Book contents
- Frontmatter
- Contents
- Introduction
- 1 Complete Metric Spaces
- 2 Banach’s Principle
- 3 Picard’s Theorem
- 4 Banach Spaces
- 5 Renewal Equation in the McKendrick–von Foerster Model
- 6 Riemann Integral for Vector-Valued Functions
- 7 The Stone–Weierstrass Theorem
- 8 Norms Do Differ
- 9 Hilbert Spaces
- 10 Complete Orthonormal Sequences
- 11 Heat Equation
- 12 Completeness of the Space of Operators
- 13 Working in ℒ(𝕏)
- 14 The Banach–Steinhaus Theorem and Strong Convergence
- 15 We Go Deeper, DeeperWe Go (into the Structure of Complete Spaces)
- 16 Semigroups of Operators
- Appendix Two Consequences of the Hahn–Banach Theorem
- References
- Index
2 - Banach’s Principle
Published online by Cambridge University Press: 31 October 2024
Book contents
- Frontmatter
- Contents
- Introduction
- 1 Complete Metric Spaces
- 2 Banach’s Principle
- 3 Picard’s Theorem
- 4 Banach Spaces
- 5 Renewal Equation in the McKendrick–von Foerster Model
- 6 Riemann Integral for Vector-Valued Functions
- 7 The Stone–Weierstrass Theorem
- 8 Norms Do Differ
- 9 Hilbert Spaces
- 10 Complete Orthonormal Sequences
- 11 Heat Equation
- 12 Completeness of the Space of Operators
- 13 Working in ℒ(𝕏)
- 14 The Banach–Steinhaus Theorem and Strong Convergence
- 15 We Go Deeper, DeeperWe Go (into the Structure of Complete Spaces)
- 16 Semigroups of Operators
- Appendix Two Consequences of the Hahn–Banach Theorem
- References
- Index
Summary
Banach’s principle states that if a map T uniformly reduces the distance between points of a complete metric space, then there is a unique x such that Tx = x, called T’s fixed point. This simple statement has profound and surprising consequences, as we will see in the following chapters. For now, we will content ourselves with an example, which may appear to belong to the realm of linear algebra, but is, in fact, much easier to deal with using metric notions.
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- Information
- Functional Analysis RevisitedAn Essay on Completeness, pp. 15 - 19Publisher: Cambridge University PressPrint publication year: 2024