In previous lessons, we learned that a set is a group of objects, and that Venn diagrams can be used to illustrate both set relationships and logical relationships.
Example 1: Given A = {1, 2, 5, 6} and B = {3, 9}, what is the relationship between these sets?
A and B have no elements in common. This relationship is shown in the Venn diagram below.
Answer: A and B have no elements in common. These sets do not overlap.
VENN Diagrams
A Venn diagram in which the area of each shape is proportional to the number of elements it contains is called an area-proportional or scaled Venn diagram.
Set Operations : The four basic operations are:
1. Union of Sets
2. Intersection of sets
3. Complement of the Set
4. Cartesian Product of sets
The union of two sets is a set containing all elements that are in
or in (possibly both). For example, . Thus, we can write if and only if or . Note that . In Figure 1.4, the union of sets and is shown by the shaded area in the Venn diagram.