Operations with Sets
Complement
The complement of a set S is consists of everything that is not in S.
Union
The union of two sets is everything that is in either set; that is, anything colored (blue, yellow, or green).
Intersection
The intersection of two sets is everything that is in both sets; that is, anything colored both blue and yellow, namely green.
Cardinality of the Union of Two Sets
The cardinality of the union of two sets can be found by adding the cardinality of the given sets and then subtracting the cardinality of the number of of elements in the intersection.