**CONTENT:**

(a) Types of functions (one-to-one, one-to-many, many-to-one, many-to-many)

(b) Function as a mapping

(c) Determination of the rule of a given mapping/function.

A mapping is simply an association or a relation between two sets

A function is a relation in which each element of the domain has one and only one image in the co-domain. One-to-one and many-to-one relation are therefore functions.

Note:

- If there exists at least an element in the domain that does not have an image in the co-domain, then it is not a mapping.
- If an element in the domain has 2 or more images in co-domain, then it is not a mapping.

Thus, for a relation to be a mapping; it must be that:

***Every element of the domain has an image in the co-domain**

***The image of every element of the domain is unique**

Note: All functions are relations but not all relations are functions

Many – to – many relation is not a function since some elements of the domain have more than one image.

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