65 Graduate Texts in Mathematics Editorial Board S. Axler K.A.Ribet Graduate Texts in Mathematics 1 TAKEUTI/ZARING.Introduction to 34 SPITZER.Principles ofRandom Walk. Axiomatic Set Theory.2nd ed. 2nd ed. 2 OXTOBY.Measure and Category.2nd ed. 35 ALEXANDER/WERMER.Several Complex 3 SCHAEFER.Topological Vector Spaces. Variables and Banach Algebras.3rd ed. 2nd ed. 36 KELLEY/NAMIOKAet al.Linear 4 HILTON/STAMMBACH.A Course in Topological Spaces. Homological Algebra.2nd ed. 37 MONK.Mathematical Logic. 5 MACLANE.Categories for the Working 38 GRAUERT/FRITZSCHE.Several Complex Mathematician.2nd ed. Variables. 6 HUGHES/PIPER.Projective Planes. 39 ARVESON.An Invitation to C*-Algebras. 7 J.-P.SERRE.A Course in Arithmetic. 40 KEMENY/SNELL/KNAPP.Denumerable 8 TAKEUTI/ZARING.Axiomatic Set Theory. Markov Chains.2nd ed. 9 HUMPHREYS.Introduction to Lie 41 APOSTOL.Modular Functions and Algebras and Representation Theory. Dirichlet Series in Number Theory. 10 COHEN.A Course in Simple Homotopy 2nd ed. Theory. 42 J.-P.SERRE.Linear Representations of 11 CONWAY.Functions ofOne Complex Finite Groups. Variable I.2nd ed. 43 GILLMAN/JERISON.Rings of 12 BEALS.Advanced Mathematical Analysis. Continuous Functions. 13 ANDERSON/FULLER.Rings and 44 KENDIG.Elementary Algebraic Categories ofModules.2nd ed. Geometry. 14 GOLUBITSKY/GUILLEMIN.Stable 45 LOÈVE.Probability Theory I.4th ed. Mappings and Their Singularities. 46 LOÈVE.Probability Theory II.4th ed. 15 BERBERIAN.Lectures in Functional 47 MOISE.Geometric Topology in Analysis and Operator Theory. Dimensions 2 and 3. 16 WINTER.The Structure ofFields. 48 SACHS/WU.General Relativity for 17 ROSENBLATT.Random Processes.2nd ed. Mathematicians. 18 HALMOS.Measure Theory. 49 GRUENBERG/WEIR.Linear Geometry. 19 HALMOS.A Hilbert Space Problem 2nd ed. Book.2nd ed. 50 EDWARDS.Fermat's Last Theorem. 20 HUSEMOLLER.Fibre Bundles.3rd ed. 51 KLINGENBERG.A Course in Differential 21 HUMPHREYS.Linear Algebraic Groups. Geometry. 22 BARNES/MACK.An Algebraic 52 HARTSHORNE.Algebraic Geometry. Introduction to Mathematical Logic. 53 MANIN.A Course in Mathematical Logic. 23 GREUB.Linear Algebra.4th ed. 54 GRAVER/WATKINS.Combinatorics with 24 HOLMES.Geometric Functional Emphasis on the Theory ofGraphs. Analysis and Its Applications. 55 BROWN/PEARCY.Introduction to 25 HEWITT/STROMBERG.Real and Abstract Operator Theory I:Elements of Analysis. Functional Analysis. 26 MANES.Algebraic Theories. 56 MASSEY.Algebraic Topology:An 27 KELLEY.General Topology. Introduction. 28 ZARISKI/SAMUEL.Commutative 57 CROWELL/FOX.Introduction to Knot Algebra.Vol.I. Theory. 29 ZARISKI/SAMUEL.Commutative 58 KOBLITZ.p-adic Numbers,p-adic Algebra.Vol.II. Analysis,and Zeta-Functions.2nd ed. 30 JACOBSON.Lectures in Abstract Algebra 59 LANG.Cyclotomic Fields. I.Basic Concepts. 60 ARNOLD.Mathematical Methods in 31 JACOBSON.Lectures in Abstract Algebra Classical Mechanics.2nd ed. II.Linear Algebra. 61 WHITEHEAD.Elements ofHomotopy 32 JACOBSON.Lectures in Abstract Algebra Theory. III.Theory ofFields and Galois 62 KARGAPOLOV/MERIZJAKOV. Theory. Fundamentals ofthe Theory ofGroups. 33 HIRSCH.Differential Topology. 63 BOLLOBAS.Graph Theory. (continued after the subject index) Raymond O. Wells, Jr. Differential Analysis on Complex Manifolds Third Edition New Appendix By Oscar Garcia-Prada RaymondO. Wells, Jr. Jacobs University Bremen Campus Ring 1 28759 Bremen Germany Editorial Board S.Axler K.A.Ribet Mathematics Department Department of Mathematics San Francisco State University of California University at Berkeley San Francisco,CA 94132 Berkeley,CA 94720-3840 USA USA [email protected] [email protected] Mathematics Subject Classification 2000: 58-01,32-01 Library ofCongress Control Number: 2007935275 ISBN:978-0-387-90419-0 Printed on acid-free paper. © 2008 Springer Science+Business Media,LLC All rights reserved.This work may not be translated or copied in whole or in part without the written permission ofthe publisher (Springer Science+Business Media,LLC,233 Spring Street, New York,NY 10013,USA),except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation,computer software,or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication oftrade names,trademarks,service marks,and similar terms,even if they are not identified as such,is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. 9 8 7 6 5 4 3 2 1 springer.com PREFACE TO THE FIRST EDITION Thisbookisanoutgrowthandaconsiderableexpansionoflecturesgiven at Brandeis University in 1967–1968 and at Rice University in 1968–1969. The first four chapters are an attempt to survey in detail some recent developments in four somewhat different areas of mathematics: geometry (manifolds and vector bundles), algebraic topology, differential geometry, and partial differential equations. In these chapters, I have developed vari- ous tools that are useful in the study of compact complex manifolds. My motivation for the choice of topics developed was governed mainly by the applications anticipated in the last two chapters. Two principal top- ics developed include Hodge’s theory of harmonic integrals and Kodaira’s characterization of projective algebraic manifolds. This book should be suitable for a graduate level course on the general topic of complex manifolds. I have avoided developing any of the theory of several complex variables relating to recent developments in Stein manifold theory because there are several recent texts on the subject (Gunning and Rossi, Hörmander). The text is relatively self-contained and assumes famil- iarity with the usual first year graduate courses (including some functional analysis), but since geometry is one of the major themes of the book, it is developed from first principles. Each chapter is prefaced by a general survey of its content. Needless to say, there are numerous topics whose inclusion in this book would have been appropriate and useful. However, this book is not a treatise, but an attempt to follow certain threads that interconnect various fields and to culminate with certain key results in the theory of compact complex manifolds. In almost every chapter I give formal statements of theorems which are understandable in context, but whose proof oftentimes involves additional machinery not developed here (e.g., the Hirzebruch Riemann- RochTheorem);hopefully,theinterestedreaderwillbesufficientlyprepared (and perhaps motivated) to do further reading in the directions indicated. v vi Preface to the First Edition Text references of the type (4.6) refer to the 6th equation (or theorem, lemma, etc.) in Sec. 4 of the chapter in which the reference appears. If the reference occurs in a different chapter, then it will be prefixed by the Roman numeral of that chapter, e.g., (II.4.6.). Iwouldliketoexpressappreciationandgratitudetomanyofmycolleagues and friends with whom I have discussed various aspects of the book during itsdevelopment.InparticularIwouldliketomentionM.F.Atiyah,R.Bott, S. S. Chern, P. A. Griffiths, R. Harvey, L. Hörmander, R. Palais, J. Polking, O. Riemenschneider, H. Rossi, and W. Schmid whose comments were all very useful. The help and enthusiasm of my students at Brandeis and Rice during the course of my first lectures, had a lot to do with my continuing the project. M. Cowen and A. Dubson were very helpful with their careful reading of the first draft. In addition, I would like to thank two of my students for their considerable help. M. Windham wrote the first three chapters from my lectures in 1968–69 and read the first draft. Without his notes,thebookalmostsurelywouldnothavebeenstarted.J.Drouilhetread the final manuscript and galley proofs with great care and helped eliminate numerous errors from the text. IwouldliketothanktheInstituteforAdvancedStudyfortheopportunity to spend the year 1970–71 at Princeton, during which time I worked on the book and where a good deal of the typing was done by the excellent Institute staff. Finally, the staff of the Mathematics Department at Rice University was extremely helpful during the preparation and editing of the manuscript for publication. Houston Raymond O. Wells, Jr. December 1972 PREFACE TO THE SECOND EDITION In this second edition I have added a new section on the classical finite- dimensional representation theory for sl(2,C). This is then used to give a natural proof of the Lefschetz decomposition theorem, an observation first made by S. S. Chern. H. Hecht observed that the Hodge ∗-operator is essentiallyarepresentationoftheWeylreflectionoperatoractingonsl(2,C) andthisfactleadstonewproofs(duetoHecht)ofsomeofthebasicKähler identities which we incorporate into a completely revised Chapter V. The remainder of the book is generally the same as the first edition, except that numerous errors in the first edition have been corrected, and various examples have been added throughout. I would like to thank my many colleagues who have commented on the firstedition,whichhelpedagreatdealingettingridoferrors.Also,Iwould like to thank the graduate students at Rice who went carefully through the book with me in a seminar. Finally, I am very grateful to David Yingst and David Johnson who both collated errors, made many suggestions, and helped greatly with the editing of this second edition. Houston Raymond O. Wells, Jr. July 1979 vii PREFACE TO THE THIRD EDITION In the almost four decades since the first edition of this book appeared, many of the topics treated there have evolved in a variety of interesting manners.Inboththe1973and1980editionsofthisbook,onefindsthefirst fourchapters(vectorbundles,sheaftheory,differentialgeometryandelliptic partial differential equations) being used as fundamental tools for solving difficult problems in complex differential geometry in the final two chapters (namely the development of Hodge theory, Kodaira’s embedding theorem, and Griffiths’ theory of period matrix domains). In this new edition of the book, I have not changed the contents of these six chapters at all, as they have proved to be good building blocks for many other mathematical developments during these past decades. I have asked my younger colleague Oscar García-Prada to add an Appendix to this edition which highlights some aspects of mathematical developments over the past thirty years which depend substantively on the tools developed in the first six chapters. The title of the Appendix, “Moduli spaces and geometric structures” and its introduction gives the reader a good overview to what is covered in this appendix. Theobjectofthisappendixistoreportonsometopicsincomplexgeome- trythathavebeendevelopedsincethebook’ssecondeditionappearedabout 25 years ago. During this period there have been many important devel- opments in complex geometry, which have arisen from the extremely rich interaction between this subject and different areas of mathematics and theoretical physics: differential geometry, algebraic geometry, global analy- sis, topology, gauge theory, string theory, etc. The number of topics that could be treated here is thus immense, including Calabi-Yau manifolds and mirror symmetry, almost-complex geometry and symplectic mani- folds, Gromov-Witten theory, Donaldson and Seiberg-Witten theory, to mention just a few, providing material for several books (some already written). ix x Preface to the Third Edition However, since already the original scope of the book was not to be a treatise, “but an attempt to follow certain threads that interconnect various fields and to culminate with certain key results in the theory of compact complex manifolds…”, as I said in the Preface to the first edition, in the Appendixwehavechosentofocusonaparticularsetoftopicsinthetheory of moduli spaces and geometric structures on Riemann surfaces. This is a subject which has played a central role in complex geometry in the last 25 years, and which, very much in the spirit of the book, reflects another instanceofthepowerfulinteractionbetweendifferentialanalysis(differential geometryandpartialdifferentialequations),algebraictopologyandcomplex geometry. In choosing the topic, we have also taken into account that the book provides much of the background material needed (Chern classes, theory of connections on Hermitian vector bundles, Sobolev spaces, index theory, sheaf theory, etc.), making the appendix (in combination with the book) essentially self-contained. Itismyhopethatthisbookwillcontinuetobeusefulformathematicians for some time to come, and I want to express my gratitude to Springer- Verlag for undertaking this new edition and for their patience in waiting for our revision and the new Appendix. One note to the reader: the Subject Index and the Author Index of the book refer to the original six chapters of this book and not to the new Appendix (which has its own bibliographical references). Finally, I want to thank Oscar García-Prada so very much for the painstaking care and elegance in which he has summarized some of the most exciting results in the past years concerning the moduli spaces of vector bundles and Higgs’ fields, their relation to representations of the fundamental group of a compact Riemann surface (or more generally of a compact Kähler manifold) in Lie groups, and to the solutions of differen- tial equations which have their roots in the classical Laplace and Einstein equations, yielding a type of non-Abelian Hodge theory. Bremen Raymond O. Wells, Jr. June 2007 CONTENTS Chapter I Manifolds and Vector Bundles 1 1. Manifolds 2 2. Vector Bundles 12 3. Almost Complex Manifolds and the ∂¯-Operator 27 Chapter II Sheaf Theory 36 1. Presheaves and Sheaves 36 2. Resolutions of Sheaves 42 3. Cohomology Theory 51 4. Cˇech Cohomology with Coefficients in a Sheaf 63 Chapter III Differential Geometry 65 1. Hermitian Differential Geometry 65 2. The Canonical Connection and Curvature of a Hermitian Holomorphic Vector Bundle 77 3. Chern Classes of Differentiable Vector Bundles 84 4. Complex Line Bundles 97 xi