Sentence EXTENSIONALITY-PROPERTY-OF-SETS

Two sets are identical if and only if they have the same members.

Instance-Of: Sentence

Defining-Axiom:

'(=> (And (Set ?S1) (Set ?S2))
     (<=> (Forall (?X) (<=> (Member ?X ?S1) (Member ?X ?S2)))
          (= ?S1 ?S2)))

• Defined in theory: Kif-sets
• Source code: kif-sets.lisp