Local Algebra

ISBN-13: 9783642085901 / Angielski / Miękka / 2011 / 130 str.

Jean-Pierre Serre;C.W. Chin

Opis

The present book is an English translation of Algebre Locale - Multiplicites published by Springer-Verlag as no. 11 of the Lecture Notes series. The original text was based on a set of lectures, given at the College de France in 1957-1958, and written up by Pierre Gabriel. Its aim was to give a short account of Commutative Algebra, with emphasis on the following topics: a) Modules (as opposed to Rings, which were thought to be the only subject of Commutative Algebra, before the emergence of sheaf theory in the 1950s); b) H omological methods, a la Cartan-Eilenberg; c) Intersection multiplicities, viewed as Euler-Poincare characteristics. The English translation, done with great care by Chee Whye Chin, differs from the original in the following aspects: - The terminology has been brought up to date (e.g. "cohomological dimension" has been replaced by the now customary "depth"). I have rewritten a few proofs and clarified (or so I hope) a few more. - A section on graded algebras has been added (App. III to Chap. IV). - New references have been given, especially to other books on Commu- tive Algebra: Bourbaki (whose Chap. X has now appeared, after a 40-year wait), Eisenbud, Matsumura, Roberts, .... I hope that these changes will make the text easier to read, without changing its informal "Lecture Notes" character.

Spis treści

I. Prime Ideals and Localization.- §1. Notation and definitions.- §2. Nakayama’s lemma.- §3. Localization.- §4. Noetherian rings and modules.- §5. Spectrum.- §6. The noetherian case.- §7. Associated prime ideals.- §8. Primary decompositions.- II. Tools.- A: Filtrations and Gradings.- §1. Filtered rings and modules.- §2. Topology defined by a filtration.- §3. Completion of filtered modules.- §4. Graded rings and modules.- §5. Where everything becomes noetherian again — q -adic filtrations.- B: Hilbert-Samuel Polynomials.- §1. Review on integer-valued polynomials.- §2. Polynomial-like functions.- §3. The Hilbert polynomial.- §4. The Samuel polynomial.- III. Dimension Theory.- A: Dimension of Integral Extensions.- §1. Definitions.- §2. Cohen-Seidenberg first theorem.- §3. Cohen-Seidenberg second theorem.- B: Dimension in Noetherian Rings.- §1. Dimension of a module.- §2. The case of noetherian local rings.- §3. Systems of parameters.- C: Normal Rings.- §1. Characterization of normal rings.- §2. Properties of normal rings.- §3. Integral closure.- D: Polynomial Rings.- §1. Dimension of the ring A[X1,..., Xn].- §2. The normalization lemma.- §3. Applications. I. Dimension in polynomial algebras.- §4. Applications. II. Integral closure of a finitely generated algebra.- §5. Applications. III. Dimension of an intersection in affine space.- IV. Homological Dimension and Depth.- A: The Koszul Complex.- §1. The simple case.- §2. Acyclicity and functorial properties of the Koszul complex.- §3. Filtration of a Koszul complex.- §4. The depth of a module over a noetherian local ring.- B: Cohen-Macaulay Modules.- §1. Definition of Cohen-Macaulay modules.- §2. Several characterizations of Cohen-Macaulay modules.- §3. The support of a Cohen-Macaulay module.- §4. Prime ideals and completion.- C: Homological Dimension and Noetherian Modules.- §1. The homological dimension of a module.- §2. The noetherian case.- §3. The local case.- D: Regular Rings.- §1. Properties and characterizations of regular local rings.- §2. Permanence properties of regular local rings.- §3. Delocalization.- §4. A criterion for normality.- §5. Regularity in ring extensions.- Appendix I: Minimal Resolutions.- §1. Definition of minimal resolutions.- §2. Application.- §3. The case of the Koszul complex.- Appendix II: Positivity of Higher Euler-Poincaré Characteristics.- Appendix III: Graded-polynomial Algebras.- §1. Notation.- §2. Graded-polynomial algebras.- §3. A characterization of graded-polynomial algebras.- §4. Ring extensions.- §5. Application: the Shephard-Todd theorem.- V. Multiplicities.- A: Multiplicity of a Module.- §1. The group of cycles of a ring.- §2. Multiplicity of a module.- B: Intersection Multiplicity of Two Modules.- §1. Reduction to the diagonal.- §2. Completed tensor products.- §3. Regular rings of equal characteristic.- §4. Conjectures.- §5. Regular rings of unequal characteristic (unramified case).- §6. Arbitrary regular rings.- C: Connection with Algebraic Geometry.- §1. Tor-formula.- §2. Cycles on a non-singular affine variety.- §3. Basic formulae.- §4. Proof of theorem 1.- §5. Rationality of intersections.- §6. Direct images.- §7. Pull-backs.- §8. Extensions of intersection theory.- Index of Notation.