In general, the set of all elements belonging to A and B is called the intersection of A and B, and it is recorded as (pronounced "A over B").

In general, the set consisting of all elements belonging to A or B is called the union of A and B, and is recorded as "A and B".

Let a = {4 4,5,6,8} and b = {3 3,5,7,8}.

Then A crosses B = {5,8} (male * * *).

A and B = {3,4,5,6,7,8} (both are always * * * (a repetition))