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Set Theory

Logic, Foundations and Set Theory

Set theory is the branch of mathematical logic that studies sets, informally described as collections of objects, along with their sizes, structures and the axioms that can found the rest of mathematics upon them. It emerged in the 1870s through the work of Georg Cantor and Richard Dedekind. 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
What are the possible sizes of infinite collections, and what axioms can consistently and completely found the rest of mathematics on the notion of a set? 1
Key Debate
Whether the axiom of choice, which guarantees a selection function for any collection of nonempty sets without constructing one, should be accepted as a foundational axiom. Zermelo-Fraenkel set theory adopts it as standard (ZFC), but constructivist mathematicians reject the non-computable objects it entails, and Bertrand Russell's discovery that unrestricted set formation produces contradictions forced the field away from naive set theory entirely. 1
Classification
Pure or Applied
Pure Mathematics 1
Connections

Associated With

Founder of set theory, 1870s.

Source Set Theory (Wikipedia)

Includes

Source Wikipedia: Aronszajn tree
Source Axiom of Infinity (Wikipedia)
Source Beth Number (Wikipedia)
Bijection, Concepts
Source Borel determinacy theorem (Wikipedia)
Source Cantor Set (Wikipedia)
Source Cardinality of the Continuum (Wikipedia)
Source Constructible Universe (Wikipedia)
Source Easton's theorem, Wikipedia
Empty Set, Concepts
Source Erdos-Rado theorem (Wikipedia)
Source Fodor's lemma, Wikipedia
Source Inaccessible cardinal (Wikipedia)
Source Measurable cardinal (Wikipedia)
Multiset, Concepts
Ordered Pair, Concepts
Source Wikipedia: Ordinal number
Source Solovay model, Wikipedia
Source Wikipedia: Tree (set theory)
Source Thoralf Skolem (Wikipedia)
Source Wikipedia: Von Neumann universe
Source Woodin cardinal (Wikipedia)
Sources
1. Set Theory (Wikipedia)
Wikipedia
  • Lead and origins sections
    the branch of mathematical logic that studies sets, which can be informally described as collections of objects
  • Origins and central questions
    Cantor is commonly considered the founder of set theory
  • Notable debates section
    Let R be the set of all sets that are not members of themselves
  • Associated With: Georg Cantor, Origins section
    Cantor is commonly considered the founder of set theory
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Cantor Set (Wikipedia)
Wikimedia FoundationIncludes: Cantor SetView the Source
Wikipedia: Tree (set theory)
Includes: Suslin Tree, Lead sentenceView the Source
Woodin cardinal (Wikipedia)
Includes: Woodin Cardinal, Lead sentence
Quote, Includes: Woodin Cardinal, Lead sentence
In set theory, a Woodin cardinal (named for W.
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Borel determinacy theorem (Wikipedia)
Includes: Borel Determinacy Theorem, Lead sentence
Quote, Includes: Borel Determinacy Theorem, Lead sentence
In descriptive set theory, the Borel determinacy theorem states that any Gale-Stewart game whose payoff set is a Borel set is dete
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Beth Number (Wikipedia)
Includes: Beth number, Lead sentence
Quote, Includes: Beth number, Lead sentence
In mathematics, particularly in set theory, the beth numbers form a certain (unset) sequence of infinite cardinal numbers (also kn
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Wikipedia: Ordinal number
Includes: Ordinal Number, Lead sentence
Quote, Includes: Ordinal Number, Lead sentence
In set theory, an ordinal number, or ordinal, is a generalization of ordinal numerals (first, second, nth, etc.) aimed to extend e
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Wikipedia: Von Neumann universe
Includes: Von Neumann Universe, Lead sentence
Quote, Includes: Von Neumann Universe, Lead sentence
In set theory and related branches of mathematics, the von Neumann universe, or von Neumann hierarchy of sets, denoted by V, is th
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Wikipedia: Aronszajn tree
Includes: Aronszajn Tree, Lead sentence
Quote, Includes: Aronszajn Tree, Lead sentence
In set theory, an Aronszajn tree is a tree of uncountable height with no uncountable branches and no uncountable levels.
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Inaccessible cardinal (Wikipedia)
Includes: Inaccessible Cardinal, Lead sentence
Quote, Includes: Inaccessible Cardinal, Lead sentence
In set theory, a cardinal number is a strongly inaccessible cardinal if it is uncountable, regular, and a strong limit cardinal.
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Measurable cardinal (Wikipedia)
Includes: Measurable Cardinal, Lead sentence
Quote, Includes: Measurable Cardinal, Lead sentence
In mathematics, specifically in set theory, a measurable cardinal is a certain kind of large cardinal number.
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Erdos-Rado theorem (Wikipedia)
Includes: Erdos-Rado Theorem, Lead sentenceView the Source
Fodor's lemma, Wikipedia
Includes: Fodor's Lemma, Lead sentence
Quote, Includes: Fodor's Lemma, Lead sentence
In mathematics, particularly in set theory, Fodor's lemma (or the pressing-down lemma) states: In modern parlance, the nonstationa
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Solovay model, Wikipedia
Includes: Solovay's Theorem, Lead sentence
Quote, Includes: Solovay's Theorem, Lead sentence
In the mathematical field of set theory, the Solovay model is a model constructed by Robert M.
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Easton's theorem, Wikipedia
Includes: Easton's Theorem, Lead sentence
Quote, Includes: Easton's Theorem, Lead sentence
In set theory, Easton's theorem is a result on the possible cardinal numbers of powersets.
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Cardinality of the Continuum (Wikipedia)
Includes: Cardinality of the Continuum, Lead sentenceView the Source
Axiom of Infinity (Wikipedia)
Includes: Axiom of Infinity, Lead sentence
Quote, Includes: Axiom of Infinity, Lead sentence
In axiomatic set theory and the branches of mathematics and philosophy that use it, the axiom of infinity is one of the axioms of
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Constructible Universe (Wikipedia)
Includes: Constructible Universe, Lead sentenceView the Source
Thoralf Skolem (Wikipedia)
Includes: Thoralf Skolem, Lead paragraph [in-branch]
Quote, Includes: Thoralf Skolem, Lead paragraph [in-branch]
set theory
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