Articles containing proofs | Operator theory | Hilbert space

Compact operator on Hilbert space

In the mathematical discipline of functional analysis, the concept of a compact operator on Hilbert space is an extension of the concept of a matrix acting on a finite-dimensional vector space; in Hilbert space, compact operators are precisely the closure of finite-rank operators (representable by finite-dimensional matrices) in the topology induced by the operator norm. As such, results from matrix theory can sometimes be extended to compact operators using similar arguments. By contrast, the study of general operators on infinite-dimensional spaces often requires a genuinely different approach. For example, the spectral theory of compact operators on Banach spaces takes a form that is very similar to the Jordan canonical form of matrices. In the context of Hilbert spaces, a square matrix is unitarily diagonalizable if and only if it is normal. A corresponding result holds for normal compact operators on Hilbert spaces. More generally, the compactness assumption can be dropped. As stated above, the techniques used to prove results, e.g., the spectral theorem, in the non-compact case are typically different, involving operator-valued measures on the spectrum. Some results for compact operators on Hilbert space will be discussed, starting with general properties before considering subclasses of compact operators. (Wikipedia).

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Lecture 20: Compact Operators and the Spectrum of a Bounded Linear Operator on a Hilbert Space

MIT 18.102 Introduction to Functional Analysis, Spring 2021 Instructor: Dr. Casey Rodriguez View the complete course: https://ocw.mit.edu/courses/18-102-introduction-to-functional-analysis-spring-2021/ YouTube Playlist: https://www.youtube.com/watch?v=SFDMFbzCsH0&list=PLUl4u3cNGP63micsJp_

From playlist MIT 18.102 Introduction to Functional Analysis, Spring 2021

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Functional Analysis Lecture 12 2014 03 04 Boundedness of Hilbert Transform on Hardy Space (part 1)

Dyadic Whitney decomposition needed to extend characterization of Hardy space functions to higher dimensions. p-atoms: definition, have bounded Hardy space norm; p-atoms can also be used in place of atoms to define Hardy space. The Hilbert Transform is bounded from Hardy space to L^1: b

From playlist Course 9: Basic Functional and Harmonic Analysis

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Complexification

The complexification of a real vector space. The complexification of an operator on a real vector space. Every operator on a nonzero finite-dimensional real vector space has an invariant subspace of dimension 1 or 2. Every operator on an odd-dimensional real vector space has an eigenvalue.

From playlist Linear Algebra Done Right

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Oscar Bandtlow: Spectral approximation of transfer operators

The lecture was held within the framework of the Hausdorff Trimester Program "Dynamics: Topology and Numbers": Conference on “Transfer operators in number theory and quantum chaos” Abstract:The talk will be concerned with the problem of how to approximate spectral data oftra

From playlist Conference: Transfer operators in number theory and quantum chaos

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Lecture 18: The Adjoint of a Bounded Linear Operator on a Hilbert Space

MIT 18.102 Introduction to Functional Analysis, Spring 2021 Instructor: Dr. Casey Rodriguez View the complete course: https://ocw.mit.edu/courses/18-102-introduction-to-functional-analysis-spring-2021/ YouTube Playlist: https://www.youtube.com/watch?v=BctaYoR9tOY&list=PLUl4u3cNGP63micsJp_

From playlist MIT 18.102 Introduction to Functional Analysis, Spring 2021

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Lecture 19: Compact Subsets of a Hilbert Space and Finite-Rank Operators

MIT 18.102 Introduction to Functional Analysis, Spring 2021 Instructor: Dr. Casey Rodriguez View the complete course: https://ocw.mit.edu/courses/18-102-introduction-to-functional-analysis-spring-2021/ YouTube Playlist: https://www.youtube.com/watch?v=PBMyBVPRtKA&list=PLUl4u3cNGP63micsJp_

From playlist MIT 18.102 Introduction to Functional Analysis, Spring 2021

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Determinant of an Operator and of a Matrix

Determinant of an operator. An operator is not invertible if and only if its determinant equals 0. Formula for the characteristic polynomial in terms of determinants. Determinant of a matrix. Connection between the two notions of determinant.

From playlist Linear Algebra Done Right

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Jens Kaad: Exterior products of compact quantum metric spaces

Talk by Jens Kaad in Global Noncommutative Geometry Seminar (Europe) http://www.noncommutativegeometry.nl/ncgseminar/ on November 24, 2020.

From playlist Global Noncommutative Geometry Seminar (Europe)

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Lara Ismert: "Heisenberg Pairs on Hilbert C*-modules"

Actions of Tensor Categories on C*-algebras 2021 "Heisenberg Pairs on Hilbert C*-modules" Lara Ismert - Embry-Riddle Aeronautical University, Mathematics Abstract: Roughly speaking, a Heisenberg pair on a Hilbert space is a pair of self-adjoint operators (A,B) which satisfy the Heisenber

From playlist Actions of Tensor Categories on C*-algebras 2021

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William B. Johnson: Ideals in L(L_p)

Abstract: I’ll discuss the Banach algebra structure of the spaces of bounded linear operators on ℓp and Lp := Lp(0,1). The main new results are 1. The only non trivial closed ideal in L(Lp), 1 ≤ p [is less than] ∞, that has a left approximate identity is the ideal of compact operators (joi

From playlist Analysis and its Applications

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Markus Haase : Operators in ergodic theory - Lecture 3 : Compact semigroups and splitting theorems

Abstract : The titles of the of the individual lectures are: 1. Operators dynamics versus base space dynamics 2. Dilations and joinings 3. Compact semigroups and splitting theorems Recording during the thematic meeting : "Probabilistic Aspects of Multiple Ergodic Averages " the December 8

From playlist Dynamical Systems and Ordinary Differential Equations

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Categorical aspects of vortices (Lecture 1) by Niklas Garner

PROGRAM: VORTEX MODULI ORGANIZERS: Nuno Romão (University of Augsburg, Germany) and Sushmita Venugopalan (IMSc, India) DATE & TIME: 06 February 2023 to 17 February 2023 VENUE: Ramanujan Lecture Hall, ICTS Bengaluru For a long time, the vortex equations and their associated self-dual fie

From playlist Vortex Moduli - 2023

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Math 131 092116 Properties of Compact Sets

Properties of compact sets. Compact implies closed; closed subsets of compact sets are compact; collections of compact sets that satisfy the finite intersection property have a nonempty intersection; infinite subsets of compact sets must have a limit point; the infinite intersection of ne

From playlist Course 7: (Rudin's) Principles of Mathematical Analysis

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Erez Lapid - 1/2 Some Perspectives on Eisenstein Series

This is a review of some developments in the theory of Eisenstein series since Corvallis. Erez Lapid (Weizmann Institute)

From playlist 2022 Summer School on the Langlands program

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Lecture 22: The Spectral Theorem for a Compact Self-Adjoint Operator

MIT 18.102 Introduction to Functional Analysis, Spring 2021 Instructor: Dr. Casey Rodriguez View the complete course: https://ocw.mit.edu/courses/18-102-introduction-to-functional-analysis-spring-2021/ YouTube Playlist: https://www.youtube.com/watch?v=-sfaHVFWBU8&list=PLUl4u3cNGP63micsJp_

From playlist MIT 18.102 Introduction to Functional Analysis, Spring 2021

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Eva Gallardo Gutiérrez: The invariant subspace problem: a concrete operator theory approach

Abstract: The Invariant Subspace Problem for (separable) Hilbert spaces is a long-standing open question that traces back to Jonhn Von Neumann's works in the fifties asking, in particular, if every bounded linear operator acting on an infinite dimensional separable Hilbert space has a non-

From playlist Analysis and its Applications

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Schemes 46: Differential operators

This lecture is part of an online algebraic geometry course on schemes, based on chapter II of "Algebraic geometry" by Hartshorne. In this lecture we define differential operators on rings, and calculate the universal (normalized) differential operator of order n. As a special case we fin

From playlist Algebraic geometry II: Schemes

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Countable set | Functional analysis | Mercer's theorem | Functional calculus | Operator norm | Rayleigh quotient | Self-adjoint operator | Separable space | Spectral theorem | Topology | Strong operator topology | Zorn's lemma | Subnormal operator | Bounded operator | Banach space | Unitary operator | Stone–Weierstrass theorem | C*-algebra | Polarization identity | Spectral theory of compact operators | Normal operator | Banach–Alaoglu theorem | Spectrum (functional analysis) | Orthonormal basis | Calkin algebra | Hyponormal operator | Direct sum | Compact operator | Hilbert space | Lp space | Weak convergence (Hilbert space) | Measure (mathematics) | Finite-rank operator | Hilbert–Schmidt operator | Relatively compact subspace | Continuous functional calculus | Orthogonal complement