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2 unusual facts about Banach–Tarski paradox


Banach–Tarski paradox

As Stan Wagon points out at the end of his monograph, the Banach–Tarski paradox has been more significant for its role in pure mathematics than for foundational questions: it motivated a fruitful new direction for research, the amenability of groups, which has nothing to do with the foundational questions.

Banach and Tarski explicitly acknowledge Giuseppe Vitali's 1905 construction of the set bearing his name, Hausdorff's paradox (1914), and an earlier (1923) paper of Banach as the precursors to their work.


Banach measure

In mathematics, Banach measure in measure theory may mean a real-valued function on an algebra of all subsets of a set (for example, all subsets of the plane), by means of which a rigid, finitely additive area can be defined for every set, even when a set does not have a true geometric area.

Banach space

It follows from the Hahn–Banach separation theorem that the weak topology is Hausdorff, and that a norm-closed convex subset of a Banach space is also weakly closed.

Dunford–Pettis property

In functional analysis, the Dunford–Pettis property, named after Nelson Dunford and B. J. Pettis, is a property of a Banach space stating that all weakly compact operators from this space into another Banach space are completely continuous.

Infinite-dimensional Lebesgue measure

Compact sets in Banach spaces may also carry natural measures: the Hilbert cube, for instance, carries the product Lebesgue measure.

Komura

Kōmura's theorem, result on the differentiability of absolutely continuous Banach space-valued functions

Lasers and aviation safety

In one case, David Banach of New Jersey was charged under federal Patriot Act anti-terrorism laws, after he allegedly shone a laser pointer at aircraft.

Mohamed Amine Khamsi

He completed his PhD, entitled "La propriété du point fixe dans les espaces de Banach et les espaces Metriques", at the Pierre-and-Marie-Curie University in May 1987 under the supervision of Gilles Godefroy.

Non-measurable set

In 1989, A. K. Dewdney published a letter from his friend Arlo Lipof in the Computer Recreations column of the Scientific American where he describes an underground operation "in a South American country" of doubling gold balls using the Banach–Tarski paradox.

Norman Leto

Norman Leto (Łukasz Banach, born in 1980, Bochnia) An artist, self-educated in the field of video, film and new media.

Port Jervis, New York

Ed and Lou Banach, 1984 Summer Olympics wrestling gold medalists lived in Port Jervis and graduated from Port Jervis Senior High School.

Zorn's lemma

# Banach's extension theorem which is used to prove one of the most fundamental results in functional analysis, the Hahn–Banach theorem


see also