ABSTRACT
Function, domain, image, pre-image. A correspondence f between two sets X and Y such that with each element x 2 X is associated exactly one element y 2 Y is called a function from X to Y and is denoted by y = f (x) : X ! Y , or in short notation f (x) or even f . The set X is called the domain of f (we also say f is dened on X) and the set Y is called the codomain. The part of Y that contains all values f (x) for x 2 X is called the image (or range) of f and the usual notation is f (X). Respectively, the image of any set S X is denoted by f (S).
