• This article contains a discussion of paradoxes of set theory. As with most mathematical paradoxes, they generally reveal surprising and counter-intuitive...
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  • have set-like collections while differing from sets so as to avoid paradoxes, especially Russell's paradox (see § Paradoxes). The precise definition of "class"...
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  • Thumbnail for Set theory
    After the discovery of paradoxes within naive set theory (such as Russell's paradox, Cantor's paradox and the Burali-Forti paradox), various axiomatic systems...
    54 KB (6,575 words) - 19:15, 10 June 2025
  • set theory is inconsistent. Prior to Russell's paradox (and to other similar paradoxes discovered around the time, such as the Burali-Forti paradox)...
    32 KB (4,621 words) - 14:05, 26 May 2025
  • several paradoxes—presumably had in mind. Axiomatic set theory was developed in response to these early attempts to understand sets, with the goal of determining...
    35 KB (4,774 words) - 22:32, 25 May 2025
  • formulate a theory of sets free of paradoxes such as Russell's paradox. Today, Zermelo–Fraenkel set theory, with the historically controversial axiom of choice...
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  • In set theory, Cantor's paradox states that there is no set of all cardinalities. This is derived from the theorem that there is no greatest cardinal...
    5 KB (734 words) - 07:41, 20 November 2023
  • Thumbnail for Intersection (set theory)
    In set theory, the intersection of two sets A {\displaystyle A} and B , {\displaystyle B,} denoted by A ∩ B , {\displaystyle A\cap B,} is the set containing...
    12 KB (1,734 words) - 23:16, 26 December 2023
  • Richard's paradox is a semantical antinomy of set theory and natural language first described by the French mathematician Jules Richard in 1905. The paradox is...
    12 KB (1,800 words) - 09:55, 18 November 2024
  • contradict themselves Banach–Tarski paradox – Geometric theorem Galileo's paradox – Paradox in set theory Paradoxes of set theory Pigeonhole principle – If there...
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  • in the development of modern logic and set theory. Thought experiments can also yield interesting paradoxes. The grandfather paradox, for example, would...
    24 KB (2,737 words) - 06:28, 27 April 2025
  • Non-well-founded set theories are variants of axiomatic set theory that allow sets to be elements of themselves and otherwise violate the rule of well-foundedness...
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  • "Set Theory", Stanford Encyclopedia of Philosophy, Metaphysics Research Lab, Stanford University Suppes, Patrick (1972) [1960], Axiomatic Set Theory,...
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  • set theory (sometimes denoted by Z-), as set out in a seminal paper in 1908 by Ernst Zermelo, is the ancestor of modern Zermelo–Fraenkel set theory (ZF)...
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  • Thumbnail for Skolem's paradox
    Skolem's paradox is the apparent contradiction that a countable model of first-order set theory could contain an uncountable set. The paradox arises from...
    28 KB (3,331 words) - 11:59, 18 March 2025
  • of mathematics, von Neumann–Bernays–Gödel set theory (NBG) is an axiomatic set theory that is a conservative extension of Zermelo–Fraenkel–choice set...
    97 KB (15,666 words) - 02:01, 18 March 2025
  • Thumbnail for Complement (set theory)
    In set theory, the complement of a set A, often denoted by A c {\displaystyle A^{c}} (or A′), is the set of elements not in A. When all elements in the...
    12 KB (1,515 words) - 07:59, 27 January 2025
  • In set theory, a field of mathematics, the Burali-Forti paradox demonstrates that constructing "the set of all ordinal numbers" leads to a contradiction...
    6 KB (880 words) - 13:20, 24 January 2025
  • In set theory, Kőnig's theorem states that if the axiom of choice holds, I is a set, κ i {\displaystyle \kappa _{i}} and λ i {\displaystyle \lambda _{i}}...
    8 KB (1,232 words) - 18:17, 6 March 2025
  • This list includes well known paradoxes, grouped thematically. The grouping is approximate, as paradoxes may fit into more than one category. This list...
    57 KB (7,957 words) - 16:52, 9 June 2025
  • In set theory and related branches of mathematics, the von Neumann universe, or von Neumann hierarchy of sets, denoted by V, is the class of hereditary...
    21 KB (2,811 words) - 12:49, 27 December 2024
  • Thumbnail for Union (set theory)
    In set theory, the union (denoted by ∪) of a collection of sets is the set of all elements in the collection. It is one of the fundamental operations...
    14 KB (1,989 words) - 08:46, 6 May 2025
  • included as one of its members). This paradox prevents the existence of a universal set in set theories that include either Zermelo's axiom of restricted comprehension...
    10 KB (1,327 words) - 06:43, 21 May 2024
  • set theory (KP), pronounced /ˈkrɪpki ˈplɑːtɛk/, is an axiomatic set theory developed by Saul Kripke and Richard Platek. The theory can be thought of as...
    10 KB (1,586 words) - 11:54, 3 May 2025
  • paradox Liar paradox List of paradoxes Richard's paradox Zermelo–Fraenkel set theory Curry, Haskell B. (Sep 1942). "The Inconsistency of Certain Formal...
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  • philosophy of mathematics NP (complexity) – Complexity class used to classify decision problems Paradoxes of set theory Transcomputational problem – Class of computational...
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  • Thumbnail for Cardinality
    Cardinality (redirect from Set modulus)
    of the original paradoxes that added to the need for a formalized set theory to avoid these paradoxes. This paradox is usually resolved in formal set...
    76 KB (10,345 words) - 20:29, 17 June 2025
  • sentences of a given language cannot be defined within that language. To formulate linguistic theories without semantic paradoxes such as the liar paradox, it...
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  • condition, leading to paradoxes such as Russell's paradox in naïve set theory. naive set theory 1.  Naive set theory can mean set theory developed non-rigorously...
    91 KB (11,628 words) - 12:22, 21 March 2025
  • Thumbnail for Paradox of tolerance
    Less well known [than other paradoxes] is the paradox of tolerance: Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited...
    25 KB (2,902 words) - 14:22, 19 June 2025