# Set Theory - Bijection function (One-to-one relationship)

## About

A Bijection is a mathematical / set function between the elements of two sets (ie binary function) where

- each element of one set is paired with exactly one element of the other set,
- each element of the other set is paired with exactly one element of the first set.
- there are no unpaired elements

This function is also known as:

- the one-to-one relationship
- or invertible function

## Articles Related

## Example

- A bijection (Ref

- Not a bijection

## Properties

A function f: R → R is bijective if and only if its graph meets every horizontal and vertical line exactly once.