additional capacity.nOnce this investment has been made,it becomes a sunk cost and places existing firms in a position to expand their production as relatively low cost.The existence of excess capacity provides a strong signal that the established firms can(and pro

30、bably will)reduce prices as a strategic response to entry in their market.42Strategic Behavior:Barriers of EntrynPreemptive Action:Market Saturation(先发制人：使市场饱和)nOne entry-deterring strategy for the existing firm would be to disperse its production facilities.By the existing firm spreading its plants throughout the market area(the analysis of geographic saturation can also be applied to product characteristics)the opportunity for the new entrant to take advantage of high transportation costs is greatly reduced.nExample:Brand Proliferation in the Cereal Industry43