3.2c Complement of a Set
1. The complement of set B is the set of all elements in the universal set, ξ, which are not elements of set B, and is denoted by B’.
Example 1:
If ξ = {17, 18, 19, 20, 21, 22, 23} and
B = {17, 20, 21} then
B’ = {18, 19, 22, 23}
2. The Venn diagram below shows the relationship between B, B’ and the universal set, ξ.
The complement of set B is represented by the green colour shaded region inside the universal set, ξ, but outside set B.