內容簡介
2007年,陶哲軒創立瞭一個內容豐富的數學博客,內容從他自己的研究工作和其他新近的數學進展,到他的授課講義,包括各種非專業性難題和說明文章。頭兩年的博文已由美國數學會齣版,而第三年的博文將分兩冊齣版。第一冊內容由實分析第二教程和博文中的相關資料構成。
實分析課程假定讀者對一般測度論和本科分析的基本概念已有一定的瞭解。《ε空間 I:實分析(第三年的數學博客選文)(英文版)》內容包括:測度論中的高級專題,尤其是Lebesgue-Radon-Nikodym定理和Riesz錶示定理;泛函分析專題,如Hilbert空間和Banach空間;廣義函數空間和重要的函數空間,包括Lebesgue的Lp空間和Sobolev空間。另外還討論瞭Fourier變換的一般理論。
《ε空間 I:實分析(第三年的數學博客選文)(英文版)》的第二部分談到瞭許多輔助論題,諸如Zorn引理、Caratheodory延拓定理和Banach-Tarski悖論。作者還討論瞭ε正規化推理——軟分析的一個基本技巧,《ε空間 I:實分析(第三年的數學博客選文)(英文版)》書名正取於此意。總體來說,《ε空間 I:實分析(第三年的數學博客選文)(英文版)》提供瞭比二年級研究生實分析課程豐富得多的內容。
博文的第二冊由各種專題的技術性和說明性文章組成,可以獨立閱讀。
內頁插圖
目錄
Preface
A remark on notation
Acknowledgments
Chapter 1.Real analysis
1.1.A quick review of measure and integration theory
1.2.Signed measures and the Radon-Nikodym-Lebesgue theorem
1.3.Lp spaces
1.4.Hilbert spaces
1.5.Duality and the Hahn-Banach theorem
1.6.A quick review of point-set topology
1.7.The Baire category theorem and its Banach space consequences
1.8.Compactness in topological spaces
1.9.The strong and weak topologies
1.10.Continuous functions on locally compact Hausdorff spaces
1.11.Interpolation of Lp spaces
1.12.The Fourier transform
1.13.Distributions
1.14.Sobolev spaces
1.15.Hausdorff dimension
Chapter 2.Related articles
2.1.An alternate approach to the Caratheodory extension theorem
2.2.Amenability, the ping-pong lemma, and the Banach-
Tarski paradox
2.3.The Stone and Loomis-Sikorski representation theorems
2.4.Well-ordered sets, ordinals, and Zorn's lemma
2.5.Compactification and metrisation
2.6.Hardy's uncertainty principle
2.7.Create an epsilon of room
2.8.Amenability
Bibliography
Index
前言/序言
In February of 2007, I converted my "What's new" web page of research updates into a blog at terrytao .wordpress.com. This blog has since grown and evolved to cover a wide variety of mathematical topics, ranging from my own research updates, to lectures and guest posts by other mathematicians, to open problems, to class lecture notes, to expository articles at both basic and advanced levels.
With the encouragement of my blog readers, and also of the AMS, I published many of the mathematical articles from the first two years of the blog as [Ta2008] and [Ta2009], which will henceforth be referred to as Structure and Randomn,ess and Poincare's Legacies Vols, I, H. This gave me the opportunity to improve and update these articles to a publishable (and citeable) standard, and also to record some of the substantive feedback I had received on these articles'by the readers of the blog.
The current text contains many (though not all) of the posts for the third year (2009) of the blog, focusing primarily on those posts of a mathematical nature which were not contributed primarily by other authors, and which are not published elsewhere. It has been split into two volumes.
The current volume consists oflecture notes from my graduate real anal- ysis courses that I taught at UCLA (Chapter 1), together with some related material in Chapter 2. These notes cover the second part of the graduate real analysis sequence here, and therefore assume some familiarity with general measure theory (in particular, the construction of Lebesgue mea- sure and the Lebesgue integral, and more generally the material reviewed in Section 1.1), as well as undergraduate real analysis (e.g., various notions of limits and convergence). The notes then cover more advanced topics in measure theory (notably, the Lebesgue-Radon-Nikodym and Riesz representation theorems) as well as a number of topics in functional analysis, such as the theory of Hilbert and Banach spaces, and the study of key function spaces such as the Lebesgue and Sobolev spaces, or spaces of distributions.
The general theory of the Fourier transform is also discussed. In addition, a number of auxiliary (but optional) topics, such as Zorn's lemma, are discussed in Chapter 2. In my own course, I covered the material in Chapter 1 only and also used Folland's text [Fo2000] as a secondary source. But I hope that the current text may be useful in other graduate real analysis courses, particularly in conjunction with a secondary text (in particular, one that covers the prerequisite material on measure theory).
The second volume in this series (referred to henceforth as Volume H) consists of sundry articles on a variety of mathematical topics, which is onlyoccasionally related to the above course, and can be read independently.
好的,這是一份關於一本名為《ε空間 I:實分析》(An Epsilon of Room, I: Real Analysis)的圖書的詳細簡介,該書選自第三年的數學博客文章,英文原版。 --- 《ε空間 I:實分析》(An Epsilon of Room, I: Real Analysis) 選自第三年的數學博客文章 簡介 《ε空間 I:實分析》匯集瞭作者在數學專業學習第三年期間,通過博客形式深入探討和記錄的關於實分析(Real Analysis)這一核心學科的思考、解題心得與理論梳理。本書並非傳統意義上的教科書,而是一份生動的學習日誌,它忠實地反映瞭一位數學係學生在麵對“分析學基礎”這一領域時所經曆的挑戰、頓悟與知識的構建過程。 本書的重點在於對實數係統、拓撲結構、序列與級數的收斂性,以及微積分核心概念——極限、連續性、導數和積分——在更嚴格和抽象的框架下的重新審視與深入理解。作者以一種兼具個人見解和學術嚴謹性的方式,帶領讀者穿越瞭實分析的知識迷宮。 核心內容概述 第一部分:基礎的重構——實數係統與拓撲概念的奠基 實分析的起點是對我們習以為常的實數係統進行“從零開始”的精確描述。本書首先迴顧瞭有理數和無理數的構建,並著重探討瞭實數的完備性(Completeness Axiom)。作者花費大量篇幅闡述瞭為何完備性是構建整個分析大廈的基石,包括利用戴德金截分割(Dedekind Cuts)或柯西序列(Cauchy Sequences)來定義實數。 在這一部分,拓撲學的初步概念被引入。讀者將看到對鄰域(Neighborhoods)、開集(Open Sets)和閉集(Closed Sets)的細緻討論。這些抽象概念如何精確地定義瞭“接近”與“聚集”?作者通過具體的例子,如 $mathbb{R}^n$ 空間中的拓撲結構,展示瞭這些定義如何為後續的極限理論鋪平道路。重點探討瞭聚點(Limit Points)、聚點集(Derived Sets)以及緊緻性(Compactness)的定義及其在實數綫上的重要性——特彆是 Heine-Borel 定理的直觀理解與嚴格證明。 第二部分:極限與收斂的嚴格化 實分析的精髓在於其對極限(Limit)的定義。本書的博客選文對 $epsilon-delta$ 語言進行瞭詳盡的分析和應用。作者不僅展示瞭如何使用 $epsilon-delta$ 語言來證明簡單的函數極限,更重要的是,分享瞭在麵對復雜函數或多變量函數時,如何係統地構建證明框架。 序列(Sequences)和級數(Series)的收斂性是本部分的核心。讀者將迴顧各種收斂判彆法(比值檢驗、根值檢驗、積分檢驗等),但本書的價值在於,它深入探討瞭這些判彆法的理論依據。例如,為什麼柯西序列是收斂的?單調收斂定理(Monotone Convergence Theorem)和柯西收斂準則(Cauchy Criterion)在實踐中的應用邊界在哪裏?對於級數,本書著重於一緻收斂(Uniform Convergence)的概念,區分瞭逐點收斂與一緻收斂,並探討瞭一緻收斂如何保證可微性、可積性和連續性的傳遞。 第三部分:函數分析的核心——連續性、導數與積分 在確立瞭嚴謹的極限框架後,本書轉嚮瞭對函數性質的深入研究。 連續性(Continuity)的定義被提升到拓撲視角下,即原像下開集的保持。作者討論瞭連續函數在緊集上的重要性質,如最大值/最小值定理(Extreme Value Theorem)和介值定理(Intermediate Value Theorem)的嚴密證明。 導數(Derivatives)的討論側重於其局限性。本書細緻分析瞭為什麼僅僅函數在每一點都可微並不能保證其連續性(盡管在實分析的背景下,可微性通常蘊含局部連續性,但作者可能會探討更一般的例子或反例的思路)。中值定理(Mean Value Theorems)的幾何意義和代數證明是重點,特彆是羅爾定理(Rolle's Theorem)與拉格朗日中值定理(Lagrange's MVT)的邏輯聯係。 最後,黎曼積分(Riemann Integration)的理論被係統地闡述。本書不僅關注於如何計算積分,更關注於“什麼是黎曼可積”。這涉及到黎曼上和(Upper Sums)與黎曼下和(Lower Sums)的構建,以及可積性的充要條件——幾乎處處不連續點集的勒貝格測度為零。作者對那些“病態”函數(如狄利剋雷函數)的可積性分析,體現瞭對積分理論的深刻理解。 寫作風格與受眾 本書的選文源自一個數學博客,因此其敘述風格是高度個人化和探索性的。它不僅僅是知識的陳述,更是思維過程的展示。作者傾嚮於在證明的每一步停下來,探討“為什麼是這樣?”而不是僅僅接受“就是這樣”。這種風格對於讀者而言,既提供瞭清晰的證明路徑,也提供瞭應對復雜問題的思維工具。 本書適閤於: 1. 正在學習實分析的本科生:作為教科書的有力補充,提供不同視角的解釋和解題策略。 2. 準備進入研究生學習的學生:用於鞏固對分析學基礎的掌握,特彆是對抽象概念的直觀理解。 3. 數學愛好者:對嚴格的數學證明和概念構建過程感興趣的讀者,可以從中體會到數學的嚴謹之美。 《ε空間 I:實分析》是一次對數學嚴謹性與直覺之間平衡的精彩探索,它將讀者帶入那個由 $epsilon$ 和 $delta$ 構築的精確而迷人的分析世界。