Sets

4. Null Set

It is convenient to introduce the concept of the empty set, that is, a set which contains no elements. This set is sometimes called the null set.

We say that such a set is void or empty, and we denote its symbol ∅

Example 6.1: Let A be the set of people in the world who are older than 200years. According to known statistics A is the null set.

Example 6.2: Let B = {x | x²= 4, x is odd}, Then B is the empty set.