is defined as a correspondence between two variables.

A set of ordered pairs (x, y) where x is related to y.

The set of all values of the independent variable (x) is the 

The set of all values of the dependent variable is the

One-One

One-Many

Many-One

Many-Many

A correspondence between variables x and y, that associates with each element  of y 

Representation of function 

All functions are Relations

All relations are functions

not all relations are functions

It is a method that is used to determine whether a given relation is a function or not.