平狄克微观经济学课件(英文)13.ppt

平狄克微观经济学课件(英文)13.ppt

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CHAPTER13OUTLINE,13.1GamingandStrategicDecisions13.2DominantStrategies13.3TheNashEquilibriumRevisited13.4RepeatedGames13.5SequentialGames13.6Threats,Commitments,andCredibility13.7EntryDeterrence13.8Auctions,GAMINGANDSTRATEGICDECISIONS,gameSituationinwhichplayers（participants）makestrategicdecisionsthattakeintoaccounteachothersactionsandresponses.,payoffValueassociatedwithapossibleoutcome.,strategyRuleorplanofactionforplayingagame.,optimalstrategyStrategythatmaximizesaplayersexpectedpayoff.,IfIbelievethatmycompetitorsarerationalandacttomaximizetheirownpayoffs,howshouldItaketheirbehaviorintoaccountwhenmakingmydecisions?

GAMINGANDSTRATEGICDECISIONS,cooperativegameGameinwhichparticipantscannegotiatebindingcontractsthatallowthemtoplanjointstrategies.,noncooperativegameGameinwhichnegotiationandenforcementofbindingcontractsarenotpossible.,NoncooperativeversusCooperativeGames,GAMINGANDSTRATEGICDECISIONS,NoncooperativeversusCooperativeGames,HowtoBuyaDollarBill,Adollarbillisauctioned,butinanunusualway.Thehighestbidderreceivesthedollarinreturnfortheamountbid.However,thesecond-highestbiddermustalsohandovertheamountthatheorshebidandgetnothinginreturn.Ifyouwereplayingthisgame,howmuchwouldyoubidforthedollarbill?

GAMINGANDSTRATEGICDECISIONS,YourepresentCompanyA,whichisconsideringacquiringCompanyT.YouplantooffercashforallofCompanyTsshares,butyouareunsurewhatpricetooffer.ThevalueofCompanyTdependsontheoutcomeofamajoroilexplorationproject.Iftheprojectsucceeds,CompanyTsvalueundercurrentmanagementcouldbeashighas$100/share.CompanyTwillbeworth50percentmoreunderthemanagementofCompanyA.Iftheprojectfails,CompanyTisworth$0/shareundereithermanagement.Thisoffermustbemadenowbeforetheoutcomeoftheexplorationprojectisknown.You（CompanyA）willnotknowtheresultsoftheexplorationprojectwhensubmittingyourpriceoffer,butCompanyTwillknowtheresultswhendecidingwhethertoacceptyouroffer.Also,CompanyTwillacceptanyofferbyCompanyAthatisgreaterthanthe（pershare）valueofthecompanyundercurrentmanagement.Youareconsideringpriceoffersintherange$0/share（i.e.,makingnoofferatall）to$150/share.WhatpricepershareshouldyouofferforCompanyTsstock?

Thetypicalresponsetoofferbetween$50and$75pershareiswrong.Thecorrectanswertothisproblemappearsattheendofthischapter.,DOMINANTSTRATEGIES,dominantstrategyStrategythatisoptimalnomatterwhatanopponentdoes.,SupposeFirmsAandBsellcompetingproductsandaredecidingwhethertoundertakeadvertisingcampaigns.Eachfirmwillbeaffectedbyitscompetitorsdecision.,DOMINANTSTRATEGIES,equilibriumindominantstrategiesOutcomeofagameinwhicheachfirmisdoingthebestitcanregardlessofwhatitscompetitorsaredoing.,Unfortunately,noteverygamehasadominantstrategyforeachplayer.Toseethis,letschangeouradvertisingexampleslightly.,THENASHEQUILIBRIUMREVISITED,TheProductChoiceProblem,Twobreakfastcerealcompaniesfaceamarketinwhichtwonewvariationsofcerealcanbesuccessfullyintroduced.,THENASHEQUILIBRIUMREVISITED,TheBeachLocationGame,You（Y）andacompetitor（C）plantosellsoftdrinksonabeach.Ifsunbathersarespreadevenlyacrossthebeachandwillwalktotheclosestvendor,thetwoofyouwilllocatenexttoeachotheratthecenterofthebeach.ThisistheonlyNashequilibrium.IfyourcompetitorlocatedatpointA,youwouldwanttomoveuntilyouwerejusttotheleft,whereyoucouldcapturethree-fourthsofallsales.Butyourcompetitorwouldthenwanttomovebacktothecenter,andyouwoulddothesame.,BeachLocationGame,Figure13.1,THENASHEQUILIBRIUMREVISITED,*MaximinStrategies,TheconceptofaNashequilibriumreliesheavilyonindividualrationality.Eachplayerschoiceofstrategydependsnotonlyonitsownrationality,butalsoontherationalityofitsopponent.Thiscanbealimitation.,maximinstrategyStrategythatmaximizestheminimumgainthatcanbeearned.,THENASHEQUILIBRIUMREVISITED,MaximinStrategies,IfFirm1isunsureaboutwhatFirm2willdobutcanassignprobabilitiestoeachfeasibleactionforFirm2,itcouldinsteaduseastrategythatmaximizesitsexpectedpayoff.,MaximizingtheExpectedPayoff,ThePrisonersDilemma,WhatistheNashequilibriumfortheprisonersdilemma?

THENASHEQUILIBRIUMREVISITED,*MixedStrategies,Inthisgame,eachplayerchoosesheadsortailsandthetwoplayersrevealtheircoinsatthesametime.Ifthecoinsmatch,PlayerAwinsandreceivesadollarfromPlayerB.Ifthecoinsdonotmatch,PlayerBwinsandreceivesadollarfromPlayerA.,purestrategyStrategyinwhichaplayermakesaspecificchoiceortakesaspecificaction.,MatchingPennies,mixedstrategyStrategyinwhichaplayermakesarandomchoiceamongtwoormorepossibleactions,basedonasetofchosenprobabilities.,THENASHEQUILIBRIUMREVISITED,*MixedStrategies,JimandJoanwouldliketospendSaturdaynighttogetherbuthavedifferenttastesinentertainment.Jimwouldliketogototheopera,butJoanprefersmudwrestling.,TheBattleoftheSexes,REPEATEDGAMES,Howdoesrepetitionchangethelikelyoutcomeofthegame?

repeatedgameGameinwhichactionsaretakenandpayoffsreceivedoverandoveragain.,REPEATEDGAMES,Supposethegameisinfinitelyrepeated.Inotherwords,mycompetitorandIrepeatedlysetpricesmonthaftermonth,forever.Withinfiniterepetitionofthegame,theexpectedgainsfromcooperationwilloutweighthosefromundercutting.,tit-for-tatstrategyRepeated-gamestrategyinwhichaplayerrespondsinkindtoanopponentspreviousplay,cooperatingwithcooperativeopponentsandretaliatingagainstuncooperativeones.,Tit-for-TatStrategy,InfinitelyRepeatedGame,REPEATEDGAMES,FiniteNumberofRepetitions,Nowsupposethegameisrepeatedafinitenumberoftimessay,Nmonths.Ifmycompetitor（Firm2）isrationalandbelievesthatIamrational,hewillreasonasfollows:

“BecauseFirm1isplayingtit-for-tat,I（Firm2）cannotundercutthatis,untilthelastmonth.IshouldundercutthelastmonthbecausethenIcanmakealargeprofitthatmonth,andafterwardthegameisover,soFirm1cannotretaliate.Therefore,Iwillchargeahighpriceuntilthelastmonth,andthenIwillchargealowprice.”However,sinceI（Firm1）havealsofiguredthisout,Ialsoplantochargealowpriceinthelastmonth.Firm2figuresthatitshouldundercutandchargealowpriceinthenext-to-lastmonth.Andbecausethesamereasoningappliestoeachprecedingmonth,thegameunravels:

Theonlyrationaloutcomeisforbothofustochargealowpriceeverymonth.,REPEATEDGAMES,Tit-for-TatinPractice,Sincemostofusdonotexpecttoliveforever,theunravelingargumentwouldseemtomakethetit-for-tatstrategyoflittlevalue,leavingusstuckintheprisonersdilemma.Inpractice,however,tit-for-tatcansometimesworkandcooperationcanprevail.Therearetwoprimaryreasons.Mostmanagersdontknowhowlongtheywillbecompetingwiththeirrivals,andthisalsoservestomakecooperativebehavioragoodstrategy.Mycompetitormighthavesomedoubtabouttheextentofmyrationality.Inarepeatedgame,theprisonersdilemmacanhaveacooperativeoutcome.,REPEATEDGAMES,AlmostallthewatermeterssoldintheUnitedStateshavebeenproducedbyfourAmericancompanies.RockwellInternationalhashadabouta35-percentshareofthemarket,andtheotherthreefirmshavetogetherhadabouta50-to55-percentshare.Mostbuyersofwatermetersaremunicipalwaterutilities,whoinstallthemetersinordertomeasurewaterconsumptionandbillconsumersaccordingly.Utilitiesareconcernedmainlythatthemetersbeaccurateandreliable.Priceisnotaprimaryissue,anddemandisveryinelastic.Becauseanynewentrantwillfinditdifficulttolurecustomersfromexistingfirms,thiscreatesabarriertoentry.Substantialeconomiesofscalecreateasecondbarriertoentry.Thefirmsthusfaceaprisonersdilemma.Cancooperationprevail?

Itcanandhasprevailed.Thereisrarelyanattempttoundercutprice,andeachfirmappearssatisfiedwithitsshareofthemarket.,REPEATEDGAMES,InMarch1983,AmericanAirlinesproposedthatallairlinesadoptauniformfareschedulebasedonmileage.Theratepermilewoulddependonthelengthofthetrip,withthelowestrateof15centspermilefortripsover2500milesandthehighestrate,53centspermile,fortripsunder250miles.WhydidAmericanproposethisplan,andwhatmadeitsoattractivetotheotherairlines?

Theaimwastoreducepricecompetitionandachieveacollusivepricingarrangement.Fixingpricesisillegal.Instead,thecompanieswouldimplicitlyfixpricesbyagreeingtousethesamefare-settingformula.Theplanfailed,avictimoftheprisonersdilemma.PanAm,whichwasdissatisfiedwithitssmallshareoftheU.S.market,droppeditsfares.American,United,andTWA,afraidoflosingtheirownsharesofthemarket,quicklydroppedtheirfarestomatchPanAm.Theprice-cuttingcontinued,andfortunatelyforconsumers,theplanwassoondead.,SEQUENTIALGAMES,Asasimpleexample,letsreturntotheproductchoiceproblem.Thistime,letschangethepayoffmatrixslightly.,sequentialgameGameinwhichplayersmoveinturn,respondingtoeachothersactionsandreactions.,SEQUENTIALGAMES,extensiveformofagameRepresentationofpossiblemovesinagameintheformofadecisiontree.,TheExtensiveFormofaGame,ProductChoiceGameinExtensiveForm,Figure13.2,SEQUENTIALGAMES,TheAdvantageofMovingFirst,THREATS,COMMITMENTS,ANDCREDIBILITY,SupposeFirm1producespersonalcomputersthatcanbeusedbothaswordprocessorsandtodoothertasks.Firm2producesonlydedicatedw