內容簡介
《變分法(第4版)》是《變分法》第四版,主要講述在非綫性偏微分方程和哈密頓係統中的應用,繼第一版齣版十八年再次全新呈現。整《變分法(第4版)》都做瞭大量的修改,僅500多條參考書目就將其價值大大提升。第四版中主要講述變分微積分,增加瞭該領域的新進展。這也是一部變分法學習的教程,特彆講述瞭yamabe流的收斂和脹開現象以及新研究發現的調和映射和麯麵中熱流的嚮後小泡形成。
內頁插圖
目錄
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
精彩書摘
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
深入理解拓撲、變分與動力係統的交匯:現代數學物理的關鍵視角 本書旨在為讀者提供一個係統而深入的框架,用以探索現代數學物理中至關重要的三大支柱:拓撲學、泛函分析中的變分法,以及非綫性動力係統。它並非一本傳統的、專注於特定方程求解技巧的教科書,而是一部側重於概念統一性、理論深度和跨學科應用的專著。全書的敘事綫索圍繞著如何利用幾何和拓撲的直覺,來處理高度非綫性的分析問題,尤其關注那些在物理學和幾何學中扮演核心角色的係統。 本書的第一部分著重於幾何化和拓撲基礎。我們首先迴顧必要的微分幾何工具,包括流形上的張量分析、外微分與德拉姆上同調的初級概念。然而,重點迅速轉嚮拓撲不變量在分析問題中的作用。我們將深入探討Morse理論的現代闡釋,不再僅僅將其視為計算拓撲的工具,而是將其視為理解函數空間(泛函)臨界點性質的強大框架。尤其關注山路引理(Mountain Pass Lemma)的推廣及其在證明關鍵存在性定理中的應用。這裏的討論強調的是拓撲結構如何直接限製瞭可能的解集,例如,在探討具有某些對稱性或邊界條件的非綫性橢圓型方程解的存在性時,拓撲餘維度的概念如何幫助我們規避局部極小值的陷阱。 第二部分是本書的核心——泛函分析與廣義變分原理。我們在此部分嚴格審視變分法的理論基礎,但重點在於如何將這些理論擴展到無限維空間。標準的是,我們討論索伯列夫空間、Hadamard可微性以及圍繞緊緻性的睏難。關鍵的章節深入探討磨損空間(Metric Spaces)上的變分概念,特彆是粗糙化(Coarsening)和定點理論(Fixed Point Theory)的變分視角。書中對次梯度(Subgradient)的討論非常詳盡,它為處理非光滑能量泛函——這在隨機力學和材料科學中極為常見——提供瞭必要的分析工具。我們構建瞭從古典歐拉-拉格朗日方程到非綫性偏微分方程的嚴格推導過程,強調守恒律與變分原理之間的深刻對偶關係。 一個重要的論述焦點是極小麯麵理論的現代視角。我們利用Möbius變換和共形映射理論,展示如何將二維歐幾裏得空間中的極小麯麵問題轉化為更高維空間中的規範理論(Gauge Theory)問題。此處,我們引入瞭Catenoid 和 Helicoid的全局結構分析,並闡述瞭這些結構的共形嵌入性質如何與某些非綫性橢圓方程的解的奇點形成聯係。 第三部分將理論分析應用於非綫性動力係統。這裏,我們關注拉格朗日力學和哈密頓力學在分析復雜係統中的適用性。與側重於數值積分的書籍不同,我們的重點在於相空間幾何。我們詳細分析瞭龐加萊截麵的構造及其在區分周期軌道和準周期軌道上的作用。書中對KAM理論(Kolmogorov-Arnold-Moser Theory)的討論采取瞭一種更具幾何感的解釋,強調在微擾下不變積分麯麵的存在性如何對應於係統的穩定性。我們探討瞭如何利用辛幾何(Symplectic Geometry)的語言來重新錶述哈密頓係統,從而揭示隱藏的拓撲約束,例如,拉格朗日係統在緊緻流形上周期解的Morse指數的性質。 此外,本書特彆闢齣章節探討非綫性橢圓型方程在黎曼幾何中的應用,例如Yamabe方程和Ricci流的早期分析。我們展示瞭如何通過引入適當的能量泛函(如Dirichlet能量或麵積泛函),利用變分方法來證明解的存在性、唯一性,乃至其漸近行為。重點在於理解邊界作用(Boundary Effects)和漸近展開(Asymptotic Expansions)在描述解的局部正則性方麵的關鍵作用。 本書的價值在於其深度整閤瞭來自不同領域的精確技術和深刻直覺。它要求讀者對分析有堅實的背景,並渴望超越標準的計算技巧,去把握支配這些復雜係統的拓撲結構和內在對稱性。最終目標是培養讀者一種能力:能夠從一個物理或幾何問題中,提煉齣一個具有深刻拓撲內涵的泛函,並利用現代分析工具來揭示其臨界點的幾何意義。全書結構嚴謹,推導詳盡,旨在成為數學物理、幾何分析和理論力學領域研究人員和高年級研究生的重要參考資料。