内容简介
The first part of this volume is based on a course taught at Princeton University in 1961-62; at that time, an excellent set of notes was prepared by David Cantor, and it was originally my intention to make these notes available to the mathematical public with only quite minor changes. Then, among some old papers of mine, I accidentally came across a long-forgotten manuscript by Chevalley, of pre-war vintage (forgotten, that is to say, both by me and by its author) which, to my taste at least, seemed to have aged very well. It contained a brief but essentially com- plete account of the main features of classfield theory, both local and global; and it soon became obvious that the usefulness of the intended volume would be greatly enhanced if I included such a treatment of this topic. It had to be expanded, in accordance with my own plans, but its outline could be preserved without much change. In fact, I have adhered to it rather closely at some critical points.
内页插图
目录
Chronological table
Prerequisites and notations
Table of notations
PART Ⅰ ELEMENTARY THEORY
Chapter Ⅰ Locally compact fields
1 Finite fields
2 The module in a locally compact field
3 Classification of locally compact fields
4 Structure 0f p-fields
Chapter Ⅱ Lattices and duality over local fields
1 Norms
2 Lattices
3 Multiplicative structure of local fields
4 Lattices over R
5 Duality over local fields
Chapter Ⅲ Places of A-fields
1 A-fields and their completions
2 Tensor-products of commutative fields
3 Traces and norms
4 Tensor-products of A-fields and local fields
Chapter Ⅳ Adeles
1 Adeles of A-fields
2 The main theorems
3 Ideles
4 Ideles of A-fields
Chapter Ⅴ Algebraic number-fields
1, Orders in algebras over Q
2 Lattices over algebraic number-fields
3 Ideals
4 Fundamental sets
Chapter Ⅵ The theorem of Riemann-Roch
Chapter Ⅶ Zeta-functions of A-fields
1 Convergence of Euler products
2 Fourier transforms and standard functions
3 Quasicharacters
4 Quasicharacters of A-fields
5 The functional equation
6 The Dedekind zeta-function
7 L-functions
8 The coefficients of the L-series
Chapter Ⅷ Traces and norms
1 Traces and norms in local fields
2 Calculation of the different
3 Ramification theory
4 Traces and norms in A-fields
5 Splitting places in separable extensions
6 An application to inseparable extensions
PART Ⅱ CLASSFIELD THEORY
Chapter IX Simple algebras
1 Structure of simple algebras
2 The representations of a simple algebra
3 Factor-sets and the Brauer group
4 Cyclic factor-sets
5 Special cyclic factor-sets
Chapter Ⅹ Simple algebras over local fields
1 Orders and lattices
2 Traces and norms
3 Computation of some integrals
Chapter Ⅺ Simple algebras over A-fields
1. Ramification
2. The zeta-function of a simple algebra
3. Norms in simple algebras
4. Simple algebras over algebraic number-fields . .
Chapter Ⅻ. Local classfield theory
1. The formalism of classfield theory
2. The Brauer group of a local field
3. The canonical morphism
4. Ramification of abelian extensions
5. The transfer
Chapter XIII. Global classfield theory
I. The canonical pairing
2. An elementary lemma
3. Hasses "law of reciprocity" .
4. Classfield theory for Q
5. The Hiibert symbol
6. The Brauer group of an A-field
7. The Hilbert p-symbol
8. The kernel of the canonical morphism
9. The main theorems
10. Local behavior of abelian extensions
11. "Classical" classfield theory
12. "Coronidis loco".
Notes to the text
Appendix Ⅰ. The transfer theorem
Appendix Ⅱ. W-groups for local fields
Appendix Ⅲ. Shafarevitchs theorem
Appendix Ⅳ. The Herbrand distribution
Index of definitions
前言/序言
The first part of this volume is based on a course taught at PrincetonUniversity in 1961-62; at that time, an excellent set of notes was preparedby David Cantor, and it was originally my intention to make these notesavailable to the mathematical public with only quite minor changes.Then, among some old papers of mine, I accidentally came across along=forgotten manuscript by Chevalley, of pre-war vintage (forgotten,that is to say, both by me and by its author) which, to my taste at least,seemed to have aged very well. It contained a brief but essentially com-plete account of the main features of classfield theory, both local andglobal; and it soon became obvious that the usefulness of the intendedvolume would be greatly enhanced if I included such a treatment of thistopic. It had to be expanded, in accordance with my own plans, but itsoutline could be preserved without much change. In fact, I have adheredto it rather closely at some critical points.
To improve upon Hecke, in a treatment along classical lines of thetheory of algebrai~ numbers, would be a futile and impossible task. Aswill become apparent from the first pages of this book, I have rathertried to draw the conclusions from the developments of the last thirtyyears, whereby locally compact groups, measure and integration havebeen seen to play an increasingly important role in classical number-theory. In the days of Dirichlet and Hermite, and even of Minkowski,the appeal to "continuous variables" in arithmetical questions may wellhave seemed to come out of some magicians bag of tricks. In retrospect,we see now that the real numbers appear there as one of the infinitelymany completions of the prime field, one which is neither more nor lessinteresting to the arithmetician than its p=adic companions, and thatthere is at least one language and one technique, that of the adeles, for bringing them all together under one roof and making them cooperate for a common purpose. It is needless here to go into the history of thesedevelopments; suffice it to mention such names as Hensel, Hasse, Chevalley, Artin; every one of these, and more recently Iwasawa, Tate, Tamagawa, helped to make some significant step forward along this road. Once the presence of the real field, albeit at infinite distance, ceases to be regarded as a necessary ingredient in the arithmeticians brew.
深入浅出的代数几何之旅:环、域与流形 简介 本书旨在为读者提供一个严谨而富有洞察力的视角,探索代数几何这一迷人领域的核心概念与基本工具。我们聚焦于从最基础的代数结构——环与域的性质出发,逐步构建起理解代数几何的基石,并最终将这些抽象的结构具象化为几何对象——代数簇和概形。本书的撰写遵循“由易到难,循序渐进”的原则,力求在保持数学严谨性的同时,为初学者提供清晰的直觉引导,同时为有一定基础的研究者提供深入的参考价值。 我们深知代数几何的复杂性,因此本书并未试图涵盖该领域的所有前沿课题,而是精选了那些对于构建整体框架至关重要的概念。全书的叙事逻辑围绕“如何用代数语言描述几何形状”这一核心问题展开,通过细致的剖析,揭示出代数与几何之间深刻而优雅的内在联系。 --- 第一部分:代数基础的重塑与深化 在代数几何中,我们所研究的“几何对象”——代数簇,其本质是由多项式方程组定义的零点集。因此,对多项式环及其相关代数结构的深入理解是不可或缺的第一步。 第一章:交换环的结构与模论初步 本章首先回顾并深化了交换环的基本概念,包括理想、商环、素理想与极大理想的定义。我们着重探讨了诺特环(Noetherian Rings)的概念及其重要性。诺特环的局部性质是后续研究的基础,我们详细讨论了如何通过局部化(Localization)操作来提取环在特定素理想处的“局部信息”。例如,我们对 $R$ 在素理想 $P$ 处的局部化 $R_P$ 进行了详尽的分析,并阐释了如何利用这些局部环来研究原环的全局性质。 紧接着,我们引入了模(Modules)的概念,将其视为环上的“向量空间”。模论是研究线性代数的推广,其重要性体现在后续对射(Morphisms)和函子(Functors)的理解上。我们详细分析了平坦模、投射模和内射模的性质,并初步探讨了如何使用这些模的性质来区分不同类型的理想。 第二章:维度的量度:Krull 维度与正则局部环 几何直觉告诉我们,空间的“维度”是一个核心概念。在代数几何中,我们必须用代数语言来精确定义这个概念。本章引入了Krull 维度,将其定义为素理想链的最大长度。我们证明了多项式环 $k[x_1, dots, x_n]$ 的维度恰好是 $n$,从而建立了代数结构与几何维度之间的直观联系。 随后,我们转向对局部性质的精细分析,特别是正则局部环(Regular Local Rings)。正则性是衡量一个点(或局部结构)“良好性”的关键标准。我们引入了正规序列(Regular Sequences)和深度(Depth)的概念,并给出了著名的Cohen-Macaulay 环的刻画。我们深入探讨了Auslander-Buchsbaum 定理,它深刻地揭示了环的正则性与其模的投影维数之间的关系。 --- 第二部分:从代数到几何的桥梁:簇与概形 在建立了坚实的代数基础后,本部分开始将这些抽象结构“视觉化”,引入代数几何的核心研究对象——代数簇和概形。 第三章:代数簇:经典几何的复兴 本章从古典代数几何出发,定义了仿射代数簇(Affine Algebraic Varieties),即 $k^n$ 中多项式零点集 $V(I)$。我们详细阐述了希尔伯特零点定理(Hilbert's Nullstellensatz)的强形式和弱形式,这构成了从理想到簇的映射关系的核心工具。我们证明了理想 $I$ 与其零点集 $V(I)$ 之间存在一种对偶性,特别是对于素理想与不可约簇之间的关系。 接着,我们将研究对象推广到射影空间(Projective Space) $mathbb{P}^n$ 上的射影代数簇。射影空间通过齐次坐标引入,使得处理“无穷远点”成为可能。我们探讨了射影簇的度量、齐次坐标下的理想结构,以及在射影空间中定义的射影零点定理。 第四章:概形理论的建立:“一点”的几何 为了克服经典代数几何中无法处理非零特征域、无法区分某些“奇点”的局限性,我们引入了现代代数几何的基石——概形(Schemes)。概形理论的核心在于局部环化(Sheafification)的过程。 我们首先定义了预层(Presheaf)和层(Sheaf)的概念,这提供了一种在拓扑空间上一致地描述局部数据的方法。然后,我们利用环谱 $ ext{Spec}(R)$ 来构造一个拓扑空间,其中点对应于环 $R$ 的素理想。$ ext{Spec}(R)$ 上的结构层(由局部化构造)定义了概形。 我们详细分析了 $ ext{Spec}(R)$ 上的拓扑性质,特别是Zariski 闭包和谱拓扑的特性。然后,我们定义了结构层 $mathcal{O}_X$,它将环 $R$ 的局部信息赋予了 $ ext{Spec}(R)$ 这个空间。本章的重点在于理解“结构”如何从“代数数据”中自然地涌现出来。 第五章:态射、特征与局部性质的统一 在建立了概形的语言后,我们需要工具来描述不同概形之间的关系。本章定义了态射(Morphisms of Schemes),即保持结构的映射,它们是通过结构层之间的映射(环同态的逆向操作)来定义的。 我们讨论了局部化概形的意义,以及如何利用 $ ext{Spec}(R_P)$ 来研究原概形 $X$ 在点 $P$ 处的局部行为。我们重新审视了正则性:一个概形 $X$ 在点 $x$ 处是正则的,当且仅当其局部环 $mathcal{O}_{X,x}$ 是一个正则局部环。这完美地将第二部分关于正则性的代数结果,无缝地移植到了现代几何的框架中。 最后,本章对特征对几何的影响进行了探讨。我们将对比特征为零的域(如 $mathbb{C}$)和特征为 $p$ 的域(如 $mathbb{F}_p$)上的代数几何,强调了在有限特征下,某些拓扑性质和代数性质会发生微妙但关键的变化。 --- 总结与展望 本书通过从交换代数的基本概念,到局部化、维度理论的构建,最终升华到概形理论的建立,为读者提供了一个完整且逻辑自洽的代数几何入门路径。我们期望读者不仅能掌握这些工具,更能体会到代数结构与几何形态之间那种深刻的、不可分割的统一性。本书为后续深入学习高阶主题,如层上同调、代数曲面的分类、或模空间理论,奠定了坚实的基础。