微觀經(jīng)濟學之博弈論與競爭策略

Chapter13博弈論與競爭策略Chapter13Slide2本章討論的主題博弈和策略性決策占優(yōu)策略納什均衡回顧重復(fù)博弈序貫博弈威脅、承諾和可信性對進入的阻止拍賣Chapter13Slide313.1博弈和策略性決策“如果我相信我的競爭者是理性的且追求最大化利潤，那么在做我自己利潤最大化的決策時，我應(yīng)該如何將其行為考慮在內(nèi)呢？”博弈就是研究各參與者行為發(fā)生直接的相互作用時，博弈參與者將每個其他參與者的行動和反應(yīng)考慮在內(nèi)進行的決策及其均衡的理論和方法。博弈的結(jié)果：博弈均衡。所謂博弈均衡指博弈中的參與者都不想改變自己的策略的這樣一種狀態(tài)。Chapter13Slide4博弈的基本要素參與人/局中人player：博弈中的決策主體；策略strategy：參與人在博弈中遵循的行動規(guī)制或計劃；參與者最有策略是能夠最大化其期望支付的策略；支付/報酬payoff:參與人在某個特定策略組合下獲得的回報。Chapter13Slide5博弈的分類:非合作博弈和合作博弈合作博弈：各參與者能談定能使它們設(shè)計的聯(lián)合策略的有約束力的合同的博弈。如兩個廠商談判開發(fā)一種新技術(shù)的聯(lián)合投資(其中任何一個廠商都沒有能獨自成功的足夠知識)，如果兩個廠商能夠簽訂一份分配聯(lián)合投資利潤的有約束力的合同,則使雙研究決策主體的行為發(fā)生直接的相互作用時方都獲益的合作結(jié)果就是可能的.非合作博弈：參與方步可能談判并執(zhí)行有約束力的合同的談判。如兩個競爭廠商相互考慮到對方可能采取的行動，并獨立確定價格。Chapter13Slide6策略性決策制定的關(guān)鍵：策略性決策制定的關(guān)鍵：理解你的對手的觀點，并推斷他（她）對你的行動的大概會如何反應(yīng)。Chapter13Slide7GamingandStrategicDecisionsAnExample:Howtobuyadollarbill 1) Auctionadollarbill 2) Highestbidderreceivesthedollarin returnfortheamountbidChapter13Slide8GamingandStrategicDecisionsAnExample 3) Secondhighestbiddermustpaythe amountheorshebid 4) Howmuchwouldyoubidfora dollar?Chapter13Slide9AcquiringaCompanyScenarioCompanyA:TheAcquirerCompanyT:TheTargetAwilloffercashforallofT’ssharesWhatpricetooffer?Chapter13Slide10AcquiringaCompanyScenarioThevalueofTdependsontheoutcomeofacurrentoilexplorationproject.Failure:T’svalue=$0Success:T’svalue=$100/shareAlloutcomesareequallylikelyChapter13Slide11AcquiringaCompanyScenarioT’svaluewillbe50%greaterwithA’smanagement.A,mustsubmittheproposalbeforetheexplorationoutcomeisknown.TwillnotchoosetoacceptorrejectuntilaftertheoutcomeisknownonlytoT.HowmuchshouldAoffer?Chapter13Slide1213.2占優(yōu)策略含義：無論對手選擇什么策略，我選擇的策略都是我所能選擇的最優(yōu)策略，稱為占優(yōu)策略。占優(yōu)策略均衡，即博弈中所有的參與者都采取自己的占優(yōu)策略構(gòu)成的均衡。一個例子：廠商A和

廠商B銷售相互競爭產(chǎn)品，并正在決定是否采取廣告計劃。Chapter13Slide13廣告博弈的支付矩陣FirmA做廣告不做廣告做廣告不做廣告廠商B10,515,010,26,8觀察：廠商A：不管廠商B如何決策，廠商A做廣告是其最優(yōu)策略；廠商B：不管廠商B如何決策，廠商A做廣告是其最優(yōu)策略；Chapter13Slide14廣告的支付矩陣廠商A做廣告不做廣告做廣告不做廣告廠商B10,515,010,26,8觀察廠商A和廠商B的占優(yōu)策略是做廣告；博弈的結(jié)果:占優(yōu)策略均衡，即博弈中所有的參與者都采取自己的占優(yōu)策略構(gòu)成的均衡。Chapter13Slide15沒有占優(yōu)策略的博弈不是每個博弈的各個參與者都有一個占優(yōu)策略。沒有占優(yōu)策略的參與者的最優(yōu)決策取決于其他參與者采取了什么行動。Chapter13Slide1610,515,020,26,8廠商A做廣告不做廣告做廣告不做廣告廠商B修正后的廣告博弈觀察廠商A:沒有占優(yōu)策略；取決于B的行動；廠商B:做廣告；

問題：廠商A將如何行動?(提示:考慮B的決策)Chapter13Slide1713.3納什均衡回顧在許多博弈中，一個或多個參與者沒有占優(yōu)策略，我們需要尋找一種更一般的均衡概念。納什均衡：一組滿足給定對手的行動時各參與者所做的是它所能做的最好的策略（或行動）。在一個納什均衡里，如果其他參與者不改變策略，任何一個參與者都不會改變自己的策略，因此這種策略是穩(wěn)定的。Chapter13Slide18納什均衡與占優(yōu)策略均衡占優(yōu)策略均衡不管你做什么，我所做的都是我能做的最好的；不管我做什么，你所做的都是你能做的最好的。納什均衡給定你所做的，我所做的是我所能做的最好的；給定我所做的，你所做的是你所能做的最好的；占優(yōu)策略均衡與納什均衡的關(guān)系：占優(yōu)策略均衡一定是納什均衡，納什均衡不一定是占優(yōu)策略均衡。Chapter13Slide19兩個早餐麥片公司每家公司都有兩個策略：針對新型“脆”麥片市場；針對新型“甜”麥片市場；每一家廠商只有推出一種新產(chǎn)品的資源；兩家公司進行非合作博弈；納什均衡例1：產(chǎn)品選擇問題Chapter13Slide20產(chǎn)品選型問題廠商1脆甜脆甜廠商2-5,-510,10-5,-510,10Chapter13Slide21產(chǎn)品選型問題廠商1脆甜脆甜廠商2-5,-510,10-5,-510,10問題存在納什均衡嗎？如果不存在，為什么?如果存在，如何達到？Chapter13Slide22納什均衡例2：海灘選擇博弈兩個競爭者：你(Y)和競爭者(C),計劃在沙灘上出售軟飲料；沙灘長200碼；陽光浴者均勻分布在海灘上；你的定價=你的競爭者定價顧客將選擇距離最近的銷售點購買。Chapter13Slide23海灘選擇博弈你將選擇在海灘的什么地點銷售？你認為你的競爭對手會如何選擇(即納什均衡的選址在何處)?此類決策問題還包括：加油站選址、總統(tǒng)選舉。Ocean0BBeachA200yardsC&YChapter13Slide24納什均衡求解：例1

7103568

89LRUD甲乙Chapter13Slide25納什均衡求解:例20，44，05，34，00，45，33，55，36，6LMRUMD參與人B

參與人AChapter13Slide26極大化極小策略含義：指博弈方在所能選擇的各種最小得益中求取得益的“最大化”。Chapter13Slide27競爭銷售文檔加密軟件博弈情景描述兩個廠商競爭銷售文檔加密軟件他們都使用相同的加密標準(某廠商軟件加密過的文件能夠被另一廠商的軟件閱讀——對消費者有好處)；廠商1有更大的市場份額；雙方都在考慮是否投資引入新的加密標準Chapter13Slide28競爭銷售文檔加密軟件博弈廠商1不投資投資廠商20,0-10,1020,10-100,0不投資投資Chapter13Slide29競爭銷售文檔加密軟件博弈觀察：廠商2有一個占優(yōu)策略：投資；因此廠商1預(yù)期廠商2會采取“投資”的策略，在這種情況下，他將采取“投資”的策略，顯然(投資,投資)是該博弈的納什均衡。但廠商2必須確信廠商1是理性的。如果廠商1無法確信廠商2是理性或信息不完全，出現(xiàn)了一點偏差，采取“不投資”的策略，則廠商1承受巨大的損失(-100),廠商1可能會選擇“不投資”，廠商1最壞的情形是損失10，而不是100。Chapter13Slide30注意：納什均衡極端依附個人理性，各博弈方的策略選擇不只取決于他本人的理性，而且也與決于它的對手的理性。最大化可能得到的最小好處即為極大化極小策略，這種一種風險最小策略，是保守的、而不是利潤最大化的策略。有時候納什均衡也是一個極大化極小策略均衡。Chapter13Slide31極大化極小策略廠商1不投資投資廠商20,0-10,1020,10-100,0不投資投資觀察廠商2的占優(yōu)策略:投資納什均衡廠商1:投資廠商2:投資Chapter13Slide32極大化極小策略觀察如果廠商2不投資(廠商2的決策出現(xiàn)偏差),廠商

1將發(fā)生高昂的損失廠商1

可能會選擇不投資,廠商1最壞的情形是損失10，而不是100——極大化極小策略極大化極小策略不是利潤最大化的，而是一種風險最小策略，保守策略。廠商1不投資投資廠商20,0-10,1020,10-100,0不投資投資Chapter13Slide33囚徒困境張三和李四兩廝偷車時被捕，警察懷疑他倆是本市一系列偷車案的慣犯，但沒有充分證據(jù)，為防止兩人串供，關(guān)在兩間牢房分別審問：如某人坦白，供出另一人，并把主要罪名推給對方，輕判年，對方判10年如兩人均坦白，各判5年如兩人拒不坦白，證據(jù)不足，罪名較輕，各判2年Chapter13Slide34囚徒困境PrisonerAConfessDon’tConfessConfessDon’tConfessPrisonerB-5,-5-1,-10-2,-2-10,-1Chapter13Slide35囚徒困境囚犯A坦白不坦白坦白不坦白囚犯B-5,-5-1,-10-2,-2-10,-1什么是:占優(yōu)策略納什均衡極大化極小策略Chapter13Slide36PureStrategyPlayermakesaspecificchoiceMixedStrategyPlayermakesarandomchoiceamongtwoormorepossibleactionsbasedonasetofchosenprobabilitiesTheNashEquilibriumRevisitedMixedStrategyChapter13Slide37MatchingPenniesPlayerAHeadsTailsHeadsTailsPlayerB1,-1-1,11,-1-1,1Chapter13Slide38MatchingPenniesPlayerAHeadsTailsHeadsTailsPlayerB1,-1-1,11,-1-1,1ObservationsPurestrategy:NoNashequilibriumMixedstrategy:RandomchoiceisaNashequilibriumWouldafirmsetpricebasedonrandomchoiceassumption?Chapter13Slide39TheBattleoftheSexesJimWrestlingOperaWrestlingOperaJoan2,10,01,20,0Chapter13Slide40TheBattleoftheSexesJimWrestlingOperaWrestlingOperaJoan2,10,01,20,0PureStrategyBothwatchwrestlingBothwatchoperaMixedStrategyJimchooseswrestlingJoanchooseswrestlingChapter13Slide4113.4重復(fù)博弈——破解囚徒困境重復(fù)博弈：即一個簡單的靜態(tài)博弈進行有限多期（有限次重復(fù)博弈），甚至無窮期（無限次重復(fù)博弈，也稱超級博弈）。在“囚徒困境”中博弈只進行一次，使博弈各方之間無法對背叛者進行處罰，若同樣的博弈進行無限次，各方可采取“以以牙還牙”的策略（即你這次違約，我下次違約，你這次守約，我下次守約）進行報復(fù)，最終大家合作。Chapter13Slide42PricingProblemFirm1LowPriceHighPriceLowPriceHighPriceFirm210,10100,-5050,50-50,100Chapter13Slide43PricingProblemFirm1LowPriceHighPriceLowPriceHighPriceFirm210,10100,-5050,50-50,100Non-repeatedgameStrategyisLow1,Low2RepeatedgameTit-for-tatstrategyisthemostprofitableChapter13Slide4413.4重復(fù)博弈Conclusion:WithrepeatedgameThePrisoners’Dilemmacanhaveacooperativeoutcomewithtit-for-tatstrategyChapter13Slide45RepeatedGamesConclusion:Thisismostlikelytooccurinamarketwith:FewfirmsStabledemandStablecostChapter13Slide46RepeatedGamesConclusionCooperationisdifficultatbestsincethesefactorsmaychangeinthelong-run.Chapter13Slide47OligopolisticCooperation

intheWaterMeterIndustryCharacteristicsoftheMarketFourProducersRockwellInternational(35%),BadgerMeter,NeptuneWaterMeterCompany,andHerseyProducts(Badger,Neptune,andHerseycombinedhaveabouta50to55%share)Chapter13Slide48OligopolisticCooperation

intheWaterMeterIndustryCharacteristicsoftheMarketVeryinelasticdemandNotasignificantpartofthebudgetChapter13Slide49CharacteristicsoftheMarketStabledemandLongstandingrelationshipbetweenconsumerandproducerBarrierEconomiesofscaleBarrierOligopolisticCooperation

intheWaterMeterIndustryChapter13Slide50CharacteristicsoftheMarketThisisaPrisoners’DilemmaLowerpricetoacompetitivelevelCooperateRepeatedGameQuestionWhyhascooperationprevailed?OligopolisticCooperation

intheWaterMeterIndustryChapter13Slide51WhatDoYouThink?Istherecooperation&collusionintheairlineindustry?CompetitionandCollusion

intheAirlineIndustryChapter13Slide52SequentialGamesPlayersmoveinturnPlayersmustthinkthroughthepossibleactionsandrationalreactionsofeachplayerChapter13Slide53SequentialGamesExamplesRespondingtoacompetitor’sadcampaignEntrydecisionsRespondingtoregulatorypolicyChapter13Slide54ScenarioTwonew(sweet,crispy)cerealsSuccessfulonlyifeachfirmproducesonecerealSweetwillsellbetterBothstillprofitablewithonlyoneproducerSequentialGamesTheExtensiveFormofaGameChapter13Slide55ModifiedProductChoiceProblemFirm1CrispySweetCrispySweetFirm2-5,-510,20-5,-520,10Chapter13Slide56ModifiedProductChoiceProblemFirm1CrispySweetCrispySweetFirm2-5,-510,20-5,-520,10QuestionWhatisthelikelyoutcomeifbothmaketheirdecisionsindependently,simultaneously,andwithoutknowledgeoftheother’sintentions?Chapter13Slide57AssumethatFirm1willintroduceitsnewcerealfirst(asequentialgame).QuestionWhatwillbetheoutcomeofthisgame?ModifiedProductChoiceProblemTheExtensiveFormofaGameChapter13Slide58SequentialGamesTheExtensiveFormofaGameUsingadecisiontreeWorkbackwardfromthebestoutcomeforFirm1TheExtensiveFormofaGameChapter13Slide59ProductChoiceGameinExtensiveFormCrispySweetCrispySweet-5,-510,2020,10-5,-5Firm1CrispySweetFirm2Firm2Chapter13Slide60SequentialGamesTheAdvantageofMovingFirstInthisproduct-choicegame,thereisaclearadvantagetomovingfirst.Chapter13Slide61SequentialGamesAssume:DuopolyTheAdvantageofMovingFirstChapter13Slide62SequentialGamesDuopolyTheAdvantageofMovingFirstChapter13Slide63ChoosingOutputFirm17.5Firm2112.50,112.5056.25,112.500,0112.50,56.25125,93.7550,7593.75,12575,50100,10010157.51015Chapter13Slide64ChoosingOutputFirm17.5Firm2112.50,112.5056.25,112.500,0112.50,56.25125,93.7550,7593.75,12575,50100,10010157.51015ThispayoffmatrixillustratesvariousoutcomesMovetogether,bothproduce10QuestionWhatifFirm1movesfirst?Chapter13Slide65Threats,Commitments,andCredibilityStrategicMovesWhatactionscanafirmtaketogainadvantageinthemarketplace?DeterentryInducecompetitorstoreduceoutput,leave,raisepriceImplicitagreementsthatbenefitonefirmChapter13Slide66HowToMaketheFirstMoveDemonstrateCommitmentFirm1mustconstrainhisbehaviortotheextentFirm

2isconvincedthatheiscommittedThreats,Commitments,andCredibilityChapter13Slide67EmptyThreatsIfafirmwillbeworseoffifitchargesalowprice,thethreatofalowpriceisnotcredibleintheeyesofthecompetitors.Threats,Commitments,andCredibilityChapter13Slide68PricingofComputers

andWordProcessorsFirm1HighPriceLowPriceHighPriceLowPriceFirm2100,8080,10010,2020,0Chapter13Slide69PricingofComputers

andWordProcessorsFirm1HighPriceLowPriceHighPriceLowPriceFirm2100,8080,10010,2020,0QuestionCanFirm1forceFirm

2tochargeahighpricebythreateningtoloweritsprice?Chapter13Slide70ScenarioRaceCarMotors,Inc.(RCM)producescarsFarOutEngines(FOE)producesspecialtycarenginesandsellsmostofthemtoRCMSequentialgamewithRCMastheleaderFOEhasnopowertothreatentobuildbigsinceRCMcontrolsoutput.Threats,Commitments,andCredibilityChapter13Slide71ProductionChoiceProblemFarOutEnginesSmallcarsBigcarsSmallenginesBigenginesRaceCarMotors3,63,08,31,1Chapter13Slide72QuestionHowcouldFOEforceRCMtoshifttobigcars?Threats,Commitments,andCredibilityChapter13Slide73ModifiedProductionChoiceProblem0,60,08,31,1FarOutEnginesSmallcarsBigcarsSmallenginesBigenginesRaceCarMotorsChapter13Slide74Questions 1) Whatistheriskofthisstrategy? 2) Howcouldirrationalbehaviorgive FOEsomepowertocontroloutput?ModifiedProductionChoiceProblemChapter13Slide75Wal-MartStores’

PreemptiveInvestmentStrategyQuestionHowdidWal-MartbecomethelargestretailerintheU.S.whenmanyestablishedretailchainswereclosingtheirdoors?HintHowdidWal-Martgainmonopolypower?PreemptivegamewithNashequilibriumChapter13Slide76TheDiscountStorePreemptionGameWal-MartEnterDon’tenterEnterDon’tenterCompanyX-10,-1020,00,00,20Chapter13Slide77TheDiscountStorePreemptionGameWal-MartEnterDon’tenterEnterDon’tenterCompanyX-10,-1020,00,00,20TwoNashequilibriumLowleftUpperrightMustbepreemptivetowinChapter13Slide78EntryDeterrenceTodeterentry,theincumbentfirmmustconvinceanypotentialcompetitorthatentrywillbeunprofitable.Chapter13Slide79EntryPossibilitiesIncumbentEnterStayoutHighprice(accommodation)LowPrice(warfare)PotentialEntrant100,20200,0130,070,-10Chapter13Slide80EntryDeterrenceScenarioIncumbentmonopolist(I)andprospectiveentrant(X)Xsinglecost=$80milliontobuildplantChapter13Slide81EntryDeterrenceScenarioIfXdoesnotenterImakesaprofitof$200million.IfXentersandchargesahighpriceIearnsaprofitof$100millionandXearns$20million.IfXentersandchargesalowpriceIearnsaprofitof$70millionandXearns$-10million.Chapter13Slide82EntryDeterrenceQuestionHowcouldIkeepXout? Isthethreatcredible?Chapter13Slide83EntryDeterrenceHowcouldIkeepXout? 1) Makeaninvestmentbeforeentry (irrevocablecommitment) 2) IrrationalbehaviorChapter13Slide84EntryDeterrenceIncumbentEnterStayoutHighprice(accommodation)LowPrice(warfare)PotentialEntrant50,20150,0130,070,-10After$50millionEarlyInvestmentChapter13Slide85EntryDeterrenceIncumbentEnterStayoutHighprice(accommodation)LowPrice(warfare)PotentialEntrant50,20150,0130,070,-10After$50millionEarlyInvestmentWarfarelikelyXwillstayoutChapter13Slide86Airbusvs.BoeingWithoutAirbusbeingsubsidized,thepayoffmatrixforthetwofirmswoulddiffersignificantlyfromoneshowingsubsidization.EntryDeterrenceChapter13Slide87DevelopmentofaNewAircraftBoeingProduceDon’tproduceAirbus-10,-10100,00,00,120ProduceDon’tproduceChapter13Slide88DevelopmentofaNewAircraftBoeingProduceDon’tproduceAirbus-10,-10100,00,00,120ProduceDon’tproduceBoeingwillproduceAirbuswillnotproduceChapter13Slide89DevelopmentofaAircraft

AfterEuropeanSubsidyBoeingProduceDon’tproduceAirbus-10,10100,00,00,120ProduceDon’tproduceChapter13Slide90BoeingProduceDon’tproduceAirbus-10,10100,00,00,120ProduceDon’tproduceAirbuswillproduceBoeingwillnotproduceDevelopmentofaAircraft

AfterEuropeanSubsidyChapter13Slide91DiaperWarsEventhoughthereareonlytwomajorfirms,competitionisintense.Thecompetitionoccursmostlyintheformofcost-reducing

innovation.Chapter13Slide92CompetingThroughR&DP&GR&DNoR&DR&DNoR&DKimberly-Clark40,2080,-2060,40-20,60Chapter13Slide93CompetingThroughR&DP&GR&DNoR&DR&DNoR&DKimberly-Clark40,2080,-2060,40-20,60BothspendonR&DQuestionWhynotcooperateChapter13Slide94BargainingStrategyAlternativeoutcomesarepossibleiffirmsorindividualscanmakepromisesthatcanbeenforced.Chapter13Slide95BargainingStrategyConsider:Twofirmsintroducingoneoftwocomplementarygoods.Chapter13Slide96BargainingStrategyFirm1ProduceAProduceBProduceAProduceBFirm240,550,505,4560,40Chapter13Slide97BargainingStrategyFirm1ProduceAProduceBProduceAProduceBFirm240,550,505,4560,40Withcollusion:ProduceA1B2Withoutcollusion:ProduceA1B2NashequilibriumChapter13Slide98BargainingStrategySupposeEachfirmisalsobargainingonthedecisiontojoininaresearchconsortiumwithathirdfirm.Chapter13Slide99BargainingStrategyFirm1WorkaloneEnterconsortiumWorkaloneEnterconsortiumFirm210,1010,2040,4020,10Chapter13Slide100BargainingStrategyFirm1WorkaloneEnterconsortiumWorkaloneEnterconsortiumFirm210,1010,2040,4020,10DominantstrategyBothenterChapter13Slide101BargainingStrategyLinkingtheBargainProblemFirm1announcesitwilljointheconsortiumonlyifFirm2agreestoproduceAandFirm1willproduceB.Firm1’sprofitincreasesfrom50to60Chapter13Slide102BargainingStrategyStrengtheningBargainingPowerCredibilityReducingflexibilityChapter13Slide103AuctionsAuctionFormatsTraditionalEnglish(oral)DutchauctionSealed-bidFirstpriceSecondpriceChapter13Slide104AuctionsHowtochooseanauctionformatPrivate-valueauction:biddersuncertainabouttheotherbiddersreservationpriceCommon-valueauction:biddersuncertainwhatthevalueisValuationandInformationChapter13Slide105AuctionsSecond-pricesealedauction:bidyourreservationpriceEnglishauction:BidinsmallincrementsuntilyoureachyourreservationpricePrivateValueAuctionChapter13Slide106AuctionsThewinningbidsinbothauctionsisthereservationpriceof