Contents Foreword xi Part I The basics 1 1 Existence vs. essence The opposition existence/essence 1.2 Essentialist and existentialist projects 1.3 and after Essentialism vs. Perfect vs. imperfect 2 Incompleteness 2.1 Technical statement 2.2 Hilbert in the face of incompleteness 2.3 Incompleteness is not a deficiency 2.4 Metaphorical readings 2. A More on the classification of predicates 2.B Formal arithmetic 2.C Techniques of incompleteness 2.D Incompleteness and truth 2.E Undecidability 34 36 38 3 Classical sequents: LK 3.1 Generalities 3.2 The classical calculus 3.3 The cut-free system 3.4 the Hauptsatz 3.A Around sequent calculus 3.B Semantic aspects 3.C Infinitary proof-theory 41 41 43 48 51 54 59 65 4 Intuitionistic logic: LJ, NJ The intuitionistic sequent calculus LJ 4.2 The Hauptsatz in LJ 4.3 The natural deduction NJ 4.4 The signature in natural deduction 70 70 73 75 Girard, Jean-Yves The blind spot cop. 2011 3 3 5 8 12 13 15 20 22 26 29 digitalisiert durch IDS Basel/Bern, im Auftrag der Schweizerischen Nationalbibliothek vi Contents 4.B 4.C 4.D Existence and disjunction in LJ Natural deduction vs. sequent calculus Around contraction Logic programming Kripke models Part II Around Curry-Howard 83 86 87 89 91 95 5 Functional interpretations 5.1 Proofs as functions 5.2 Pure 5.3 The Curry-Howard isomorphism Kreisel and functional interpretation 5.B Combinatory logic 5.C Other connectives 5.D type theory 6 System F 6.1 System F 6.2 The normalisation theorem Type theories 6.B Heyting's arithmetic 6.C T 6.D Expressive power Subtyping 6.F Essence, existence and typing 121 126 129 129 131 135 136 The category-theoretic interpretation 7.1 The three layers 7.2 Closed cartesian categories 7.3 Examples CCC 7.4 Logic CCC Classical logic 7.B Various interpretations 140 140 147 150 152 154 157 7 Part III 8 97 97 103 107 109 Linear logic Coherent spaces 8.1 Grandeur and misery of Scott domains 8.2 Coherent spaces 163 164 Contents 8.3 9 Interpretation of system F Asymmetric interpretations vii 171 175 Linear logic 9.1 Linearity in coherent spaces 9.2 Perfect linear connectives 9.3 Imperfect connectives 9.4 The logical system Monoidal categories 178 178 182 10 Perfection vs. imperfection 10.1 Phase semantics 10.2 A perfect world? 10.3 The world is imperfect 10.A Focalisation 197 197 202 208 210 11 Proof-nets 11.1 ILL Multiplicative nets 11.3 The correctness criterion More on multiplicatives 1 Syllogistic General nets 216 216 220 227 233 238 240 Part IV 12 13 Polarised interpretations 187 194 249 A hypothesis: polarisation 12.1 Faithfulness of coherent spaces A prototype 12.3 Objections to polarisation Logic and games 12.5 Proofs and tests 12.6 Hypersequentialised logic Classical polarity Intuitionistic logic 12.C Hypercoherences 251 254 256 257 260 262 267 269 270 Designs and behaviours 13.1 Designs-dessins 13.2 Designs-desseins 13.3 Partial designs 272 272 277 282 viii Contents 13.4 13.5 13.6 13.7 13.8 13.9 Nets and normalisation: dessins Nets and normalisation: desseins Analytical theorems Introspective vs. Behaviours An example: the shift 283 288 292 298 300 304 14 Ludics: the reconstruction 14.1 Additives 14.2 Multiplicatives 14.3 Quantifiers 14.A Faithfulness 14.B Bihaviours 14.C Parsimony 14.D (?) 306 306 316 320 324 326 328 329 15 Orthodox exponentials 15.1 The perennial perenniality 15.2 Exponential nets: normalisation 15.3 Categories and classical logic 15.4 The LC Exponentials and analytic functions Exponential ludics 15.C Polarised linear logic The 331 331 333 334 337 340 342 343 350 Part V Iconoclasm 355 16 Heterodox exponentials 16.1 The quarrel of images 16.2 Exponentials 16.3 Russell's antinomy 16.4 16.5 Expressive power 357 357 359 361 364 366 17 Quantum coherent spaces 17.1 Logic vs. quantum 17.2 Probabilistic coherent spaces 17.3 Quantum coherent spaces 17.4 Additives 17.5 Multiplicatives 369 369 373 375 380 387 Contents 18 ix 17.6 Discussion 17.A Initiation to 392 393 Nets and duality 18.1 Duality and correctness 18.2 The original criterion Trips and coherent spaces 18.B Non-commutative logic 403 403 406 409 410 Part VI Geometry of interaction 19 The feedback equation 19.1 Basic examples 19.2 Cut-systems 19.3 Solving the equation 19.4 The normal form 19.5 The first Complements on operators 417 417 419 421 425 432 439 20 Babel Tower vs. Great Wall 20.1 Idioms 20.2 The Babel Tower 20.3 20.A Von Neumann algebras 20.B Finite algebras 20.C Hyperfinite algebras 20.D The determinant 443 443 446 448 450 453 456 459 21 Finite 21.1 Projects 21.2 Conducts 21.3 The social life of conducts 21.4 Polarised conducts 21.5 Exponentials 21.6 Lateralised logic 21.7 The social life of behaviours Second-order quantification 21.B Truth Truth and intersubjectivity 462 462 469 473 475 477 480 482 485 488 491 x Contents Envoi. The phantom of transparency The transparent world Logics of transparency Semantics From semantics to the cognitive onion Negation 497 497 498 499 501 504 Bibliography 509 Index 517