VENN DIAGRAMS

In set theory we use circles and rectangles to represent sets and a combination of these is named as Venn-diagrams

Below are some examples of Venn-diagrams:

U = universal set
A = subset of U
(i.e. A is contained in U)

A' = complement of A
(i.e. all the elements of U that are not included in A)


Universal set with 2 disjoint sets A & B

U = real numbers

A = odd numbers

B = even numbers

Universal set with two intersecting sets A & B

U = real numbers

A = even numbers

B = number divisible by 5

OPERATIONS ON SETS

Union: 

Let A and B be two sets. 

The union of A and B is the set of all those elements,

Which belong to either set A or set B or to both set A and B. 

We shall use the notation: A U B (read as "A union B") to denote the union of A and B

Intersection:

Let A and B be two sets. 

The intersection of A and B is the set of only those elements that belong to both A and B. 

We shall use the notation A n B (read as "A intersection B")

CONSIDER THREE SETS A, B AND C