Two sets are equal iff they have the same elements.
Axiom of extensionality
Related concepts
- Universal quantifier
- Biconditional (IFF)
- Axiom of pairing
- Axiom of union
- Axiom schema of separation
- Axiom schema of replacement
- Axiom of foundation (regularity)
- Axiom of choice
- Axiom of power set
- Category
- Forcing & independence proofs
- Inner model L (Gödel)
- Möbius function of a poset
- Inclusion-exclusion principle
- Gleason's theorem