__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*.