* Naive set theory, and
* Axiomatic set theory, set theory is based on the terms and undefined relationships, and axioms that would build the whole theory of sets.
The set is a collection of certain objects which are included in one unit with a clear explanation. To declare a set, use capital letters like A, B, C etc.. While for the states of its members to use lowercase letters like a, b, c, etc..
There are four ways to express a set of
1. Enumeration: by registering all of its members (roster) is placed inside a pair of curly brackets, and among each of its members separated by commas. Example:
A = (a, i, u, e, o)
2. Standard symbols: the use of certain symbols that have been agreed. Example:
P is the set of positive integers
Z is the set of integers
R is the set of real numbers
C is the set of complex numbers
3. Forming a set of notation: by writing the general characteristics or general properties (roles) of the members. Example:
A = (x | x is the set of integers)
4. Venn diagram: graphically presents the set with each set is described as a circle and have set the universe (U) fixative DNG rectangular.