CSCE 235

Handout 8: Sets

February 10, 2003 

 

Examples of Sets

 

Names

Definitions

Natural numbers

N = { 0, 1, 2, 3, 4, 5, …}

All integers (positive, zero, negative)

Z = { …, -3, -2, -1, 0, 1, 2, 3, 4, 5, …}

Positive integers

Z+ = { 1, 2, 3, 4, 5, …}

Rational numbers

Q = {m/n |  and  and }

Irrational numbers

A number which cannot be written in the form m/n with both m and n integers

Real numbers

R, rational or not. 

Complex numbers

C have the form a+bi where a and b are real numbers and .  That is: 

Note:  Z+NZQR

 

Intervals

 

Notation for some special subsets of R, called intervals.  For  with a < b, we define

             closed 

             open

             half open

             half open

 

Laws of Algebra of Sets

 

Laws

Representation

Commutative Laws

              

Associative Laws

                    

Distributive Laws

              

Idempotent Laws

        

Identity Laws

       

Domination Laws

       

Double Complementation

Complement Laws

                         

DeMorgan Laws

                   

Absorption Laws