☼ Venn Diagrams : We represent sets by closed bounded figures, known as Venn diagrams. The universal set is denoted by a rectangular region and each subset of  it is shown by a closed bounded figure within this rectangle.

Case  I   :    When    A  U,    B  U    and  A  B . In this case  Venn diagram consists of  two interesting bounded figures within a rectangular region, representing A and B respectively.

We have depicted the regions of  ( A – B ),

( A  B) and  ( B – A )

■ Case  II  :   When A  U, B  U and

A B  = .

In this case, the Venn diagram consists of  two closed non-intersecting figures lying within a rectangular region.

In this case, A  B  = , A – B  =  A  & B – A = B.

■ Case  III  :   When   A    B  U.

In this case, the  Venn diagram has been shown in the adjoining figure.

Clearly, A B = B,  A B = A  &  A – B  = .

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