Introduction to Algebraic Geometry

GRADUATE STUDIES IN MATHEMATICS 188

Steven Dale Cutkosky 10.1090/gsm/188

GRADUATE STUDIES IN MATHEMATICS 188

Introduction to Algebraic Geometry

Steven Dale Cutkosky EDITORIAL COMMITTEE Dan Abramovich Daniel S. Freed (Chair) Gigliola Staﬃlani Jeﬀ A. Viaclovsky

2010 Mathematics Subject Classiﬁcation. Primary 14-01.

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Library of Congress Cataloging-in-Publication Data Names: Cutkosky, Steven Dale, author. Title: Introduction to algebraic geometry / Steven Dale Cutkosky. Other titles: Algebraic geometry Description: Providence, Rhode Island : American Mathematical Society, [2018] | Series: Gradu- ate studies in mathematics ; volume 188 | Includes bibliographical references and index. Identiﬁers: LCCN 2017045552 | ISBN 9781470435189 (alk. paper) Subjects: LCSH: Geometry, Algebraic. | AMS: Algebraic geometry – Instructional exposition (textbooks, tutorial papers, etc.). msc Classiﬁcation: LCC QA564 .C8794 2018 | DDC 516.3/5–dc23 LC record available at https://lccn.loc.gov/2017045552

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Contents

Preface xi

Chapter 1. A Crash Course in Commutative Algebra 1 §1.1. Basic algebra 1 §1.2. Field extensions 6 §1.3. Modules 8 §1.4. Localization 9 §1.5. Noetherian rings and factorization 10 §1.6. Primary decomposition 13 §1.7. Integral extensions 16 §1.8. Dimension 19 §1.9. Depth 20 §1.10. Normal rings and regular rings 22

Chapter 2. Affine Varieties 27 §2.1. Affine space and algebraic sets 27 §2.2. Regular functions and regular maps of affine algebraic sets 33 §2.3. Finite maps 40 §2.4. Dimension of algebraic sets 42 §2.5. Regular functions and regular maps of quasi-affine varieties 48 §2.6. Rational maps of affine varieties 58

Chapter 3. Projective Varieties 63 §3.1. Standard graded algebras 63

v vi Contents

§3.2. Projective varieties 67 §3.3. Grassmann varieties 73 §3.4. Regular functions and regular maps of quasi-projective varieties 74

Chapter 4. Regular and Rational Maps of Quasi-projective Varieties 87 §4.1. Criteria for regular maps 87 §4.2. Linear isomorphisms of projective space 90 §4.3. The Veronese embedding 91 §4.4. Rational maps of quasi-projective varieties 93 §4.5. Projection from a linear subspace 95

Chapter 5. Products 99 §5.1. Tensor products 99 §5.2. Products of varieties 101 §5.3. The Segre embedding 105 §5.4. Graphs of regular and rational maps 106

Chapter 6. The Blow-up of an Ideal 111 §6.1. The blow-up of an ideal in an aﬃne variety 111 §6.2. The blow-up of an ideal in a projective variety 120

Chapter 7. Finite Maps of Quasi-projective Varieties 127 §7.1. Aﬃne and ﬁnite maps 127 §7.2. Finite maps 131 §7.3. Construction of the normalization 135

Chapter 8. Dimension of Quasi-projective Algebraic Sets 139 §8.1. Properties of dimension 139 §8.2. The theorem on dimension of ﬁbers 141

Chapter 9. Zariski’s Main Theorem 147

Chapter 10. Nonsingularity 153 §10.1. Regular parameters 153 §10.2. Local equations 155 §10.3. The tangent space 156 §10.4. Nonsingularity and the singular locus 159 §10.5. Applications to rational maps 165 Contents vii

§10.6. Factorization of birational regular maps of nonsingular surfaces 168 §10.7. Projective embedding of nonsingular varieties 170 §10.8. Complex manifolds 175 Chapter 11. Sheaves 181 §11.1. Limits 181 §11.2. Presheaves and sheaves 185 §11.3. Some sheaves associated to modules 196 §11.4. Quasi-coherent and coherent sheaves 200 §11.5. Constructions of sheaves from sheaves of modules 204 §11.6. Some theorems about coherent sheaves 209 Chapter 12. Applications to Regular and Rational Maps 221 §12.1. Blow-ups of ideal sheaves 221 §12.2. Resolution of singularities 225 §12.3. Valuations in algebraic geometry 228 §12.4. Factorization of birational maps 232 §12.5. Monomialization of maps 236 Chapter 13. Divisors 239 §13.1. Divisors and the class group 240 §13.2. The sheaf associated to a divisor 242 §13.3. Divisors associated to forms 249 §13.4. Calculation of some class groups 249 §13.5. The class group of a curve 254 §13.6. Divisors, rational maps, and linear systems 259 §13.7. Criteria for closed embeddings 264 §13.8. Invertible sheaves 269 §13.9. Transition functions 271 Chapter 14. Differential Forms and the Canonical Divisor 279 §14.1. Derivations and Kähler differentials 279 §14.2. Differentials on varieties 283 §14.3. n-forms and canonical divisors 286 Chapter 15. Schemes 289 §15.1. Subschemes of varieties, schemes, and Cartier divisors 289 §15.2. Blow-ups of ideals and associated graded rings of ideals 293 viii Contents

§15.3. Abstract algebraic varieties 295 §15.4. Varieties over nonclosed fields 296 §15.5. General schemes 296 Chapter 16. The Degree of a Projective Variety 299 Chapter 17. Cohomology 307 §17.1. Complexes 307 §17.2. Sheaf cohomology 308 §17.3. Cechˇ cohomology 310 §17.4. Applications 312 §17.5. Higher direct images of sheaves 320 §17.6. Local cohomology and regularity 325 Chapter 18. Curves 333 §18.1. The Riemann-Roch inequality 334 §18.2. Serre duality 335 §18.3. The Riemann-Roch theorem 340 §18.4. The Riemann-Roch problem on varieties 343 §18.5. The Hurwitz theorem 345 §18.6. Inseparable maps of curves 348 §18.7. Elliptic curves 351 §18.8. Complex curves 358 §18.9. Abelian varieties and Jacobians of curves 360 Chapter 19. An Introduction to Intersection Theory 365 §19.1. Definition, properties, and some examples of intersection numbers 366 §19.2. Applications to degree and multiplicity 375 Chapter 20. Surfaces 379 §20.1. The Riemann-Roch theorem and the Hodge index theorem on a surface 379 §20.2. Contractions and linear systems 383 Chapter 21. Ramification and Etale´ Maps 391 §21.1. Norms and Traces 392 §21.2. Integral extensions 393 §21.3. Discriminants and ramification 398 Contents ix

§21.4. Ramification of regular maps of varieties 406 §21.5. Completion 408 §21.6. Zariski’s main theorem and Zariski’s subspace theorem 413 §21.7. Galois theory of varieties 421 §21.8. Derivations and Kähler differentials redux 424 §21.9. Etale´ maps and uniformizing parameters 426 §21.10. Purity of the branch locus and the Abhyankar-Jung theorem 433 §21.11. Galois theory of local rings 438 §21.12. A proof of the Abhyankar-Jung theorem 441 Chapter 22. Bertini’s Theorems and General Fibers of Maps 451 §22.1. Geometric integrality 452 §22.2. Nonsingularity of the general fiber 454 §22.3. Bertini’s second theorem 457 §22.4. Bertini’s first theorem 458 Bibliography 469 Index 477

Preface

This book is an introductory course in algebraic geometry, proving most of the fundamental classical results of algebraic geometry. Algebraic geometry combines the intuition of geometry with the preci- sion of algebra. Starting with geometric concepts, we introduce machinery as necessary to model important ideas from algebraic geometry and to prove fundamental results. Emphasis is put on developing facility with connect- ing geometric and algebraic concepts. Examples are constructed or cited illustrating the scope of these results. The theory in this book is developed in increasing sophistication, giving (and refining) definitions as required to accommodate new geometric ideas. We work as much as possible with quasi-projective varieties over an algebraically closed field of arbitrary characteristic. This allows us to inter- pret varieties through their function fields. This approach and the use of methods of algebraic number theory in algebraic geometry have been cen- tral to algebraic geometry at least since the time of Dedekind and Weber (Theorie der algebraischen Functionen einer Veränderlichen [46], translated in [47]). By interpreting the geometric concept of varieties through their regular functions, we are able to use the techniques of commutative algebra. Differences between the theory in characteristic 0 and positive characteristic are emphasized in this book. We extend our view to schemes, al- lowing rings with nilpotents, to study fibers of regular maps and to develop intersection theory. We discuss the cases of nonclosed ground fields and nonseparated schemes and some of the extra considerations which appear in these situations. A list of exercises is given at the end of many sections and chapters.

xi xii Preface

The classic textbooks Basic Algebraic Geometry [136] by Shafarevich, Introduction to Algebraic Geometry [116] by Mumford, and Algebraic Geometry [73] by Hartshorne, as well as the works of Zariski, Abhyankar, Serre, and Grothendieck, have been major influences on this book. The necessary commutative algebra is introduced and reviewed, beginning with Chapter 1, “A Crash Course in Commutative Algebra”. We state definitions and theorems, explain concepts, and give examples from commutative algebra for everything that we will need, proving some results and giving a few examples, but mostly giving references to books on commutative algebra for proofs. As such, this book is intended to be self-contained, although a reader may be curious about the proofs for some cited results in commutative algebra and will want to either derive them or look up the references. We give references to several books, mostly depending on which book has the exact statement we require. A reader should be familiar with the material through Section 1.6 on primary decomposition before beginning Chapter 2 on affine varieties. De- pending on the background of students, the material in Chapter 1 can be skipped, quickly reviewed at the beginning of a course, or be used as an outline of a semester-long course in commutative algebra before beginning the study of geometry in Chapter 2. Chapters 2–10 give a one-semester introduction to algebraic geometry, through affine and projective varieties. The sections on integral extensions, dimension, depth, and normal and regular local rings in Chapter 1 can be referred to as necessary as these concepts are encountered within a geometric context. Chapters 11–20 provide a second-semester course, which includes sheaves, schemes, cohomology, divisors, intersection theory, and the appli- cation of these concepts to curves and surfaces. Chapter 21 (on ramification and étale maps) and Chapter 22 (on Bertini’s theorems and general fibers of maps) could be the subject of a topics course for a third-semester course. The distinctions between characteristic 0 and positive characteristic are especially explored in these last chapters. These two chapters could be read any time after the completion of Chapter 14. I thank the students of my classes, especially Razieh Ahmadian, Navaneeth Chenicheri Chathath, Suprajo Das, Arpan Dutta, Melissa Emory, Kyle Maddox, Smita Praharaj, Thomas Polstra, Soumya Sanyal, Pham An Vinh, and particularly Roberto Núñez, for their feedback and helpful com- ments on preliminary versions of this book. I thank Maya Cutkosky for help with the figures. Bibliography

[1] S. Abhyankar, On the ramification of algebraic functions,Amer.J.Math.77 (1955), 575– 592, DOI 10.2307/2372643. MR0071851 [2] S. Abhyankar, Local uniformization on algebraic surfaces over ground fields of characteristic p =0,Ann.ofMath.(2) 63 (1956), 491–526, DOI 10.2307/1970014. MR0078017 [3] S. Abhyankar, On the valuations centered in a local domain,Amer.J.Math.78 (1956), 321–348, DOI 10.2307/2372519. MR0082477 [4] S. S. Abhyankar, Resolution of singularities of embedded algebraic surfaces, 2nd ed., Springer Monographs in Mathematics, Springer-Verlag, Berlin, 1998. MR1617523 [5] S. Abhyankar, On Macaulay’s examples, Notes by A. Sathaye, Conference on Commutative Algebra (Univ. Kansas, Lawrence, Kan., 1972), pp. 1–16. Lecture Notes in Math., Vol. 311, Springer, Berlin, 1973. MR0466156 [6] S. Abhyankar, Ramification theoretic methods in algebraic geometry, Annals of Mathematics Studies, no. 43, Princeton University Press, Princeton, N.J., 1959. MR0105416 [7] S. S. Abhyankar, Algebraic geometry for scientists and engineers, Mathematical Surveys and Monographs, vol. 35, American Mathematical Society, Providence, RI, 1990. MR1075991 [8] S. S. Abhyankar, Resolution of singularities and modular Galois theory, Bull. Amer. Math. Soc. (N.S.) 38 (2001), no. 2, 131–169, DOI 10.1090/S0273-0979-00-00892-2. MR1816069 [9]D.Abramovich,K.Karu,K.Matsuki,andJ.W lodarczyk, Torification and factorization of birational maps,J.Amer.Math.Soc.15 (2002), no. 3, 531–572, DOI 10.1090/S0894-0347- 02-00396-X. MR1896232 [10] K. Matsuki, Correction: “A note on the factorization theorem of toric birational maps after Morelli and its toroidal extension” [Tohoku Math. J. (2) 51 (1999), no. 4, 489–537; MR1725624 (2000i:14073)] by D. Abramovich, K. Matsuki, and S. Rashid, Tohoku Math. J. (2) 52 (2000), no. 4, 629–631, DOI 10.2748/tmj/1178207758. MR1793939 [11] M. Artin, Some numerical criteria for contractability of curves on algebraic surfaces,Amer. J. Math. 84 (1962), 485–496, DOI 10.2307/2372985. MR0146182 [12] M. Artin, Néron Models, Chapter VIII of Arithmetic Geometry, edited by G. Cornell and J. H. Silverman, Springer Verlag, 1986. MR0861977 [13] M. F. Atiyah and I. G. Macdonald, Introduction to commutative algebra, Addison-Wesley Publishing Co., Reading, Mass.-London-Don Mills, Ont., 1969. MR0242802 [14] M. Auslander, On the purity of the branch locus,Amer.J.Math.84 (1962), 116–125, DOI 10.2307/2372807. MR0137733

469 470 Bibliography

[15] M. Auslander and D. A. Buchsbaum, Unique factorization in regular local rings,Proc.Nat. Acad. Sci. U.S.A. 45 (1959), 733–734. MR0103906 [16] W. P. Barth, K. Hulek, C. A. M. Peters, and A. Van de Ven, Compact complex surfaces, 2nd ed., Ergebnisse der Mathematik und ihrer Grenzgebiete. 3. Folge. A Series of Modern Surveys in Mathematics [Results in Mathematics and Related Areas. 3rd Series. A Series of Modern Surveys in Mathematics], vol. 4, Springer-Verlag, Berlin, 2004. MR2030225 [17] D. Bayer and D. Mumford, What can be computed in algebraic geometry?, Computational algebraic geometry and commutative algebra (Cortona, 1991), Sympos. Math., XXXIV, Cambridge Univ. Press, Cambridge, 1993, pp. 1–48. MR1253986 [18] A. Beauville, Complex algebraic surfaces, London Mathematical Society Lecture Note Series, vol. 68, Cambridge University Press, Cambridge, 1983. Translated from the French by R. Barlow, N. I. Shepherd-Barron and M. Reid. MR732439 [19] E. Bertini, Introduzione alla geometria proiettiva degli iperspazi, Enrico Spoerri, Pisa, 1907. [20] C. Birkar, P. Cascini, C. D. Hacon, and J. McKernan, Existence of minimal models for varieties of log general type,J.Amer.Math.Soc.23 (2010), no. 2, 405–468, DOI 10.1090/S0894- 0347-09-00649-3. MR2601039 [21] Bhargav Bhatt, Javier Carvajal-Rojas, Patrick Grant, Karl Schwede and Kevin Tucker, Etale´ fundamental groups of strongly F-regular schemes, arXiv:1611.03884. [22] E. Bierstone and P. D. Milman, Canonical desingularization in characteristic zero by blowing up the maximum strata of a local invariant, Invent. Math. 128 (1997), no. 2, 207–302, DOI 10.1007/s002220050141. MR1440306 [23] N. Bourbaki, Commutative algebra. Chapters 1–7, Elements of Mathematics (Berlin), Springer-Verlag, Berlin, 1998. Translated from the French; Reprint of the 1989 English translation. MR1727221 [24] A. M. Bravo, S. Encinas, and O. Villamayor U., A simplified proof of desingularization and applications, Rev. Mat. Iberoamericana 21 (2005), no. 2, 349–458, DOI 10.4171/RMI/425. MR2174912 [25] A. Bravo and O. Villamayor U., Singularities in positive characteristic, stratification and simplification of the singular locus, Adv. Math. 224 (2010), no. 4, 1349–1418, DOI 10.1016/j.aim.2010.01.005. MR2646300 [26] E. Brieskorn and H. Knörrer, Plane algebraic curves,ModernBirkhäuser Classics, Birkhäuser/Springer Basel AG, Basel, 1986. Translated from the German original by John Stillwell; [2012] reprint of the 1986 edition. MR2975988 [27] M. P. Brodmann and R. Y. Sharp, Local cohomology, 2nd ed., An algebraic introduction with geometric applications, Cambridge Studies in Advanced Mathematics, vol. 136, Cambridge University Press, Cambridge, 2013. MR3014449 [28] W. Bruns and J. Herzog, Cohen-Macaulay rings, Cambridge Studies in Advanced Mathe- matics, vol. 39, Cambridge University Press, Cambridge, 1993. MR1251956 [29] C. Christensen, Strong domination/weak factorization of three-dimensional regular local rings,J.IndianMath.Soc.(N.S.)45 (1981), no. 1-4, 21–47 (1984). MR828858 [30] I. S. Cohen, On the structure and ideal theory of complete local rings,Trans.Amer.Math. Soc. 59 (1946), 54–106, DOI 10.2307/1990313. MR0016094 [31] V. Cossart and O. Piltant, Resolution of singularities of arithmetic threefolds,arXiv: 1412.0868. [32] D. Cox, J. Little, and D. O’Shea, Ideals, varieties, and algorithms, 3rd ed., An introduction to computational algebraic geometry and commutative algebra, Undergraduate Texts in Mathematics, Springer, New York, 2007. MR2290010 [33] S. D. Cutkosky, Local monomialization and factorization of morphisms (English, with Eng- lish and French summaries), Astérisque 260 (1999), vi+143. MR1734239 [34] S. D. Cutkosky, Monomialization of morphisms from 3-folds to surfaces, Lecture Notes in Mathematics, vol. 1786, Springer-Verlag, Berlin, 2002. MR1927974 Bibliography 471

[35] S. D. Cutkosky, Resolution of singularities, Graduate Studies in Mathematics, vol. 63, Amer- ican Mathematical Society, Providence, RI, 2004. MR2058431 [36] S. D. Cutkosky, Local monomialization of transcendental extensions (English, with Eng- lish and French summaries), Ann. Inst. Fourier (Grenoble) 55 (2005), no. 5, 1517–1586. MR2172273 [37] S. D. Cutkosky, Toroidalization of dominant morphisms of 3-folds,Mem.Amer.Math.Soc. 190 (2007), no. 890, vi+222, DOI 10.1090/memo/0890. MR2356202 [38] S. D. Cutkosky, Resolution of singularities for 3-folds in positive characteristic,Amer.J. Math. 131 (2009), no. 1, 59–127, DOI 10.1353/ajm.0.0036. MR2488485 [39] S. D. Cutkosky, A simpler proof of toroidalization of morphisms from 3-folds to surfaces (English, with English and French summaries), Ann. Inst. Fourier (Grenoble) 63 (2013), no. 3, 865–922, DOI 10.5802/aif.2779. MR3137475 [40] S. D. Cutkosky, Counterexamples to local monomialization in positive characteristic,Math. Ann. 362 (2015), no. 1-2, 321–334, DOI 10.1007/s00208-014-1114-7. MR3343880 [41] S. D. Cutkosky, Ramification of valuations and local rings in positive characteristic, Comm. Algebra 44 (2016), no. 7, 2828–2866, DOI 10.1080/00927872.2015.1065845. MR3507154 [42] S. D. Cutkosky, Asymptotic multiplicities of graded families of ideals and linear series,Adv. Math. 264 (2014), 55–113, DOI 10.1016/j.aim.2014.07.004. MR3250280 [43] S. D. Cutkosky and O. Piltant, Ramification of valuations, Adv. Math. 183 (2004), no. 1, 1–79, DOI 10.1016/S0001-8708(03)00082-3. MR2038546 [44] S. D. Cutkosky and V. Srinivas, On a problem of Zariski on dimensions of linear systems, Ann. of Math. (2) 137 (1993), no. 3, 531–559, DOI 10.2307/2946531. MR1217347 [45] S. D. Cutkosky and H. Srinivasan, Factorizations of birational extensions of local rings, Illinois J. Math. 51 (2007), no. 1, 41–56. MR2346185 [46] R. Dedekind and H. Weber, Theorie der algebraischen Functionen einer Veränderlichen (German), J. Reine Angew. Math. 92 (1882), 181–290, DOI 10.1515/crll.1882.92.181. MR1579901 [47] R. Dedekind and H. Weber, Theory of algebraic functions of one variable, translated from the 1882 German original and with an introduction, bibliography and index by John Stillwell, History of Mathematics, vol. 39, American Mathematical Society, Providence, RI; London Mathematical Society, London, 2012. MR2962951 [48] P. Del Pezzo, Sulle Superficie di ordine n immerse nello spazio di n +1 dimensioni, Rend. Circ.Mat.Palermo1 (1886). [49] S. Eilenberg and N. Steenrod, Foundations of algebraic topology, Princeton University Press, Princeton, New Jersey, 1952. MR0050886 [50] D. Eisenbud, Commutative algebra, With a view toward algebraic geometry, Graduate Texts in Mathematics, vol. 150, Springer-Verlag, New York, 1995. MR1322960 [51] D. Eisenbud and S. Goto, Linear free resolutions and minimal multiplicity,J.Algebra88 (1984), no. 1, 89–133, DOI 10.1016/0021-8693(84)90092-9. MR741934 [52] D. Eisenbud and J. Harris, On varieties of minimal degree (a centennial account), Algebraic geometry, Bowdoin, 1985 (Brunswick, Maine, 1985), Proc. Sympos. Pure Math., vol. 46, Amer. Math. Soc., Providence, RI, 1987, pp. 3–13, DOI 10.1090/pspum/046.1/927946. MR927946 [53] D. Eisenbud and J. Harris, The geometry of schemes, Graduate Texts in Mathematics, vol. 197, Springer-Verlag, New York, 2000. MR1730819 [54] S. Encinas and H. Hauser, Strong resolution of singularities in characteristic zero, Comment. Math. Helv. 77 (2002), no. 4, 821–845, DOI 10.1007/PL00012443. MR1949115 [55] H. Flenner, L. O’Carroll, and W. Vogel, Joins and intersections, Springer Monographs in Mathematics, Springer-Verlag, Berlin, 1999. MR1724388 472 Bibliography

[56] G. Frey and M. Jarden, Approximation theory and the rank of abelian varieties over large algebraic fields, Proc. London Math. Soc. (3) 28 (1974), 112–128, DOI 10.1112/plms/s3- 28.1.112. MR0337997 [57] W. Fulton, Intersection theory, Ergebnisse der Mathematik und ihrer Grenzgebiete (3) [Results in Mathematics and Related Areas (3)], vol. 2, Springer-Verlag, Berlin, 1984. MR732620 [58] A. M. Gabrièlov, The formal relations between analytic functions (Russian), Funkcional. Anal. i Priloˇzen. 5 (1971), no. 4, 64–65. MR0302930 [59] R. Godement, Topologie algébrique et théorie des faisceaux (French), Actualités Sci. Ind. No. 1252. Publ. Math. Univ. Strasbourg. No. 13, Hermann, Paris, 1958. MR0102797 [60] S. Goto, K. Nishida and K. Watanabe, Non-Cohen–Macaulay symbolic blow-ups for space monomial curves and counter-examples to Cowsik’s question, Proc. Amer. Math. Soc. 120 (1994), 383-392. MR1163334 (94d:13005) [61] H. Grauert, Uber¨ Modifikationen und exzeptionelle analytische Mengen (German), Math. Ann. 146 (1962), 331–368, DOI 10.1007/BF01441136. MR0137127 [62] P. Griffiths and J. Harris, Principles of algebraic geometry, Pure and Applied Mathematics, Wiley-Interscience [John Wiley & Sons], New York, 1978. MR507725 [63] A. Grothendieck, Sur quelques points d’algèbre homologique (French), Tôhoku Math. J. (2) 9 (1957), 119–221, DOI 10.2748/tmj/1178244839. MR0102537 [64] A. Grothendieck, Cohomologie locale des faisceaux cohérents et théorèmes de Lefschetz locaux et globaux (SGA 2) (French), Augmentéd’unexposéparMichèle Raynaud; Séminaire de Géométrie Algébrique du Bois-Marie, 1962; Advanced Studies in Pure Mathematics, Vol. 2, North-Holland Publishing Co., Amsterdam; Masson & Cie, Editeur,´ Paris, 1968. MR0476737 [65] A. Grothendieck and J. Dieudonńe, El´´ ements de Géométrie Algébrique I, Publ. Math. I.H.E.S. 4 (1960). [66] A. Grothendieck and J. Dieudonńe, El´´ ements de Géométrie Algébrique II, Publ. Math. I.H.E.S. 8 (1961). [67] A. Grothendieck and J. Dieudonńe, El´´ ements de Géométrie Algbrique´ III, Publ. Math. I.H.E.S. 11 (1961) and 17 (1963). [68] A. Grothendieck and J. Diudonńe, El´´ ements de Géométrie Algébrique IV, Publ. Math. I.H.E.S. 20 (1964), 24 (1965), 28 (1966), 32 (1967). [69] A. Grothendieck and J. A. Dieudonné, Eléments de géométrie algébrique. I (French), Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathemat- ical Sciences], vol. 166, Springer-Verlag, Berlin, 1971. MR3075000 [70] A. Grothendieck, Revêtements étales et Groupe Fondemental, Lecture Notes in Math. 224, Springer-Verlag, Heidelberg (1971). [71] A. Grothendieck and J. P. Murre, The tame fundamental group of a formal neighbourhood of a divisor with normal crossings on a scheme, Lecture Notes in Mathematics, Vol. 208, Springer-Verlag, Berlin-New York, 1971. MR0316453 [72] R. Hartshorne, Local cohomology, A seminar given by A. Grothendieck, Harvard University, Fall, vol. 1961, Springer-Verlag, Berlin-New York, 1967. MR0224620 [73] R. Hartshorne, Algebraic geometry, Graduate Texts in Mathematics, No. 52, Springer- Verlag, New York-Heidelberg, 1977. MR0463157 [74] R. Hartshorne, Ample subvarieties of algebraic varieties, Notes written in collaboration with C. Musili, Springer-Verlag, Berlin, Heidelberg, New York, 1970. [75] H. Hauser, On the problem of resolution of singularities in positive characteristic (or: a proof we are still waiting for), Bull. Amer. Math. Soc. (N.S.) 47 (2010), no. 1, 1–30, DOI 10.1090/S0273-0979-09-01274-9. MR2566444 Bibliography 473

[76] J. Herzog, Generators and relations of abelian semigroups and semigroup rings,Manuscripta Math. 3 (1970), 175–193, DOI 10.1007/BF01273309. MR0269762 [77] J. Herzog, A. Simis, and W. V. Vasconcelos, On the arithmetic and homology of algebras of linear type, Trans. Amer. Math. Soc. 283 (1984), no. 2, 661–683, DOI 10.2307/1999153. MR737891 [78] H. Hironaka, On the theory of birational blowing-up, ProQuest LLC, Ann Arbor, MI, 1960. Thesis (Ph.D.)–Harvard University. MR2939137 [79] H. Hironaka, Resolution of singularities of an algebraic variety over a field of characteristic zero,Ann.ofMath.(2)79 (1964), 109–326. MR0199184 [80] H. Hironaka, Three key theorems on infinitely near singularities (English, with English and French summaries), Singularités Franco-Japonaises, Sémin. Congr., vol. 10, Soc. Math. France, Paris, 2005, pp. 87–126. MR2145950 [81] W. V. D. Hodge and D. Pedoe, Methods of algebraic geometry, Cambridge, at the University Press; New York, The Macmillan Company, 1947. MR0028055 [82] C. Huneke, Determinantal ideals of linear type,Arch.Math.(Basel)47 (1986), no. 4, 324– 329, DOI 10.1007/BF01191358. MR866520 [83] C. Huneke, On the symmetric and Rees algebra of an ideal generated by a d-sequence,J. Algebra 62 (1980), no. 2, 268–275, DOI 10.1016/0021-8693(80)90179-9. MR563225 [84] N. Jacobson, Basic algebra. I, W. H. Freeman and Co., San Francisco, Calif., 1974. MR0356989 [85] H. W. E. Jung, Darstellung der Functionen eies algebraishce korrspondenzen und der ver- allgemeinerte korrespondenprrinzp, Math. Ann. 28 (1887). [86] K. Karu, Local strong factorization of toric birational maps,J.AlgebraicGeom.14 (2005), no. 1, 165–175, DOI 10.1090/S1056-3911-04-00380-7. MR2092130 [87] H. Kawanoue and K. Matsuki, Toward resolution of singularities over a field of positive characteristic (the idealistic filtration program) Part II. Basic invariants associated to the idealistic filtration and their properties, Publ. Res. Inst. Math. Sci. 46 (2010), no. 2, 359–422, DOI 10.2977/PRIMS/12. MR2722782 [88] K. S. Kedlaya, On the algebraicity of generalized power series,Beitr.AlgebraGeom.58 (2017), no. 3, 499–527, DOI 10.1007/s13366-016-0325-3. MR3683025 [89] S. L. Kleiman, Toward a numerical theory of ampleness, Ann. of Math. (2) 84 (1966), 293–344, DOI 10.2307/1970447. MR0206009 [90] J. Kollár, Lectures on resolution of singularities, Annals of Mathematics Studies, vol. 166, Princeton University Press, Princeton, NJ, 2007. MR2289519 [91] J. Kollár and S. Mori, Birational geometry of algebraic varieties, with the collaboration of C. H. Clemens and A. Corti, translated from the 1998 Japanese original, Cambridge Tracts in Mathematics, vol. 134, Cambridge University Press, Cambridge, 1998. MR1658959 [92] W. Krull, Beiträge zur Arithmetik kommutativer Integritätsbereiche. VI. Der allgemeine Diskriminantensatz. Unverzweigte Ringerweiterungen (German), Math. Z. 45 (1939), no. 1, 1–19, DOI 10.1007/BF01580269. MR1545800 [93] F.-V. Kuhlmann, Valuation theoretic and model theoretic aspects of local uniformization, Resolution of singularities (Obergurgl, 1997), Progr. Math., vol. 181, Birkhäuser, Basel, 2000, pp. 381–456. MR1748629 [94] H. Knaf and F.-V. Kuhlmann, Every place admits local uniformization in a finite extension of the function field, Adv. Math. 221 (2009), no. 2, 428–453, DOI 10.1016/j.aim.2008.12.009. MR2508927 [95] S. Lang, Algebra, 3rd ed., Graduate Texts in Mathematics, vol. 211, Springer-Verlag, New York, 2002. MR1878556 [96] S. Lang, Abelian varieties, Springer-Verlag, New York-Berlin, 1983. Reprint of the 1959 original. MR713430 474 Bibliography

[97] S. Lang and A. Néron, Rational points of abelian varieties over function fields,Amer.J. Math. 81 (1959), 95–118, DOI 10.2307/2372851. MR0102520 [98] R. Lazarsfeld, Positivity in algebraic geometry. I, Classical setting: line bundles and linear series, Ergebnisse der Mathematik und ihrer Grenzgebiete. 3. Folge. A Series of Modern Surveys in Mathematics [Results in Mathematics and Related Areas. 3rd Series. A Series of Modern Surveys in Mathematics], vol. 48, Springer-Verlag, Berlin, 2004. MR2095471 [99] R. Lazarsfeld and M. Mustat¸˘a, Convex bodies associated to linear series (English, with English and French summaries), Ann. Sci. Ec.´ Norm. Supér. (4) 42 (2009), no. 5, 783–835, DOI 10.24033/asens.2109. MR2571958 [100] J. Lipman, Rational singularities, with applications to algebraic surfaces and unique factorization, Inst. Hautes Etudes´ Sci. Publ. Math. 36 (1969), 195–279. MR0276239 [101] J. Lipman, Desingularization of two-dimensional schemes, Ann. Math. (2) 107 (1978), no. 1, 151–207. MR0491722 [102] S.Lojasiewicz, Introduction to complex analytic geometry, translated from the Polish by Maciej Klimek, Birkhäuser Verlag, Basel, 1991. MR1131081 [103] W. S. Massey, Algebraic topology: An introduction, Harcourt, Brace & World, Inc., New York, 1967. MR0211390 [104] T. Matsusaka, The theorem of Bertini on linear systems in modular fields, Mem. Coll. Sci. Univ. Kyoto Ser. A. Math. 26 (1950), 51–62, DOI 10.1215/kjm/1250778055. MR0041483 [105] H. Matsumura, Geometric structure of the cohomology rings in abstract algebraic geometry, Mem. Coll. Sci. Univ. Kyoto. Ser. A Math. 32 (1959), 33–84, DOI 10.1215/kjm/1250776697. MR0137709 [106] H. Matsumura, Commutative ring theory, translated from the Japanese by M. Reid, Cam- bridge Studies in Advanced Mathematics, vol. 8, Cambridge University Press, Cambridge, 1986. MR879273 [107] H. Matsumura, Commutative algebra, 2nd ed., Mathematics Lecture Note Series, vol. 56, Benjamin/Cummings Publishing Co., Inc., Reading, Mass., 1980. MR575344 [108] A. Micali, Sur les algèbres universelles (French), Ann. Inst. Fourier (Grenoble) 14 (1964), no. fasc. 2, 33–87. MR0177009 [109] J. S. Milne, Etale´ cohomology, Princeton Mathematical Series, vol. 33, Princeton University Press, Princeton, N.J., 1980. MR559531 [110] J. S. Milne, Abelian varieties, Arithmetic geometry (Storrs, Conn., 1984), Springer, New York, 1986, pp. 103–150. MR861974 [111] J. S. Milne, Jacobian varieties, Arithmetic geometry (Storrs, Conn., 1984), Springer, New York, 1986, pp. 167–212. MR861976 [112] S. Mori, Projective manifolds with ample tangent bundles,Ann.ofMath.(2)110 (1979), no. 3, 593–606, DOI 10.2307/1971241. MR554387 [113] S. Mori, Threefolds whose canonical bundles are not numerically effective, Ann. of Math. (2) 116 (1982), no. 1, 133–176, DOI 10.2307/2007050. MR662120 [114] S. Mori, Flip theorem and the existence of minimal models for 3-folds,J.Amer.Math.Soc. 1 (1988), no. 1, 117–253, DOI 10.2307/1990969. MR924704 [115] D. Mumford, Algebraic geometry. I. Complex projective varieties; Grundlehren der Mathe- matischen Wissenschaften, No. 221, Springer-Verlag, Berlin-New York, 1976. MR0453732 [116] D. Mumford, The red book of varieties and schemes, Springer-Verlag, 1980. [117] D. Mumford, The topology of normal singularities of an algebraic surface and a criterion for simplicity, Inst. Hautes Etudes´ Sci. Publ. Math. 9 (1961), 5–22. MR0153682 [118] D. Mumford, Lectures on curves on an algebraic surface, With a section by G. M. Bergman. Annals of Mathematics Studies, No. 59, Princeton University Press, Princeton, N.J., 1966. MR0209285 Bibliography 475

[119] D. Mumford, Abelian varieties, Tata Institute of Fundamental Research Studies in Mathe- matics, No. 5, Published for the Tata Institute of Fundamental Research, Bombay; Oxford University Press, London, 1970. MR0282985 [120] J. R. Munkres, Topology: A first course, Prentice-Hall, Inc., Englewood Cliffs, N.J., 1975. MR0464128 [121] M. Nagata, Local rings, Interscience Tracts in Pure and Applied Mathematics, No. 13, In- terscience Publishers a division of John Wiley & Sons New York-London, 1962. MR0155856 [122] M. Nagata, Lectures on the fourteenth problem of Hilbert, Tata Institute of Fundamental Research, Bombay, 1965. MR0215828 [123] T. Oda, Torus embeddings and applications, based on joint work with Katsuya Miyake, Tata Institute of Fundamental Research Lectures on Mathematics and Physics, vol. 57, Tata Institute of Fundamental Research, Bombay; by Springer-Verlag, Berlin-New York, 1978. MR546291 [124] M. Raynaud, Anneaux locaux henséliens (French), Lecture Notes in Mathematics, Vol. 169, Springer-Verlag, Berlin-New York, 1970. MR0277519 [125] D. Rees, On a problem of Zariski, Illinois J. Math. 2 (1958), 145–149. MR0095843 [126] M. Reid, Canonical 3-folds,Journées de Géometrie Algébrique d’Angers, Juillet 1979/Alge- braic Geometry, Angers, 1979, Sijthoff & Noordhoff, Alphen aan den Rijn—Germantown, Md., 1980, pp. 273–310. MR605348 [127] P. C. Roberts, A prime ideal in a polynomial ring whose symbolic blow-up is not Noetherian, Proc.Amer.Math.Soc.94 (1985), no. 4, 589–592, DOI 10.2307/2044869. MR792266 [128] J. J. Rotman, An introduction to homological algebra, Pure and Applied Mathematics, vol. 85, Academic Press, Inc. [Harcourt Brace Jovanovich, Publishers], New York-London, 1979. MR538169 [129] J. Sally, Regular overrings of regular local rings, Trans. Amer. Math. Soc. 171 (1972), 291–300, DOI 10.2307/1996383. MR0309929 [130] J. D. Sally, Numbers of generators of ideals in local rings, Marcel Dekker, Inc., New York- Basel, 1978. MR0485852 [131] P. Samuel, Algebraic theory of numbers, translated from the French by Allan J. Silberger, Houghton Mifflin Co., Boston, Mass., 1970. MR0265266 [132] J.-P. Serre, Faisceaux algébriques cohérents (French), Ann. of Math. (2) 61 (1955), 197–278, DOI 10.2307/1969915. MR0068874 [133] J.-P. Serre, Géométrie algébrique et géométrie analytique (French), Ann. Inst. Fourier, Grenoble 6 (1955), 1–42. MR0082175 [134] J.-P. Serre, Algebraic groups and class fields, translated from the French, Graduate Texts in Mathematics, vol. 117, Springer-Verlag, New York, 1988. MR918564 [135] J.-P. Serre, Local fields, translated from the French by Marvin Jay Greenberg, Graduate Texts in Mathematics, vol. 67, Springer-Verlag, New York-Berlin, 1979. MR554237 [136] I. R. Shafarevich, Basic algebraic geometry. Varieties in projective space; translated from the 1988 Russian edition and with notes by Miles Reid, 2nd ed., Springer-Verlag, Berlin, 1994. MR1328833 [137] D. L. Shannon, Monoidal transforms of regular local rings,Amer.J.Math.95 (1973), 294– 320. MR0330154 [138] A. Simis, B. Ulrich, and W. V. Vasconcelos, Cohen-Macaulay Rees algebras and degrees of polynomial relations, Math. Ann. 301 (1995), no. 3, 421–444, DOI 10.1007/BF01446637. MR1324518 [139] E. Snapper, Multiples of divisors,J.Math.Mech.8 (1959), 967–992. MR0109156 [140] B. Teissier, Valuations, deformations, and toric geometry, Valuation theory and its applications, Vol. II (Saskatoon, SK, 1999), Fields Inst. Commun., vol. 33, Amer. Math. Soc., Providence, RI, 2003, pp. 361–459. MR2018565 476 Bibliography

[141] M. Temkin, Inseparable local uniformization,J.Algebra373 (2013), 65–119, DOI 10.1016/j.jalgebra.2012.09.023. MR2995017 [142] B. L. van der Waerden, Modern Algebra. Vol. I, translated from the second revised Ger- man edition by Fred Blum; with revisions and additions by the author, Frederick Ungar Publishing Co., New York, N. Y., 1949. MR0029363 [143] B. L. van der Waerden, Modern Algebra. Vol. II, translated from the second revised Ger- man edition by Fred Blum; with revisions and additions by the author, Frederick Ungar Publishing Co., New York, N. Y., 1950. [144] R. J. Walker, Reduction of the singularities of an algebraic surface, Ann. of Math. (2) 36 (1935), no. 2, 336–365, DOI 10.2307/1968575. MR1503227 [145] A. Weil, Foundations of algebraic geometry, American Mathematical Society, Providence, R.I., 1962. MR0144898 [146] A. Weil, Variétés Abéliennes et Courbes Algébriques, Hermann, Paris, 1971. [147] J. W lodarczyk, Decomposition of birational toric maps in blow-ups & blow-downs,Trans. Amer. Math. Soc. 349 (1997), no. 1, 373–411, DOI 10.1090/S0002-9947-97-01701-7. MR1370654 [148] O. Zariski, Algebraic surfaces, Second supplemented edition, with appendices by S. S. Ab- hyankar, J. Lipman, and D. Mumford; Ergebnisse der Mathematik und ihrer Grenzgebiete, Band 61, Springer-Verlag, New York-Heidelberg, 1971. MR0469915 [149] O. Zariski, The reduction of the singularities of an algebraic surface, Ann. of Math. (2) 40 (1939), 639–689, DOI 10.2307/1968949. MR0000159 [150] O. Zariski, Local uniformization on algebraic varieties, Ann. of Math. (2) 41 (1940), 852– 896, DOI 10.2307/1968864. MR0002864 [151] O. Zariski, Pencils on an algebraic variety and a new proof of a theorem of Bertini,Trans. Amer. Math. Soc. 50 (1941), 48–70, DOI 10.2307/1989911. MR0004241 [152] O. Zariski, Foundations of a general theory of birational correspondences, Trans. Amer. Math. Soc. 53 (1943), 490–542, DOI 10.2307/1990215. MR0008468 [153] O. Zariski, Reduction of the singularities of algebraic three dimensional varieties, Ann. of Math. (2) 45 (1944), 472–542, DOI 10.2307/1969189. MR0011006 [154] O. Zariski, The concept of a simple point of an abstract algebraic variety, Trans. Amer. Math. Soc. 62 (1947), 1–52. MR0021694 [155] O. Zariski, A simple analytical proof of a fundamental property of birational transforma- tions,Proc.Nat.Acad.Sci.U.S.A.35 (1949), 62–66. MR0028056 [156] O. Zariski, Theory and applications of holomorphic functions on algebraic varieties over arbitrary ground fields,Mem.Amer.Math.Soc.,No. 5 (1951), 90. MR0041487 [157] O. Zariski, On the purity of the branch locus of algebraic functions, Proc. Nat. Acad. Sci. U.S.A. 44 (1958), 791–796. MR0095846 [158] O. Zariski, Introduction to the problem of minimal models in the theory of algebraic surfaces, Publications of the Mathematical Society of Japan, no. 4, The Mathematical Society of Japan, Tokyo, 1958. MR0097403 [159] O. Zariski, The theorem of Riemann-Roch for high multiples of an effective divisor on an algebraic surface, Ann. of Math. (2) 76 (1962), 560–615, DOI 10.2307/1970376. MR0141668 [160] O. Zariski and P. Samuel, Commutative algebra. Vol. 1, with the cooperation of I. S. Cohen; corrected reprinting of the 1958 edition; Graduate Texts in Mathematics, No. 28, Springer- Verlag, New York-Heidelberg-Berlin, 1975. MR0384768 [161] O. Zariski and P. Samuel, Commutative algebra. Vol. II, reprint of the 1960 edition; Graduate Texts in Mathematics, Vol. 29, Springer-Verlag, New York-Heidelberg, 1975. MR0389876 Index

(L1 ···Lt), 369 I(Y ), 29, 33, 69, 70, 103 (L1 ···Lt; F)V , 368 I(Z), 292 sat (L1 ···Lt · W ), 369 I ,66 (φ), 286 IX (Y ), 33, 70 (φ)X , 286 J(S/R), 435 (f), 241 Ks, 438 (f)0, 241 KX , 286 (f)∞, 242 M(n), 63 A-torsion, 208 M ∨, 243

B(I), 113, 121 M(F ),64 B(I), 221–223 M(p),64 C∗(U, F), 310 N(X), 382

D(B/A), 399 NL/K , 392 D(F ), 71, 103 P (A), 243 D(f), 48 PGX , 189 D ∩ U, 242 PM (z), 301 D ≡ 0, 382 PY , 301 i D1 ≥ D2, 240 R φ∗F, 320 (d) D1 ∼ D2, 242 R ,64 DL/K (a1,...,an), 398 S(I; R), 56 F : Xp → X, 349 S(W ), 103 F a,71 S(X), 70 Fr(x), 349 S(X × Pn), 105 G(L, K), 7 S(Y ), 105 G(Y/X), 421 S(Pm × Pn), 102 Gi(S/R), 440 S(Pn), 68 Gs(S/R), 438 T (A), 24 i ∗ H (A ), 307 TA(M), 208 i H (X, F), 308, 309 Tp(X), 157 i F HY (X, ), 330 Vν , 228 i HI (M), 326 WF , 103 0 HSing(U, G), 358 X × Y , 101 I(S/R), 435 X(r), 360

477 478 Index

XF ,71 F⊗G, 204, 206 F⊗ G XZ , 290 OX , 204, 206 an Xf ,48 F , 359 ∗ Xp, 290 G , 245 H Y , 422 IOX , 205 Z(A), 102 IY , 155, 198, 200 Z(I), 68 IZ , 289 Z(J), 70 IY,p, 155 I Z(T ), 28, 33 div(s), 291 Z(U), 68 L−1, 269 Z(f), 28 OD, 290 ∩ Z1 Z2, 290 OU (V ), 53 ZX (T ), 33 OX -module, 191 ZX (U), 70 OX -module homomorphism, 191 Zred, 289 OX -submodule, 192 [L : K]i,7 OX -torsion, 209 [L : K]s,7 OX (D), 242 Am × An , 101 OX (U), 49, 75, 187 An ,27 OX (n), 210 C{ } O∗ x1,...,xn , 176 X , 271 Δ, 176 OU,p,53 ΔX , 110 OW,(p,q), 103 ΔPn , 106 OW (U), 103 F ΓY (X, ), 330 OX,E, 240 Γν , 228 OX,Y , 229 Γφ, 106, 107 OX,p,50,75 N,1 T (F), 209 n (a ) ΩX/k, 286 p i , 245 n i Ωk(X)/k, 286 AnnX (σ), 208 ΩB/A, 280 Aut(X), 351 ΩX/k, 283 Base(L), 261 m n P × P , 102 Cl(X), 242 Pn 0 k ,67 Cl (X), 258 Z +,1 Cokernel(α), 194 Z an, 359 DerA(B, M), 279 p Hˇ (X, F), 312 Div(F ), 249 p Hˇ (U, F), 311 Div(X), 240 χ(F), 319 Grass(a, b), 73 deg x,63 Image(α), 194 deg, 250 Kernel(α), 194 deg(D), 254 Map(U, A1), 49, 75 deg(Y ), 301 Pic(X), 270 deg(φ), 254, 371, 406 Pican(X), 359 dim R,19 Proj(S), 67, 297 dim X, 42, 139 Spec(R), 5, 296 R(M), 9 Supp D, 240 Mˆ , 409 bideg(x), 102 φˆ : Rˆ → Sˆ, 411 div(φ), 286 lim← Ai, 184 div(φ)X , 286 lim→ Ai, 182 div(f), 242 F(n), 210 div(f)X , 242 Index 479

div(s), 291 mR, the maximal ideal of a local ring, 1 gcd(D0,...,Dn), 259 mp, 50, 75, 283 ht(P), 19 mX,p,50,75 reg(M), 328 n-fold, 45 reg(M˜ ), 328 p-basis, 425 trdeg L,6 p-independent, 425 K μ(I), 46 r(R : R), 443 νE , 241 Aut(L/K), 7 φ : X Y ,58,93 Aut(k(Y )/k(X)), 421 ∗ F G φ ,35,76 HomOX ( , ), 201 ∗ F G φ :Cl(Y ) → Cl(X), 252 HomOX ( , ), 204, 206 φ∗M, 205 Num(X), 382 φ−1(Z), 290 QF(R), 1 φL, 260 QR(A), 291 φV , 260 codimX (Y ), 45 √Vol(L), 345 depthI M, 326 √I,3 res, 34 gr (R), 23 I, 289 mR Tr , 392 L/K Abel, 360 I˜, 120, 198, 200 Abelian variety, 360 J˜, 192 Abhyankar, xii, 170, 227, 228, 231, 232, M˜ , 196 234, 235, 392, 413, 435 N˜, 199 Abhyankar-Jung theorem, 436 | | D , 260 Abramovich, 234 ∧n M, 286 Abstract prevariety, 295 ai(M), 327 Abstract variety, 295 d(R : R), 443 Adjunction, 287, 380 dφp, 157 Affine map, 127 e(R), 376 Affine scheme, 296 e(Si/R), 396 ∗ Affine subscheme, 289 e(ν /ν), 397 Affine subvariety, 34 eP , 346 Affine variety, 55 f(Si/R), 396 ∗ Algebraic function field, 7 f(ν /ν), 397 Algebraic local ring, 441 ∗G f , 207 Algebraic set, biprojective, 103 h f ,71 Algebraic set, in An,28 # f , 191 Algebraic set, projective, 68 f∗F , 191 Algebraic set, quasi-affine, 34 g(R : R), 443 Algebraic set, quasi-biprojective, 103 g(X), 334 Ample divisor, 262 i F h (X, ), 319 Ample invertible sheaf, 270 k, an algebraically closed field, 1 Analytic implicit function theorem, 176 k-linear Frobenius map, 349 Artin, 362 k(U), 53, 82 Auslander, 25, 433 k(W ), 103 k(X), 49, 74 Base locus, of a linear system, 261 k(p), 50, 75, 283 Base point free linear system, 261 k[X], 33 Bayer, 330 k[Am × An], 101 Bertini, 304, 451 k[An], 27 Bézout, 375 m-regular, 328 Bézout’s theorem, 375 480 Index

Bhatt, 433 Cohomology, 311, 312 Bihomogeneous coordinate ring, 102 Complete abstract variety, 295 Birational equivalence, of affine Complete linear system, 260 varieties, 60 Complex, 307 Birational equivalence, of Complex manifold, 175 quasi-projective varieties, 94 Constant sheaf, 189 Birational map, of affine varieties, 60 Coordinate functions, on an affine Birational map, of quasi-projective algebraic set, 38 varieties, 94 Coordinate ring of Pn,68 Birkar, 387 Coordinate ring, of a biprojective Blow-up, of a subvariety of a projective variety, 103 variety, 123 Coordinate ring, of a projective Blow-up, of a subvariety of an affine algebraic set, 70 variety, 113 Coordinate ring, of a subvariety of Blow-up, of an ideal of a projective Am × Pn, 105 variety, 121 Cossart, 228 Blow-up, of an ideal of an affine variety, Curve, 45 113 Cutkosky, 235, 236, 345 Blow-up, of an ideal sheaf on a projective variety, 222 Dedekind, xi Blow-up, of an ideal sheaf on a Degree, of a divisor on a curve, 254 quasi-projective variety, 223 Degree, of a graded module, 301 Blow-up, of an ideal sheaf on an affine Degree, of a map of curves, 254 variety, 221 Degree, of a projective subscheme, 301 Buchsbaum, 25 Degree, of a regular map, 371, 406 Degree, of an invertible sheaf on a Canonical divisor, 286 curve, 259 Cartier divisor, 245, 273, 291 Del Pezzo, 304 Carvajal-Rojas, 433 Derivation, 279 Cascini, 387 Diagonal, 106, 176 Castelnuovo, 328, 383 Dimension, of a quasi-projective Castelnuovo’s contraction theorem, 383 algebraic set, 139 Chain map, 307 Dimension, of a topological space, 42 Chevalier, 411 Direct limit, 181 Chinese remainder theorem, 4 Discrete valuation, 395 Christiansen, 235 Discrete valuation ring, 395 Clifford, 342 Discriminant ideal, 398 Clifford’s theorem, 342 Divisor, 240 Closed embedding, of a quasi-affine Divisor class group, 242 variety, 55 Divisor of a function, 241 Closed embedding, of a quasi-projective Divisor of a section of an invertible variety, 88 sheaf, 273 Closed embedding, of an affine algebraic Divisor of poles of a function, 242 set, 38 Divisor of zeros of a function, 241 Closed subscheme, 289 Divisor, local equation, 245 Codimension, of a quasi-affine algebraic Divisor, of a form, 249 set, 45 Divisor, of a rational differential Codimension, of a quasi-projective n-form, 286 algebraic set, 141 Divisor, support, 240 Cohen, 410 Divisorial valuation, 229 Coherent OX -module, 200 Dominant map, of affine algebraic sets, Coherent sheaf, 290 37 Index 481

Dominant rational map, of affine Hartshorne, xii, 181 varieties, 59 Heinzer, 395 Dominant rational map, of Herzog, 46, 116 quasi-projective varieties, 94 Higher direct images of a sheaf, 320 Dominant regular map, of a Hilbert, 11, 29, 301, 376 quasi-projective variety, 82 Hilbert polynomial, of a graded module, Dominate, rings, 1 301 dvr, 395 Hilbert polynomial, of a projective subscheme, 301 Effective Cartier divisor, 291 Hilbert’s basis theorem, 11 Effective divisor, 240 Hilbert’s nullstellensatz, 29 Eisenbud, 304, 330 Hilbert-Samuel polynomial, 376 Elliptic curve, 341 Hironaka, 227, 232, 234, 295 ´ Etale regular map, 426 Hodge index theorem, 382 Euclidean topology, 175 Homogeneous coordinates, 90 Euler, 13 Homogeneous coordinates, on Pn,68 Euler characteristic of a sheaf, 319 Homogeneous ideal, 64 Excision, 331 Homogeneous ideal of a subscheme, 292 Fiber cone, 294 Homotopy, 308 Finite map, 127 Huneke, 116 Finite map, of affine varieties, 40 Hurwitz, 348 First theorem of Bertini, 459 Ideal sheaf, 120, 205 Fractional ideal, 243 Ideal sheaf, of a subvariety, 200 Frobenius homomorphism, 349 Ideal sheaf, on a projective variety, 192 Gabrièlov, 420 Ideal sheaf, on an affine variety, 192 Galois over X, 422 Ideal transform, 56 Galois regular map, 422 Image, of a rational map, 94 Generated by global sections, 212 Indirect limit, 184 Genus, of a curve, 334 Inertia field, 440 Geometric regularity theorem, 328 Injective sheaf homomorphism, 194 Geometrically integral ring, 452 Integral scheme, 290 Geometrically integral scheme, 452 Intersection number, 368 Geometrically irreducible ring, 452 Invertible sheaf, 203, 223, 245, 269, 290 Geometrically irreducible scheme, 452 Irreducible scheme, 290 Geometrically reduced ring, 452 Irreducible topological space, 29 Geometrically reduced scheme, 452 Isomorphism, of affine algebraic sets, 38 Germ, 185 Isomorphism, of quasi-affine varieties, Godement, 181 54 Going down theorem, 393 Isomorphism, of varieties, 76 Going up theorem, 393 Goto, 324, 330 Jacobi, 360 Graded module, 63 Jacobian criterion for nonsingularity, Graded ring, 63 160 Grant, 433 Jacobian, of a curve, 360, 361 Graph, of a rational map, 107 Jung, 435 Graph, of a regular map, 106 Grauert, 387 Kähler differentials, 280 Grothendieck, xii, 151, 367, 433 Kaplansky, 232 Karu, 234, 236 Hacon, 387 Kollár, 387 Harris, 304 Krull, 20 482 Index

Krull’s principal ideal theorem, 20 Open subscheme, 289 Künneth, 319 Künneth formula, 319 Picard group, 270 Piltant, 228 Lang, 29 Presheaf, 185 Lazarsfeld, 345 Presheaf, homomorphism, 185 Linear equivalence of divisors, 242 Presheaf, isomorphism, 185 Linear subspace, of a projective space, Prime divisor, 240 95 Primitive element, 401 Linear system, 260 Primitive element theorem, 7 Lipman, 227, 231 Principal divisor, 242 Local cohomology, 326, 330 Projective algebraic set, 69 Local equations, 155 Projective Noether normalization, 134 Local ring, 1 Projective scheme, 297 Locally free sheaf, 217 Projective subscheme, 289 Locally principal ideal sheaf, 223 Projective variety, 69 Locally ringed space, 191 Proper transform, 123 Purity of the branch locus, 433 Map of complexes, 307 Matsuki, 234 Quadratic transform, 170 Matsusaka, 452 Quasi-affine variety, 34 Mayer-Vietoris sequence, 331 Quasi-coherent O -module, 200 McKernan, 387 X Quasi-coherent sheaf, 290 Milne, 362 Quasi-projective algebraic set, 69 Mori, 387 Quasi-projective subscheme, 289 Morphism, of affine schemes, 297 Quasi-projective variety, 69 Morphism, of locally ringed spaces, 191 Quotient of Y by H, 422 Morphism, of schemes, 297 Multiplicity, 376 Ramification index, of a regular map of Mumford, xii, 328, 330 curves, 346 Mustat¸˘a, 345 Ramification locus, in the domain of a Nagata, 57, 324, 433 finite map, 432, 433 Nakayama, 8 Ramification locus, in the range of a Newton, 437 finite map, 407 Nishida, 324 Ramified extension, of a normal Noether, 17, 134 domain, 400 Noether’s normalization lemma, 17 Ramified extension, of local domains, Nondegenerate variety, 299 399 Nonsingular point, of a variety, 160 Ramified, map of curves, 346 Nonsingular, quasi-projective variety, Rashid, 234 160 Rational function field, 7 Normal field extension, 394 Rational functions, on a biprojective Normal point, 135 variety, 103 Normal variety, 135 Rational functions, on a projective Normalization, in a finite extension, 135 variety, 74 Nullhomotopic, 308 Rational functions, on a quasi-affine Numerical equivalence of divisors, 382 variety, 53 Numerical polynomial, 300 Rational functions, on a quasi-projective variety, 82 Oda, 235 Rational functions, on an affine variety, Open embedding, of quasi-affine 49 varieties, 55 Rational map, of affine varieties, 58 Index 483

Rational map, of projective varieties, 93 Serre duality, 319, 339 Rational map, of quasi-projective Shafarevich, xii, 168 varieties, 93 Shannon, 232 Rational maps, on a subvariety of Sheaf, 186 Am × Pn, 105 Sheaf cohomology, 308 Reduced ramification index, 396 Sheaf, axioms, 186 Reduced scheme, 290 Sheaf, global section, 186 Rees, 57 Sheaf, homomorphism, 187 Reflexive rank 1 sheaf, 245 Sheaf, isomorphism, 187 Regular functions, on An,27 Sheaf, support, 203 Regular functions, on a quasi-affine Sheafification of a graded module on a variety, 49 projective variety, 199 Regular functions, on an affine Sheafification of a module on an affine algebraic set, 33 variety, 196 Regular functions, on an open subset of Sheafification of a presheaf, 187 a biprojective variety, 103 Short exact sequence of sheaves, 194 Regular map, of affine algebraic sets, 36 Simis, 116 Regular map, of an affine variety to An, Singular cohomology, 358 35 Singular locus, 162 Regular map, of quasi-affine varieties, Smooth morphism, 456 54 Snapper, 366 Regular map, of varieties, 76 Snapper polynomial, 366 Regular maps, of biprojective varieties, Splitting field, 438 103 Splitting group, 438 Regular parameters, 154 Srinivas, 345 Regularity, 328 Strict transform, of a projective variety, Relative degree, 396 123 Resolution of indeterminancy, 225 Strict transform, of an affine variety, Resolution of singularities, 225 116 Riemann, 335, 340 Subscheme, 289 Riemann-Roch inequality, 335 Subsheaf, 192 Riemann-Roch problem, 344 Subvariety, 69 Riemann-Roch theorem, 340 Surface, 45 Rigidity lemma, 358 Surjective sheaf homomorphism, 194 Roberts, 324 Symbolic power, 245 Roch, 335, 340 System of parameters, 142

Sally, 46, 232 Tamely ramified, map of curves, 346 Samuel, 376 Tangent cone, 294 Scheme, 289, 297 Tangent space, extrinsic definition, 156 Scheme-theoretic fiber, 290 Tangent space, intrinsic definition, 157 Scheme-theoretic intersection, 290 Torsion sheaf, 366 Schwede, 433 Transcendence basis, 6 Second theorem of Bertini, 458 Transcendence degree, 6 Section, nonzero divisor, 291 Transition functions on an invertible Separable field extension, 452 sheaf, 271 Separable regular map, 346, 452 Trivialization, of an invertible sheaf, 292 Separably generated field, 7 Tucker, 433 Separated scheme, 297 Separated, variety, 82 Ulrich, 116 Separating transcendence basis, 7 Uniformizing parameters, 285 Serre, xii, 301, 319, 335, 339, 468 Universal property of blowing up, 223 484 Index

Unramiﬁed extension, of a normal domain, 400 Unramiﬁed extension, of local domains, 399

Valuation, 228 Valuation ring, 228 Value group, 228 Variety, biprojective, 103 Variety, quasi-biprojective, 103 Vasconcelos, 116 Veronese subring, 64 Very ample divisor, 262 Very ample invertible sheaf, 270

Walker, 227 Watanabe, 324 Weber, xi Weierstrass, 176 Weierstrass preparation theorem, 176 Weil, 362 Wildly ramiﬁed, map of curves, 346 Wlodarczyk, 234

Zariski, xii, 76, 148, 151, 161, 168, 227, 229–232, 344, 388, 392, 413, 416, 420, 433, 452, 458 Zariski topology, on An,29 Zariski topology, on Pn,68 Zariski topology, on a quasi-projective algebraic set, 68 Zariski topology, on an aﬃne algebraic set, 34 Zariski topology, on the Proj of a graded ring, 67 Zariski topology, on the Spec of a ring, 5 Zariski’s connectedness theorem, 151 Zariski’s main theorem, 148, 416 Zariski’s subspace theorem, 420 This book presents a readable and accessible introductory course in algebraic geometry, with most of the fundamental classical results presented with complete proofs. An emphasis is placed on developing connections between geometric and algebraic aspects of the theory. Differences between the theory in characteristic 0 and positive characteristic are emphasized. The basic tools of classical and modern algebraic geometry are introduced, including varieties, schemes, singularities, sheaves, sheaf cohomology, and intersection theory. Basic classical results on curves and surfaces EVITVSZIH1SVIEHZERGIHXSTMGWWYGLEWVEQM½GEXMSRXLISV]>EVMWOM´WQEMRXLISVIQ ERH&IVXMRM´WXLISVIQWJSVKIRIVEPPMRIEVW]WXIQWEVITVIWIRXIH[MXLTVSSJWMRXLI ½REPGLETXIVW With more than 200 exercises, the book is an excellent resource for teaching and learning introductory algebraic geometry.

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