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  2. Axiom of choice - Wikipedia

    en.wikipedia.org/wiki/Axiom_of_choice

    Many theorems provable using choice are of an elegant general character: the cardinalities of any two sets are comparable, every nontrivial ring with unity has a maximal ideal, every vector space has a basis, every connected graph has a spanning tree, and every product of compact spaces is compact, among many others. Frequently, the axiom of ...

  3. List of statements independent of ZFC - Wikipedia

    en.wikipedia.org/wiki/List_of_statements...

    The mathematical statements discussed below are provably independent of ZFC (the canonical axiomatic set theory of contemporary mathematics, consisting of the Zermelo–Fraenkel axioms plus the axiom of choice), assuming that ZFC is consistent. A statement is independent of ZFC (sometimes phrased "undecidable in ZFC") if it can neither be ...

  4. Tarski's theorem about choice - Wikipedia

    en.wikipedia.org/wiki/Tarski's_theorem_about_choice

    The opposite direction was already known, thus the theorem and axiom of choice are equivalent. Tarski told Jan Mycielski that when he tried to publish the theorem in Comptes Rendus de l'Académie des Sciences de Paris, Fréchet and Lebesgue refused to present it. Fréchet wrote that an implication between two well known propositions is not a ...

  5. Zermelo–Fraenkel set theory - Wikipedia

    en.wikipedia.org/wiki/Zermelo–Fraenkel_set_theory

    Following Kunen (1980), we use the equivalent well-ordering theorem in place of the axiom of choice for axiom 9. All formulations of ZFC imply that at least one set exists. Kunen includes an axiom that directly asserts the existence of a set, although he notes that he does so only "for emphasis". [ 6 ]

  6. Group structure and the axiom of choice - Wikipedia

    en.wikipedia.org/wiki/Group_Structure_and_the...

    Using the axiom of choice, one can show that for any family S of sets | ⋃S | ≤ | S | × sup { |s| : s ∈ S} (A). [5] Moreover, by Tarski's theorem on choice, another equivalent of the axiom of choice, | X | n = | X | for all finite n (B). Let X be an infinite set and let F denote the set of all finite subsets of X. There is a natural ...

  7. Immersion (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Immersion_(mathematics)

    Hassler Whitney initiated the systematic study of immersions and regular homotopies in the 1940s, proving that for 2m < n + 1 every map f : M m → N n of an m-dimensional manifold to an n-dimensional manifold is homotopic to an immersion, and in fact to an embedding for 2m < n; these are the Whitney immersion theorem and Whitney embedding theorem.

  8. Equivalents of the Axiom of Choice - Wikipedia

    en.wikipedia.org/wiki/Equivalents_of_the_Axiom...

    Equivalents of the Axiom of Choice is a book in mathematics, collecting statements in mathematics that are true if and only if the axiom of choice holds. It was written by Herman Rubin and Jean E. Rubin , and published in 1963 by North-Holland as volume 34 of their Studies in Logic and the Foundations of Mathematics series.

  9. Luce's choice axiom - Wikipedia

    en.wikipedia.org/wiki/Luce's_choice_axiom

    Theorem: Any matching law selection rule satisfies Luce's choice axiom. Conversely, if P ( a ∣ A ) > 0 {\displaystyle P(a\mid A)>0} for all a ∈ A ⊂ X {\displaystyle a\in A\subset X} , then Luce's choice axiom implies that it is a matching law selection rule.