Introduction to Injective and Surjective Functions

A detailed tutorial on injective and surjective functions. Step by step tutorial including several examples of injective and surjective functions for reference.

When given a function, there are two properties it can possess: it can be either injective or surjective. An injective function is a function that associates distinct arguments in one domain with distinct values in one codomain, and every unique argument produces a unique result. A surjective function is a function where the range is equal to the codomain. A surjective function is also called a surjection or said to be onto. For both cases, the function could be bijective if all elements in the codomain are mapped, which means that it would be both injective and surjective at the same time.