內容簡介
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.
內頁插圖
目錄
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.
深入淺齣的代數幾何之旅:環、域與流形 簡介 本書旨在為讀者提供一個嚴謹而富有洞察力的視角,探索代數幾何這一迷人領域的核心概念與基本工具。我們聚焦於從最基礎的代數結構——環與域的性質齣發,逐步構建起理解代數幾何的基石,並最終將這些抽象的結構具象化為幾何對象——代數簇和概形。本書的撰寫遵循“由易到難,循序漸進”的原則,力求在保持數學嚴謹性的同時,為初學者提供清晰的直覺引導,同時為有一定基礎的研究者提供深入的參考價值。 我們深知代數幾何的復雜性,因此本書並未試圖涵蓋該領域的所有前沿課題,而是精選瞭那些對於構建整體框架至關重要的概念。全書的敘事邏輯圍繞“如何用代數語言描述幾何形狀”這一核心問題展開,通過細緻的剖析,揭示齣代數與幾何之間深刻而優雅的內在聯係。 --- 第一部分:代數基礎的重塑與深化 在代數幾何中,我們所研究的“幾何對象”——代數簇,其本質是由多項式方程組定義的零點集。因此,對多項式環及其相關代數結構的深入理解是不可或缺的第一步。 第一章:交換環的結構與模論初步 本章首先迴顧並深化瞭交換環的基本概念,包括理想、商環、素理想與極大理想的定義。我們著重探討瞭諾特環(Noetherian Rings)的概念及其重要性。諾特環的局部性質是後續研究的基礎,我們詳細討論瞭如何通過局部化(Localization)操作來提取環在特定素理想處的“局部信息”。例如,我們對 $R$ 在素理想 $P$ 處的局部化 $R_P$ 進行瞭詳盡的分析,並闡釋瞭如何利用這些局部環來研究原環的全局性質。 緊接著,我們引入瞭模(Modules)的概念,將其視為環上的“嚮量空間”。模論是研究綫性代數的推廣,其重要性體現在後續對射(Morphisms)和函子(Functors)的理解上。我們詳細分析瞭平坦模、投射模和內射模的性質,並初步探討瞭如何使用這些模的性質來區分不同類型的理想。 第二章:維度的量度:Krull 維度與正則局部環 幾何直覺告訴我們,空間的“維度”是一個核心概念。在代數幾何中,我們必須用代數語言來精確定義這個概念。本章引入瞭Krull 維度,將其定義為素理想鏈的最大長度。我們證明瞭多項式環 $k[x_1, dots, x_n]$ 的維度恰好是 $n$,從而建立瞭代數結構與幾何維度之間的直觀聯係。 隨後,我們轉嚮對局部性質的精細分析,特彆是正則局部環(Regular Local Rings)。正則性是衡量一個點(或局部結構)“良好性”的關鍵標準。我們引入瞭正規序列(Regular Sequences)和深度(Depth)的概念,並給齣瞭著名的Cohen-Macaulay 環的刻畫。我們深入探討瞭Auslander-Buchsbaum 定理,它深刻地揭示瞭環的正則性與其模的投影維數之間的關係。 --- 第二部分:從代數到幾何的橋梁:簇與概形 在建立瞭堅實的代數基礎後,本部分開始將這些抽象結構“視覺化”,引入代數幾何的核心研究對象——代數簇和概形。 第三章:代數簇:經典幾何的復興 本章從古典代數幾何齣發,定義瞭仿射代數簇(Affine Algebraic Varieties),即 $k^n$ 中多項式零點集 $V(I)$。我們詳細闡述瞭希爾伯特零點定理(Hilbert's Nullstellensatz)的強形式和弱形式,這構成瞭從理想到簇的映射關係的核心工具。我們證明瞭理想 $I$ 與其零點集 $V(I)$ 之間存在一種對偶性,特彆是對於素理想與不可約簇之間的關係。 接著,我們將研究對象推廣到射影空間(Projective Space) $mathbb{P}^n$ 上的射影代數簇。射影空間通過齊次坐標引入,使得處理“無窮遠點”成為可能。我們探討瞭射影簇的度量、齊次坐標下的理想結構,以及在射影空間中定義的射影零點定理。 第四章:概形理論的建立:“一點”的幾何 為瞭剋服經典代數幾何中無法處理非零特徵域、無法區分某些“奇點”的局限性,我們引入瞭現代代數幾何的基石——概形(Schemes)。概形理論的核心在於局部環化(Sheafification)的過程。 我們首先定義瞭預層(Presheaf)和層(Sheaf)的概念,這提供瞭一種在拓撲空間上一緻地描述局部數據的方法。然後,我們利用環譜 $ ext{Spec}(R)$ 來構造一個拓撲空間,其中點對應於環 $R$ 的素理想。$ ext{Spec}(R)$ 上的結構層(由局部化構造)定義瞭概形。 我們詳細分析瞭 $ ext{Spec}(R)$ 上的拓撲性質,特彆是Zariski 閉包和譜拓撲的特性。然後,我們定義瞭結構層 $mathcal{O}_X$,它將環 $R$ 的局部信息賦予瞭 $ ext{Spec}(R)$ 這個空間。本章的重點在於理解“結構”如何從“代數數據”中自然地湧現齣來。 第五章:態射、特徵與局部性質的統一 在建立瞭概形的語言後,我們需要工具來描述不同概形之間的關係。本章定義瞭態射(Morphisms of Schemes),即保持結構的映射,它們是通過結構層之間的映射(環同態的逆嚮操作)來定義的。 我們討論瞭局部化概形的意義,以及如何利用 $ ext{Spec}(R_P)$ 來研究原概形 $X$ 在點 $P$ 處的局部行為。我們重新審視瞭正則性:一個概形 $X$ 在點 $x$ 處是正則的,當且僅當其局部環 $mathcal{O}_{X,x}$ 是一個正則局部環。這完美地將第二部分關於正則性的代數結果,無縫地移植到瞭現代幾何的框架中。 最後,本章對特徵對幾何的影響進行瞭探討。我們將對比特徵為零的域(如 $mathbb{C}$)和特徵為 $p$ 的域(如 $mathbb{F}_p$)上的代數幾何,強調瞭在有限特徵下,某些拓撲性質和代數性質會發生微妙但關鍵的變化。 --- 總結與展望 本書通過從交換代數的基本概念,到局部化、維度理論的構建,最終升華到概形理論的建立,為讀者提供瞭一個完整且邏輯自洽的代數幾何入門路徑。我們期望讀者不僅能掌握這些工具,更能體會到代數結構與幾何形態之間那種深刻的、不可分割的統一性。本書為後續深入學習高階主題,如層上同調、代數麯麵的分類、或模空間理論,奠定瞭堅實的基礎。