The axiom of Zermelo-Fraenkel set theory which asserts the existence for any sets and of a set having and as its only elements. is called the unordered pair of and , denoted . The axiom may be stated symbolically as
Axiom of the Unordered Pair
See alsoZermelo-Fraenkel Set Theory
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ReferencesItô, K. (Ed.). "Zermelo-Fraenkel Set Theory." §33B in Encyclopedic Dictionary of Mathematics, 2nd ed., Vol. 1. Cambridge, MA: MIT Press, pp. 146-148, 1986.
Referenced on Wolfram|AlphaAxiom of the Unordered Pair
Cite this as:
Weisstein, Eric W. "Axiom of the Unordered Pair." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/AxiomoftheUnorderedPair.html