内容简介
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.
内页插图
目录
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
精彩书摘
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
几何、代数与拓扑的交汇:现代数学核心结构导览 本书将带领读者深入探索现代数学中一个至关重要且相互关联的领域:那些由代数方程定义的、同时又具备丰富几何和拓扑性质的结构。本书聚焦于那些在数论、表示论以及微分几何等多个分支中扮演核心角色的对象——李群及其代数化身。 本书的构建旨在为读者提供一个坚实的基础,从而能够理解这些复杂结构是如何从基础代数概念中涌现出来,并展现出深刻的几何洞察力。我们不会直接深入到群论的抽象定义或具体计算那些高度专业化的李群结构,而是侧重于构建理解这些结构所需的通用框架和必备工具。 第一部分:代数结构的基础构建 本部分着重于铺设理解代数几何和群结构所需的纯代数基础。我们从域论(Field Theory)的稳固根基开始。 域与代数扩张: 详细讨论域的基本性质,特别是伽罗瓦扩张(Galois Extensions)的结构,以及这些扩张如何影响我们后续考察的线性结构。我们探讨了有限域(Finite Fields)的性质及其在有限维代数中的重要性,为后续有限群的理解做准备,尽管本书不直接研究有限群的分类。 环论与交换代数: 引入交换环(Commutative Rings)的概念,重点分析理想(Ideals)和模(Modules)的结构。这包括对诺特定理(Noetherian Property)的深入探讨,理解代数簇(Algebraic Varieties)的定义基础——即如何将多项式方程组转化为环的结构。我们详细阐述了素理想(Prime Ideals)和局部化(Localization)的概念,这些是研究解析对象局部性质的关键工具。 线性代数的高级视角: 重新审视线性代数,但从一个更抽象、更几何化的角度出发。这涉及向量空间(Vector Spaces)上的线性映射,特别是张量积(Tensor Products)的构造及其性质。我们详细分析了半单性理论(Semisimplicity),特别是针对有限维代数上的模,这为理解后续的李代数结构(虽然我们不会深入到李群的上下文)提供了代数背景。 第二部分:几何化:拓扑与微分的桥梁 本部分将代数对象提升到几何和拓扑的层面,关注那些局部具有平滑性质的对象。 拓扑空间与流形基础: 介绍拓扑空间(Topological Spaces)的必要概念,如连通性、紧致性和分离公理。随后,我们过渡到光滑流形(Smooth Manifolds)的严格定义,包括图册(Atlases)、坐标系以及切空间(Tangent Spaces)的概念。切空间的引入至关重要,它将代数计算(向量空间)与几何对象(曲线的斜率、曲面的方向)紧密联系起来。 微分形式与积分: 深入探讨微分形式(Differential Forms)的代数结构,包括楔积(Wedge Product)和外导数(Exterior Derivative)。这部分内容是理解流形上的代数结构如何与度量和积分理论相结合的先决条件。我们详细讨论了德拉姆上同调(De Rham Cohomology)的基本原理,探讨了它如何通过积分来揭示流形的拓扑不变量,即便我们不直接计算特定李群的上同调环。 纤维丛与主丛的初步概念: 为了理解那些结构更复杂的空间,我们需要引入向量丛(Vector Bundles)的概念。我们介绍纤维丛(Fiber Bundles)的一般框架,特别是主丛(Principal Bundles)的结构,理解“局部平凡化”和“过渡函数”的概念。这为后续在更高级课程中研究相关联的代数结构提供了必要的语言基础。 第三部分:矩阵群:线性世界的原型 本部分将前两部分的工具应用于最直观的例子:矩阵群。虽然我们不探讨其作为李群的完整理论,但我们使用它们来展示代数、几何和拓扑的交汇点。 一般线性群的结构: 从一般线性群 GL(n, F) 开始,将其视为一个代数集(Algebraic Set)和李群的第一个例子。我们分析其矩阵乘法和逆元的代数性质。 正交、辛与酉结构: 探讨那些保持特定二次型或双线性形式不变的子群。这包括正交群 O(n) 和辛群 Sp(2n) 的定义。我们关注这些子群是如何通过特定的代数约束(矩阵方程)定义的,以及它们在欧几里得空间中的几何意义(旋转和斜切变换)。 流形结构与李群的局部性质: 在这部分矩阵群的例子中,我们明确展示了它们作为光滑流形的性质。我们分析了这些群的单位元邻域,并阐述了为什么在它们的单位元附近,群的结构可以用一个向量空间(李代数)来线性近似。我们通过对指数映射(Matrix Exponential)的讨论,展示了如何从线性结构(代数)过渡到乘法结构(群),而不深入探讨其逆过程——对李群的完整对数映射分析。 总结: 本书的叙事主线是展示如何利用代数(域、环、模)的严谨性来定义几何对象(流形、向量空间),并最终理解这些对象上变换的群结构。它专注于提供所有必要的“原材料”——从基础的域论到切空间和微分形式——以便读者能够完全掌握现代数学中那些基于线性结构的复杂理论,尤其是那些依赖于矩阵化模型的代数几何和拓扑现象。本书旨在培养一种跨越代数与几何边界的直觉,是深入研究更高级拓扑群论或代数几何的理想垫脚石。