• U is denoted as a universe that specifies a very general collection of elements such as all people, all car or all points in a 2D plane
• S is the universe for elements that fulfill a certain condition
– The set of people older than 75 years
– The set of points contained within some region
• S = {e | condition}
• For any type of set S, discrete or not, the relation between an element e of the
universe and the set will be expressed by:
– e S if e is a member of S
– e S if e is not a member of S