Set Predicates
Based on the concept of membership
Membership: x ?S
- only basic predicate - sets are black boxes otherwise
Equivalence: R = S
- x ?R ? x ?S (for all x)
- extensionality principle { 1, 4, 7} = {4, 1, 7}
Subset: R ? S
- x ?R ? x ?S (for all x)
- ( {} ? S, S ? S)