a well-defined Collection of objects

o   All people with registered political preferences of republican or democrat.

o   Sets are designated by capital letters: A,B,X… and are contained in braces { }

How is set defined?

Set (2 definitions)

List definiton-List all the members of the set

Rule definition- for determining whether objects do or do not belong to the set. Ex. If X then Y- clear

of a set is a set that results from selecting sets from an original set.

o   B C A

o   Thais means

§  B is a subset of A

§  B is contained in A

§  All members of B are also members of A

o   Subset = Republicans

o   Subset = Democrats