This page intentionally left blank CAMBRIDGE STUDIES IN ADVANCED MATHEMATICS 132 EditorialBoard B.BOLLOBÁS, W.FULTON, A.KATOK, F.KIRWAN, P.SARNAK, B.SIMON, B.TOTARO ModelsandGames Thisgentleintroductiontologicandmodeltheoryisbasedonasystematicuseofthree importantgamesinlogic:theSemanticGame,theEhrenfeucht–FraïsséGame,andthe ModelExistenceGame.Thethirdgamehasnotbeenisolatedintheliteraturebefore, butitunderliestheconceptsofBethtableauxandconsistencyproperties. JoukoVäänänenshowsthatthesegamesarecloselyrelatedand,inturn,governthe threeinterrelatedconceptsoflogic:truth,elementaryequivalence,andproof.Allthree methodsaredevelopednotonlyforfirst-orderlogic, butalsoforinfinitarylogicand generalizedquantifiers.Alongtheway,theauthoralsoprovescompletenesstheorems for many logics, including the cofinality quantifier logic of Shelah, a fully compact extensionoffirst-orderlogic. Withover500exercises,thisbookisidealforgraduatecourses,coveringthebasic materialaswellasmoreadvancedapplications. JoukoVäänänenisaProfessorofMathematicsattheUniversityofHelsinki, anda ProfessorofMathematicalLogicandFoundationsofMathematicsattheUniversityof Amsterdam. CAMBRIDGESTUDIESINADVANCEDMATHEMATICS EditorialBoard: B.Bollobás,W.Fulton,A.Katok,F.Kirwan,P.Sarnak,B.Simon,B.Totaro AllthetitleslistedbelowcanbeobtainedfromgoodbooksellersorfromCambridgeUniversityPress. Foracompleteserieslisting,visit:http://www.cambridge.org/series/sSeries.asp?code=CSAM Alreadypublished 84 R.A.BaileyAssociationschemes 85 J.Carlson,S.Müller-Stach&C.PetersPeriodmappingsandperioddomains 86 J.J.Duistermaat&J.A.C.KolkMultidimensionalrealanalysis,I 87 J.J.Duistermaat&J.A.C.KolkMultidimensionalrealanalysis,II 89 M.C.Golumbic&A.N.TrenkTolerancegraphs 90 L.H.HarperGlobalmethodsforcombinatorialisoperimetricproblems 91 I.Moerdijk&J.MrcˇunIntroductiontofoliationsandLiegroupoids 92 J.Kollár,K.E.Smith&A.CortiRationalandnearlyrationalvarieties 93 D.ApplebaumLévyprocessesandstochasticcalculus(1stEdition) 94 B.ConradModularformsandtheRamanujanconjecture 95 M.SchechterAnintroductiontononlinearanalysis 96 R.CarterLiealgebrasoffiniteandaffinetype 97 H.L.Montgomery&R.C.VaughanMultiplicativenumbertheory,I 98 I.ChavelRiemanniangeometry(2ndEdition) 99 D.GoldfeldAutomorphicformsandL-functionsforthegroupGL(n,R) 100 M.B.Marcus&J.RosenMarkovprocesses,Gaussianprocesses,andlocaltimes 101 P.Gille&T.SzamuelyCentralsimplealgebrasandGaloiscohomology 102 J.BertoinRandomfragmentationandcoagulationprocesses 103 E.FrenkelLanglandscorrespondenceforloopgroups 104 A.Ambrosetti&A.MalchiodiNonlinearanalysisandsemilinearellipticproblems 105 T.Tao&V.H.VuAdditivecombinatorics 106 E.B.DaviesLinearoperatorsandtheirspectra 107 K.KodairaComplexanalysis 108 T.Ceccherini-Silberstein,F.Scarabotti&F.TolliHarmonicanalysisonfinitegroups 109 H.GeigesAnintroductiontocontacttopology 110 J.FarautAnalysisonLiegroups:AnIntroduction 111 E.ParkComplextopologicalK-theory 112 D.W.StroockPartialdifferentialequationsforprobabilists 113 A.Kirillov,JrAnintroductiontoLiegroupsandLiealgebras 114 F.Gesztesyetal.Solitonequationsandtheiralgebro-geometricsolutions,II 115 E.deFaria&W.deMeloMathematicaltoolsforone-dimensionaldynamics 116 D.ApplebaumLévyprocessesandstochasticcalculus(2ndEdition) 117 T.SzamuelyGaloisgroupsandfundamentalgroups 118 G.W.Anderson,A.Guionnet&O.ZeitouniAnintroductiontorandommatrices 119 C.Perez-Garcia&W.H.SchikhofLocallyconvexspacesovernon-Archimedeanvaluedfields 120 P.K.Friz&N.B.VictoirMultidimensionalstochasticprocessesasroughpaths 121 T.Ceccherini-Silberstein,F.Scarabotti&F.TolliRepresentationtheoryofthesymmetricgroups 122 S.Kalikow&R.McCutcheonAnoutlineofergodictheory 123 G.F.Lawler&V.LimicRandomwalk:Amodernintroduction 124 K.Lux&H.PahlingsRepresentationsofgroups 125 K.S.Kedlayap-adicdifferentialequations 126 R.Beals&R.WongSpecialfunctions 127 E.deFaria&W.deMeloMathematicalaspectsofquantumfieldtheory 128 A.TerrasZetafunctionsofgraphs 129 D.Goldfeld&J.HundleyAutomorphicrepresentationsandL-functionsforthegenerallinear group,I 130 D.Goldfeld&J.HundleyAutomorphicrepresentationsandL-functionsforthegenerallinear group,II 131 DavidA.CravenThetheoryoffusionsystems Models and Games JOUKO VÄÄNÄNEN UniversityofHelsinki UniversityofAmsterdam cambridge university press Cambridge,NewYork,Melbourne,Madrid,CapeTown, Singapore,SãoPaulo,Delhi,Tokyo,MexicoCity CambridgeUniversityPress TheEdinburghBuilding,CambridgeCB28RU,UK PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork www.cambridge.org Informationonthistitle:www.cambridge.org/9780521518123 ©J.Väänänen2011 Thispublicationisincopyright.Subjecttostatutoryexception andtotheprovisionsofrelevantcollectivelicensingagreements, noreproductionofanypartmaytakeplacewithoutthewritten permissionofCambridgeUniversityPress. Firstpublished2011 PrintedintheUnitedKingdomattheUniversityPress,Cambridge AcatalogrecordforthispublicationisavailablefromtheBritishLibrary ISBN978-0-521-51812-3Hardback CambridgeUniversityPresshasnoresponsibilityforthepersistenceor accuracyofURLsforexternalorthird-partyinternetwebsitesreferredto inthispublication,anddoesnotguaranteethatanycontentonsuch websitesis,orwillremain,accurateorappropriate. ToJuliette Contents Preface pagexi 1 Introduction 1 2 PreliminariesandNotation 3 2.1 FiniteSequences 3 2.2 Equipollence 5 2.3 Countablesets 6 2.4 Ordinals 7 2.5 Cardinals 9 2.6 AxiomofChoice 10 2.7 HistoricalRemarksandReferences 11 Exercises 11 3 Games 14 3.1 Introduction 14 3.2 Two-PersonGamesofPerfectInformation 14 3.3 TheMathematicalConceptofGame 20 3.4 GamePositions 21 3.5 InfiniteGames 24 3.6 HistoricalRemarksandReferences 28 Exercises 28 4 Graphs 35 4.1 Introduction 35 4.2 First-OrderLanguageofGraphs 35 4.3 TheEhrenfeucht–Fra¨ısse´ GameonGraphs 38 4.4 Ehrenfeucht–Fra¨ısse´ GamesandElementaryEquivalence 43 4.5 HistoricalRemarksandReferences 48 Exercises 49 viii Contents 5 Models 53 5.1 Introduction 53 5.2 BasicConcepts 54 5.3 Substructures 62 5.4 Back-and-ForthSets 63 5.5 TheEhrenfeucht–Fra¨ısse´ Game 65 5.6 Back-and-ForthSequences 69 5.7 HistoricalRemarksandReferences 71 Exercises 71 6 First-OrderLogic 79 6.1 Introduction 79 6.2 BasicConcepts 79 6.3 CharacterizingElementaryEquivalence 81 6.4 TheLo¨wenheim–SkolemTheorem 85 6.5 TheSemanticGame 93 6.6 TheModelExistenceGame 98 6.7 Applications 102 6.8 Interpolation 107 6.9 UncountableVocabularies 113 6.10 Ultraproducts 119 6.11 HistoricalRemarksandReferences 125 Exercises 126 7 InfinitaryLogic 139 7.1 Introduction 139 7.2 PreliminaryExamples 139 7.3 TheDynamicEhrenfeucht–Fra¨ısse´ Game 144 7.4 SyntaxandSemanticsofInfinitaryLogic 157 7.5 HistoricalRemarksandReferences 170 Exercises 171 8 ModelTheoryofInfinitaryLogic 176 8.1 Introduction 176 8.2 Lo¨wenheim–SkolemTheoremforL 176 ∞ω 8.3 ModelTheoryofL 179 ω1ω 8.4 LargeModels 184 8.5 ModelTheoryofL 191 κ+ω 8.6 GameLogic 201 8.7 HistoricalRemarksandReferences 222 Exercises 223