Naive set theory no relation extensional definition
Naive set theory
The foremost property of a set is that it can have elements, also called members. Two sets are equal when they have the same elements. More precisely, sets A and B are equal if every element of A is an element of B, and every element of B is an element of A; this property is called the extensionality of sets.The simple concept of a set has proved enormously useful in mathematics, but paradoxes arise if no restrictions are placed on how sets can be constructed:An intensional definition uses a rule to determine membership. Semantic definitions and definitions using set-builder notation are examples.
An extensional definition describes a set by listing all its elements. Such definitions are also called enumerative.
An ostensive definition is one that describes a set by giving examples of elements; a roster involving an ellipsis would be an example.
no relation