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Single Idea 10872

[filed under theme 4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I ]

Full Idea

Axiom of Extension: Two sets are equal if and only if they have the same elements.

Gist of Idea

Extensionality: Two sets are equal if and only if they have the same elements

Source

Brian Clegg (Infinity: Quest to Think the Unthinkable [2003], Ch.15)

Book Ref

Clegg,Brian: 'Infinity' [Robinson 2003], p.205