內容簡介
For this printing, I have corrected some errors and made numerous minor changes in the interest of clarity. The most significant corrections occur in Sections 4.2, 4.3, 5.5, 30.3, 32.1, and 32.3. I have also updated the biblio-graphy to some extent. Thanks are due to a number of readers who took the trouble to point out errors, or obscurities; especially helpful were the detailed comments of Jose Antonio Vargas.
內頁插圖
目錄
I.AlgebraicGeometry
0.SomeCommutativeAlgebra
1.AffineandProjectiveVarieties
1.1 IdealsandAflineVarieties
1.2 ZariskiTopologyonAffineSpace
1.3 IrreducibleComponents
1.4 ProductsofAffineVarieties
1.5 AffineAlgebrasandMorphisms
1.6 ProjectiveVarieties
1.7 ProductsofProjectiveVarieties
1.8 FlagVarieties
2.Varieties
2.1 LocalRings
2.2 Prevarieties
2.3 Morphisms
2.4 Products
2.5 HausdorffAxiom
3.Dimension
3.1 DimensionofaVariety
3.2 DimensionofaSubvariety
3.3 DimensionTheorem
3.4 Consequences
4.Morphisms
4.1 FibresofaMorphism
4.2 FiniteMorphisms
4.3 ImageofaMorphism
4.4 ConstructibleSets
4.5 OpenMorphisms
4.6 BijectiveMorphisms
4.7 BirationalMorphisms
5.TangentSpaces
5.1 ZariskiTangentSpace
5.2 ExistenceofSimplePoints
5.3 LocalRingofaSimplePoint
5.4 DifferentialofaMorphism
5.5 DifferentialCriterionforSeparability
6.CompleteVarieties
6.1 BasicProperties
6.2 CompletenessofProjectiveVarieties
6.3 VarietiesIsomorphictoP
6.4 AutomorphismsofP
II.AflineAlgebraicGroups
7.BasicConceptsandExamples
7.1 TheNotionofAlgebraicGroup
7.2 SomeClassicalGroups
7.3 IdentityComponent
7.4 SubgroupsandHomomorphisms
7.5 GenerationbyIrreducibleSubsets
7.6 HopfAIgebras
8.ActionsofAlgebraicGroupsonVarieties
8.1 GroupActions
8.2 ActionsofAlgebraicGroups
8.3 ClosedOrbits
8.4 SemidirectProducts
8.5 TranslationofFunctions
8.6 LinearizationofAffineGroups
III.LieAlgebras
9.LieAlgebraofanAlgebraicGroup
9.1 LieAlgebrasandTangentSpaces
9.2 Convolution
9.3 Examples
9.4 SubgroupsandLieSubalgebras
9.5 DualNumbers
10.Differentiation
10.1 SomeElementaryFormulas
10.2 DifferentialofRightTranslation
10.3 TheAdjointRepresentation
10.4 DifferentialofAd
10.5 Commutators
10.6 Centralizers
10.7 AutomorphismsandDerivations
IV.HomogeneousSpaces
11.ConstructionofCertainRepresentations
11.1 ActiononExteriorPowers
11.2 ATheoremofChevalley
11.3 PassagetoProjectiveSpace
11.4 CharactersandSemi-lnvariants
11.5 NormalSubgroups
12.Quotients
12.1 UniversalMappingProperty
12.2 TopologyofY
12.3 FunctionsonY
12.4 Complements
12.5 Characteristic0
V.Characteristic0Theory
13.CorrespondenceBetweenGroupsandLieAlgebras
13.1 TheLatticeCorrespondence
13.2 InvariantsandInvariantSubspaces
13.3 NormalSubgroupsandIdeals
13.4 CentersandCentralizers
13.5 SemisimpleGroupsandLieAlgebras
14.SemisimpleGroups
14.1 TheAdjointRepresentation
14.2 SubgroupsoraSemisimpleGroup
14.3 CompleteReducibilityofRepresentations
VI.SemisimpleandUnipotentElements
15.Jordan-ChevalleyDecomposition
15.1 DecompositionofaSingleEndomorphism
15.2 GL(n,K)andgl(n,K)
15.3 JordanDecompositioninAlgebraicGroups
15.4 CommutingSetsofEndomorphisms
15.5 StructureofCommutativeAlgebraicGroups
16.DiagonalizableGroups
16.1 Charactersandd-Groups
16.2 Tori
16.3 RigidityofDiagonalizableGroups
16.4 WeightsandRoots
VII.SolvableGroups
17.NilpotentandSolvableGroups
17.1 AGroup-TheoreticLemma
17.2 CommutatorGroups
17.3 SolvableGroups
17.4 NilpotentGroups
17.5 UnipotentGroups
17.6 Lie-KolchinTheorem
18.SemisimpleElements
18.1 GlobalandInfinitesimalCentralizers
18.2 ClosedConjugacyClasses
18.3 ActionofaSemisimpleElementonaUnipotentGroup
18.4 ActionofaDiagonalizableGroup
19.ConnectedSolvableGroups
19.1 AnExactSequence
19.2 TheNilpotentCase
19.3 TheGeneralCase
19.4 NormalizerandCentralizer
19.5 SolvableandUnipotentRadicals
20.OneDimensionalGroups
20.1 CommutativityofG
20.2 VectorGroupsande-Groups
20.3 Propertiesofp-Polynomials
20.4 AutomorphismsofVectorGroups
20.5 TheMainTheorem
VIII.BorelSubgroups
21.FixedPointandConjugacyTheorems
21.1 ReviewofCompleteVarieties
21.2 FixedPointTheorem
21.3 ConjugacyofBorelSubgroupsandMaximalTori
21.4 FurtherConsequences
22.DensityandConnectednessTheorems
22.1 TheMainLemma
22.2 DensityTheorem
22.3 ConnectednessTheorem
22.4 BorelSubgroupsofCG(S)
22.5 CartanSubgroups:Summary
23.NormalizerTheorem
23.1 StatementoftheTheorem
23.2 ProofoftheTheorem
23.3 TheVarietyG/B
23.4 Summary
IX.CentralizersofTori
24.RegularandSingularTori
24.1 WeylGroups
24.2 RegularTori
24.3 SingularToriandRoots
24.4 Regular1-ParameterSubgroups
25.ActionofaMaximalTorusonG/B
25.1 Actionofa1-ParameterSubgroup
25.2 ExistenceofEnoughFixedPoints
25.3 GroupsofSemisimpleRank1
25.4 WeylChambers
26.TheUnipotentRadical
26.1 CharacterizationofRu(G)
26.2 SomeConsequences
26.3 TheGroupsUa
X.StructureofReductiveGroups
27.TheRootSystem
27.1 AbstractRootSystems
27.2 TheIntegralityAxiom
27.3 SimpleRoots
27.4 TheAutomorphismGroupofaSemisimpleGroup
27.5 SimpleComponents
28.BruhatDecomposition
28.1 T-StableSubgroupsofBu
28.2 GroupsofSemisimpleRank1
28.3 TheBruhatDecomposition
28.4 NormalForminG
28.5 Complements
29.TitsSystems
29.1 Axioms
29.2 BruhatDecomposition
29.3 ParabolicSubgroups
29.4 GeneratorsandRelationsforW
29.5 NormalSubgroupsofG
30.ParabolicSubgroups
30.1 StandardParabolicSubgroups
30.2 LeviDecompositions
30.3 ParabolicSubgroupsAssociatedtoCertainUnipotentGroups
30.4 MaximalSubgroupsandMaximalUnipotentSubgroups
XI.RepresentationsandClassificationofSemisimpleGroups
31.Representations
31.1 Weights
31.2 MaximalVectors
31.3 IrreducibleRepresentations
31.4 ConstructionofIrreducibleRepresentations
31.5 MultiplicitiesandMinimalHighestWeights
31.6 ContragredientsandInvariantBilinearForms
32.IsomorphismTheorem
32.1 TheClassificationProblem
32.2 ExtensionofψTtoN(T)
32.3 ExtensionofψTtoZa
32.4 ExtensionofψTtoTUa
32.5 ExtensionofψTtoB
32.6 Multiplicativityofψ
33.RootSystemsofRank2
33.1 Reformulationof(A),(B),(C)
33.2 SomePreliminaries
33.3 TypeA2
33.4 TypeB2
33.5 TypeG2
33.6 TheExistenceProblem
XII.SurveyofRationalityProperties
34.FieldsofDefinition
34.1 Foundations
34.2 ReviewofEarlierChapters
34.3 Tori
34.4 SomeBasicTheorems
34.5 Borei-TitsStructureTheory
34.6 AnExample:OrthogonalGroups
35.SpecialCases
35.1 SplitandQuasisplitGroups
35.2 FiniteFields
35.3 TheRealField
35.4 LocalFields
35.5 Classification
Appendix.RootSystems
Bibliography
IndexofTerminology
IndexofSymbols
精彩書摘
Over the last two decades the Borel-Chevalley theory of Iinear algebraic groups(as further developed by Borel,Steinberg,Tits,and others)has made possible significant progress In a aurabef of areas:scmisimple Lie groups and arithmetic subgroups,p-adic groups,classical linear groups,finite simple groups,invariant theory。etc.Unfortunately,the subject has not been as accessible as it ought to be.in part due to the fairly substantial background in algebraic geometry assumed by Chevalley ,Borei , Borel,Tits .The difliculty of the theory also stems in Dart from the fact that the main results culminate a Iong series of arguments which are hard to“see through”from beginning to end.In writing this introductory text. aimed at the second year graduate level.I have tried to take these factors into account.
First.the requisite algebraic geometry has been treated in fullin Chapter I.modulo some more.or-less standard results from commutative algebra (quoted in§o),e.g.,the theorem that a regular local ring is an integrally closed domain.The treatment is intentionally somewhat crude and is not at all scheme-oriented.In fact.everything is done over an algebraically closed field K(of arbitrary characteristic).even though most of the eventual applications involve a feld of definition k.I believe this c.an be iustified as follows.In order to work over k from the outset,it would be necessary to spend a good deal of time perfecting the foundations.and then the only rationality statements proved along the way would be Of a minor sort rcf (34.2)).The deeper rationality properties can only be appreciated after the reader has reached Chapter X.(A survey of such results,without proofs, is given in Chapter XlI.)
Second.a special effort has been made to render the exposition trans. parent.Except for a digression into characteristic 0 in Chapter V.the development from Chapter II to Chapter XI is fairly“linear”.covering the foundations,the structure of connected solvable groups,and then the structure,representations and classification of reductive groups.The Iecture notes of BoreI 41,which constitute an improvement of the methods in Chevalley,are the basic source for Chapters II-IV,Vl-X,while Chapter xI is a hybrid of Chevalley and SGAD.From27 on the basic facts about root systems arc used constantly:these are listed(with suitable ref- erences)in the Appendix.Apart from{io,the Appendix,and a reference to a theorem of Burnside in(1 7.5),the text iS self-contained.But the reader is asked to verifv some minor ooints as exercises.
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前言/序言
幾何、代數與拓撲的交匯:現代數學核心結構導覽 本書將帶領讀者深入探索現代數學中一個至關重要且相互關聯的領域:那些由代數方程定義的、同時又具備豐富幾何和拓撲性質的結構。本書聚焦於那些在數論、錶示論以及微分幾何等多個分支中扮演核心角色的對象——李群及其代數化身。 本書的構建旨在為讀者提供一個堅實的基礎,從而能夠理解這些復雜結構是如何從基礎代數概念中湧現齣來,並展現齣深刻的幾何洞察力。我們不會直接深入到群論的抽象定義或具體計算那些高度專業化的李群結構,而是側重於構建理解這些結構所需的通用框架和必備工具。 第一部分:代數結構的基礎構建 本部分著重於鋪設理解代數幾何和群結構所需的純代數基礎。我們從域論(Field Theory)的穩固根基開始。 域與代數擴張: 詳細討論域的基本性質,特彆是伽羅瓦擴張(Galois Extensions)的結構,以及這些擴張如何影響我們後續考察的綫性結構。我們探討瞭有限域(Finite Fields)的性質及其在有限維代數中的重要性,為後續有限群的理解做準備,盡管本書不直接研究有限群的分類。 環論與交換代數: 引入交換環(Commutative Rings)的概念,重點分析理想(Ideals)和模(Modules)的結構。這包括對諾特定理(Noetherian Property)的深入探討,理解代數簇(Algebraic Varieties)的定義基礎——即如何將多項式方程組轉化為環的結構。我們詳細闡述瞭素理想(Prime Ideals)和局部化(Localization)的概念,這些是研究解析對象局部性質的關鍵工具。 綫性代數的高級視角: 重新審視綫性代數,但從一個更抽象、更幾何化的角度齣發。這涉及嚮量空間(Vector Spaces)上的綫性映射,特彆是張量積(Tensor Products)的構造及其性質。我們詳細分析瞭半單性理論(Semisimplicity),特彆是針對有限維代數上的模,這為理解後續的李代數結構(雖然我們不會深入到李群的上下文)提供瞭代數背景。 第二部分:幾何化:拓撲與微分的橋梁 本部分將代數對象提升到幾何和拓撲的層麵,關注那些局部具有平滑性質的對象。 拓撲空間與流形基礎: 介紹拓撲空間(Topological Spaces)的必要概念,如連通性、緊緻性和分離公理。隨後,我們過渡到光滑流形(Smooth Manifolds)的嚴格定義,包括圖冊(Atlases)、坐標係以及切空間(Tangent Spaces)的概念。切空間的引入至關重要,它將代數計算(嚮量空間)與幾何對象(麯綫的斜率、麯麵的方嚮)緊密聯係起來。 微分形式與積分: 深入探討微分形式(Differential Forms)的代數結構,包括楔積(Wedge Product)和外導數(Exterior Derivative)。這部分內容是理解流形上的代數結構如何與度量和積分理論相結閤的先決條件。我們詳細討論瞭德拉姆上同調(De Rham Cohomology)的基本原理,探討瞭它如何通過積分來揭示流形的拓撲不變量,即便我們不直接計算特定李群的上同調環。 縴維叢與主叢的初步概念: 為瞭理解那些結構更復雜的空間,我們需要引入嚮量叢(Vector Bundles)的概念。我們介紹縴維叢(Fiber Bundles)的一般框架,特彆是主叢(Principal Bundles)的結構,理解“局部平凡化”和“過渡函數”的概念。這為後續在更高級課程中研究相關聯的代數結構提供瞭必要的語言基礎。 第三部分:矩陣群:綫性世界的原型 本部分將前兩部分的工具應用於最直觀的例子:矩陣群。雖然我們不探討其作為李群的完整理論,但我們使用它們來展示代數、幾何和拓撲的交匯點。 一般綫性群的結構: 從一般綫性群 GL(n, F) 開始,將其視為一個代數集(Algebraic Set)和李群的第一個例子。我們分析其矩陣乘法和逆元的代數性質。 正交、辛與酉結構: 探討那些保持特定二次型或雙綫性形式不變的子群。這包括正交群 O(n) 和辛群 Sp(2n) 的定義。我們關注這些子群是如何通過特定的代數約束(矩陣方程)定義的,以及它們在歐幾裏得空間中的幾何意義(鏇轉和斜切變換)。 流形結構與李群的局部性質: 在這部分矩陣群的例子中,我們明確展示瞭它們作為光滑流形的性質。我們分析瞭這些群的單位元鄰域,並闡述瞭為什麼在它們的單位元附近,群的結構可以用一個嚮量空間(李代數)來綫性近似。我們通過對指數映射(Matrix Exponential)的討論,展示瞭如何從綫性結構(代數)過渡到乘法結構(群),而不深入探討其逆過程——對李群的完整對數映射分析。 總結: 本書的敘事主綫是展示如何利用代數(域、環、模)的嚴謹性來定義幾何對象(流形、嚮量空間),並最終理解這些對象上變換的群結構。它專注於提供所有必要的“原材料”——從基礎的域論到切空間和微分形式——以便讀者能夠完全掌握現代數學中那些基於綫性結構的復雜理論,尤其是那些依賴於矩陣化模型的代數幾何和拓撲現象。本書旨在培養一種跨越代數與幾何邊界的直覺,是深入研究更高級拓撲群論或代數幾何的理想墊腳石。