内容简介
《变分法(第4版)》是《变分法》第四版,主要讲述在非线性偏微分方程和哈密顿系统中的应用,继第一版出版十八年再次全新呈现。整《变分法(第4版)》都做了大量的修改,仅500多条参考书目就将其价值大大提升。第四版中主要讲述变分微积分,增加了该领域的新进展。这也是一部变分法学习的教程,特别讲述了yamabe流的收敛和胀开现象以及新研究发现的调和映射和曲面中热流的向后小泡形成。
内页插图
目录
Chapter I.the direct methods in the calculus of variations
1.lower semi-continuity
degenerate elliptic equations
-minimal partitioning hypersurfaces
-minimal hypersurfaces in riemannian manifolds
-a general lower semi-continuity result
2.constraints
semilinear elliptic boundary value problems
-perron's method in a variational guise
-the classical plateau problem
3.compensated compactness
applications in elasticity
-convergence results for nonlinear elliptic equations
-hardy space methods
4.the concentration-compactness principle
existence of extremal functions for sobolev embeddings
5.ekeland's variational principle
existence of minimizers for quasi-convex functionals
6.duality
hamiltonian systems
-periodic solutions of nonlinear wave equations
7.minimization problems depending on parameters
harmonic maps with singularities
Chapter Ⅱ.minimax methods
1.the finite dimensional case
2.the palais-smale condition
3.a general deformation lemma
pseudo-gradient flows on banach spaces
-pseudo-gradient flows on manifolds
4.the minimax principle
closed geodesics on spheres
5.index theory
krasnoselskii genus
-minimax principles for even functional
-applications to semilinear elliptic problems
-general index theories
-ljusternik-schnirelman category
-a geometrical si-index
-multiple periodic orbits of hamiltonian systems
6.the mountain pass lemma and its variants
applications to semilinear elliptic boundary value problems
-the symmetric mountain pass lemma
-application to semilinear equa- tions with symmetry
7.perturbation theory
applications to semilinear elliptic equations
8.linking
applications to semilinear elliptic equations
-applications to hamil- tonian systems
9.parameter dependence
10.critical points of mountain pass type
multiple solutions of coercive elliptic problems
11.non-differentiable fhnctionals
12.ljnsternik-schnirelman theory on convex sets
applications to semilinear elliptic boundary value problems
Chapter Ⅲ.Limit cases of the palais-smale condition
1.pohozaev's non-existence result
2.the brezis-nirenberg result
constrained minimization
-the unconstrained case: local compact- ness
-multiple solutions
3.the effect of topology
a global compactness result, 184 -positive solutions on annular-shaped regions, 190
4.the yamabe problem
the variational approach
-the locally conformally flat case
-the yamabe flow
-the proof of theorem4.9 (following ye [1])
-convergence of the yamabe flow in the general case
-the compact case ucc
-bubbling: the casu
5.the dirichlet problem for the equation of constant mean curvature
small solutions
-the volume functional
- wente's uniqueness result
-local compactness
-large solutions
6.harmonic maps of riemannian surfaces
the euler-lagrange equations for harmonic maps
-bochner identity
-the homotopy problem and its functional analytic setting
-existence and non-existence results
-the heat flow for harmonic maps
-the global existence result
-the proof of theorem 6.6
-finite-time blow-up
-reverse bubbling and nonuniqueness
appendix a
sobolev spaces
-hslder spaces
-imbedding theorems
-density theorem
-trace and extension theorems
-poincar4 inequality
appendix b
schauder estimates
-lp-theory
-weak solutions
-areg-ularityresult
-maximum principle
-weak maximum principle
-application
appendix c
frechet differentiability
-natural growth conditions
references
index
精彩书摘
Almost twenty years after conception of the first edition, it was a challenge to prepare an updated version of this text on the Calculus of Variations. The field has truely advanced dramatically since that time, to an extent that I find it impossible to give a comprehensive account of all the many important developments that have occurred since the last edition appeared. Fortunately, an excellent overview of the most significant results, with a focus on functional analytic and Morse theoretical aspects of the Calculus of Variations, can be found in the recent survey paper by Ekeland-Ghoussoub [1]. I therefore haveonly added new material directly related to the themes originally covered.
Even with this restriction, a selection had to be made. In view of the fact that flow methods are emerging as the natural tool for studying variational problems in the field of Geometric Analysis, an emphasis was placed on advances in this domain. In particular, the present edition includes the proof for the convergence of the Yamabe flow on an arbitrary closed manifold of dimension 3 m 5 for initial data allowing at most single-point blow-up.Moreover, we give a detailed treatment of the phenomenon of blow-up and discuss the newly discovered results for backward bubbling in the heat flow for harmonic maps of surfaces.
Aside from these more significant additions, a number of smaller changes have been made throughout the text, thereby taking care not to spoil the freshness of the original presentation. References have been updated, whenever possible, and several mistakes that had survived the past revisions have now been eliminated. I would like to thank Silvia Cingolani, Irene Fouseca, Emmanuel Hebey, and Maximilian Schultz for helpful comments in this regard. Moreover,I am indebted to Gilles Angelsberg, Ruben Jakob, Reto Miiller, and Melanie Rupfiin, for carefully proof-reading the new material.
……
前言/序言
深入理解拓扑、变分与动力系统的交汇:现代数学物理的关键视角 本书旨在为读者提供一个系统而深入的框架,用以探索现代数学物理中至关重要的三大支柱:拓扑学、泛函分析中的变分法,以及非线性动力系统。它并非一本传统的、专注于特定方程求解技巧的教科书,而是一部侧重于概念统一性、理论深度和跨学科应用的专著。全书的叙事线索围绕着如何利用几何和拓扑的直觉,来处理高度非线性的分析问题,尤其关注那些在物理学和几何学中扮演核心角色的系统。 本书的第一部分着重于几何化和拓扑基础。我们首先回顾必要的微分几何工具,包括流形上的张量分析、外微分与德拉姆上同调的初级概念。然而,重点迅速转向拓扑不变量在分析问题中的作用。我们将深入探讨Morse理论的现代阐释,不再仅仅将其视为计算拓扑的工具,而是将其视为理解函数空间(泛函)临界点性质的强大框架。尤其关注山路引理(Mountain Pass Lemma)的推广及其在证明关键存在性定理中的应用。这里的讨论强调的是拓扑结构如何直接限制了可能的解集,例如,在探讨具有某些对称性或边界条件的非线性椭圆型方程解的存在性时,拓扑余维度的概念如何帮助我们规避局部极小值的陷阱。 第二部分是本书的核心——泛函分析与广义变分原理。我们在此部分严格审视变分法的理论基础,但重点在于如何将这些理论扩展到无限维空间。标准的是,我们讨论索伯列夫空间、Hadamard可微性以及围绕紧致性的困难。关键的章节深入探讨磨损空间(Metric Spaces)上的变分概念,特别是粗糙化(Coarsening)和定点理论(Fixed Point Theory)的变分视角。书中对次梯度(Subgradient)的讨论非常详尽,它为处理非光滑能量泛函——这在随机力学和材料科学中极为常见——提供了必要的分析工具。我们构建了从古典欧拉-拉格朗日方程到非线性偏微分方程的严格推导过程,强调守恒律与变分原理之间的深刻对偶关系。 一个重要的论述焦点是极小曲面理论的现代视角。我们利用Möbius变换和共形映射理论,展示如何将二维欧几里得空间中的极小曲面问题转化为更高维空间中的规范理论(Gauge Theory)问题。此处,我们引入了Catenoid 和 Helicoid的全局结构分析,并阐述了这些结构的共形嵌入性质如何与某些非线性椭圆方程的解的奇点形成联系。 第三部分将理论分析应用于非线性动力系统。这里,我们关注拉格朗日力学和哈密顿力学在分析复杂系统中的适用性。与侧重于数值积分的书籍不同,我们的重点在于相空间几何。我们详细分析了庞加莱截面的构造及其在区分周期轨道和准周期轨道上的作用。书中对KAM理论(Kolmogorov-Arnold-Moser Theory)的讨论采取了一种更具几何感的解释,强调在微扰下不变积分曲面的存在性如何对应于系统的稳定性。我们探讨了如何利用辛几何(Symplectic Geometry)的语言来重新表述哈密顿系统,从而揭示隐藏的拓扑约束,例如,拉格朗日系统在紧致流形上周期解的Morse指数的性质。 此外,本书特别辟出章节探讨非线性椭圆型方程在黎曼几何中的应用,例如Yamabe方程和Ricci流的早期分析。我们展示了如何通过引入适当的能量泛函(如Dirichlet能量或面积泛函),利用变分方法来证明解的存在性、唯一性,乃至其渐近行为。重点在于理解边界作用(Boundary Effects)和渐近展开(Asymptotic Expansions)在描述解的局部正则性方面的关键作用。 本书的价值在于其深度整合了来自不同领域的精确技术和深刻直觉。它要求读者对分析有坚实的背景,并渴望超越标准的计算技巧,去把握支配这些复杂系统的拓扑结构和内在对称性。最终目标是培养读者一种能力:能够从一个物理或几何问题中,提炼出一个具有深刻拓扑内涵的泛函,并利用现代分析工具来揭示其临界点的几何意义。全书结构严谨,推导详尽,旨在成为数学物理、几何分析和理论力学领域研究人员和高年级研究生的重要参考资料。