axiom of extensionality

One of the axioms in axiomatic set theory, equivalent to the statement that two sets are equal if and only if they contain the same elements.
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Axiom of extensionality — In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of extensionality, or axiom of extension, is one of the axioms of Zermelo Fraenkel set theory. Formal statement In the formal language of… … Wikipedia
Axiom schema of specification — For the separation axioms in topology, see separation axiom. In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom schema of specification, axiom schema of separation, subset axiom scheme or… … Wikipedia
Axiom of infinity — In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of infinity is one of the axioms of Zermelo Fraenkel set theory. Formal statement In the formal language of the Zermelo Fraenkel axioms,… … Wikipedia
Axiom of pairing — In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of pairing is one of the axioms of Zermelo Fraenkel set theory. Formal statement In the formal language of the Zermelo Frankel axioms, the … Wikipedia
Axiom of empty set — In set theory, the axiom of empty set is one of the axioms of Zermelo–Fraenkel set theory and one of the axioms of Kripke–Platek set theory. Formal statement In the formal language of the Zermelo–Fraenkel axioms, the axiom reads::exist x, forall… … Wikipedia
Axiom of union — In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of union is one of the axioms of Zermelo Fraenkel set theory, stating that, for any set x there is a set y whose elements are precisely… … Wikipedia
Axiom of power set — In mathematics, the axiom of power set is one of the Zermelo Fraenkel axioms of axiomatic set theory.In the formal language of the Zermelo Fraenkel axioms, the axiom reads::forall A , exists P , forall B , [B in P iff forall C , (C in B… … Wikipedia
Extensionality — In logic, extensionality refers to principles that judge objects to be equal if they have the same external properties. It is the opposite concept of intensionality, which is concerned with whether two descriptions are intended to be the same or… … Wikipedia
extensionality — extensionality, axiom of … Philosophy dictionary
Axiom — This article is about logical propositions. For other uses, see Axiom (disambiguation). In traditional logic, an axiom or postulate is a proposition that is not proven or demonstrated but considered either to be self evident or to define and… … Wikipedia