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Functional Analysis

Analysis

Functional analysis is the branch of mathematical analysis that studies vector spaces of functions equipped with limit-related structure, such as a norm or an inner product, together with the linear maps between them that respect that structure. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
Central Question
Which infinite-dimensional vector spaces of functions carry enough limit structure, a norm or an inner product complete under it, to let the tools of linear algebra and calculus be applied to them together. 1
Key Debate
Whether every bounded linear operator on a Hilbert space has a proper invariant subspace, a question about the operators the field's own foundational spaces support that remains an open problem in functional analysis despite the field's century of development. 1
Classification
Pure or Applied
Pure Mathematics 1
Connections

Associated With

Includes

Sources
1. Wikipedia: Functional Analysis
Wikimedia Foundation
  • Lead section
    the study of vector spaces endowed with some kind of limit-related structure
  • Normed vector spaces section
    These spaces are of fundamental importance in many areas, including the mathematical formulation of quantum mechanics, machine learning, partial differential equations, and Fourier analysis.
  • Hilbert spaces section, invariant subspace problem
    One of the open problems in functional analysis is to prove that every bounded linear operator on a Hilbert space has a proper invariant subspace.
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Stone-Weierstrass Theorem (Wikipedia)
Wikipedia
  • Open problems section
    One of the open problems in functional analysis is to prove that every bounded linear operator on a Hilbert space has a proper invariant subspace.
  • History section
    Hilbert spaces were studied beginning in the first decade of the 20th century by David Hilbert (after whom they are named)
  • lead paragraph
    In mathematical analysis, the Weierstrass approximation theorem states that every continuous function defined on a closed interval [a, b] can be uniformly approximated as closely as desired by a polynomial function.
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