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Unbounded Self Adjoint Operators and Stones Theorem

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1 · Prerequisites
Abstract Algebra
Combinatorics
Complex Analysis
Coxeter Groups
Functional Analysis
Linear Algebra
Measure Theory
Real Analysis
Set Theory
Topology
2 · Logical flowchart

3 · Items

Definition

Unbounded linear operators: domain, graph and extension

Definition

Densely defined, closed and closable operators, and cores

Theorem

Closure of a closable operator

Definition

Adjoint of a densely defined operator

Lemma

The adjoint is well defined, closed, and reverses inclusions

Theorem

Closability is equivalent to density of the adjoint domain

Definition

Symmetric, self-adjoint and essentially self-adjoint operators

Counterexample

A symmetric closed operator that is not self-adjoint

Definition

Resolvent and spectrum of an unbounded operator

Theorem

Resolvent of a self-adjoint operator: nonreal resolvents and the estimate

Theorem

Range criterion for self-adjointness

Definition

Cayley transform of a self-adjoint operator

Theorem

Cayley correspondence between self-adjoint operators and unitaries

Definition

Integral of a measurable function against a projection-valued measure

Lemma

The unbounded PVM integral is densely defined, closed and normal

Theorem

Spectral theorem for unbounded self-adjoint operators (PVM form)

Theorem

Unbounded Borel functional calculus: domains, products, spectral mapping

Definition

Strongly continuous one-parameter unitary group

Definition

Infinitesimal generator of a unitary group

Lemma

A self-adjoint operator generates a strongly continuous unitary group

Lemma

Laplace resolvents of a unitary group

Lemma

The generator of a unitary group is closed and skew-adjoint

Theorem

Stone's theorem: unitary groups and self-adjoint generators

Definition

Deficiency subspaces and deficiency indices

Theorem

Von Neumann parameterization of self-adjoint extensions

Corollary

Existence of self-adjoint extensions is equality of deficiency indices

Definition

Pure point, absolutely continuous and singular continuous spectral subspaces

Theorem

Canonical decomposition into pure point, absolutely continuous and singular continuous parts

Definition

Relative boundedness with respect to an operator

Lemma

Second resolvent identity for a closed perturbation

Theorem

Kato-Rellich theorem

Definition

Discrete and essential spectrum of a self-adjoint operator

Theorem

Weyl criterion for the essential spectrum

Definition

Relative compactness with respect to an operator

Theorem

Weyl's theorem: invariance of the essential spectrum

Definition

Norm and strong resolvent convergence

Lemma

The resolvent star algebra is dense in C₀(R)

Theorem

Continuous functional calculus under resolvent convergence

Corollary

Unitary groups converge under strong resolvent convergence

Lemma

Spectral form domain and core of a semibounded operator

Theorem

Min-max principle below the essential spectrum

Sources