---
title: Adjoint Operators
parent: Unbounded Operators
nav_order: 1
published: false
description: >
  The Hellinger–Toeplitz Theorem states that an everywhere-defined symmetric
  operator on a Hilbert space is bounded. We give a proof using the Uniform
  Boundedness Theorem. We give another proof using the Closed Graph Theorem.
# spellchecker:dictionaries latex
# spellchecker:words Hellinger Toeplitz innerp hilb Schwarz functionals enspace Riesz
---

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