Friday, July 11, 2014

Bijection, injection and surjection



 Here is an easy way to remember which is which:

Injection: 1nject1ion, i.e. 1-to-1

Surjection: as the word "sur" means "on" in French, "surjective" means that the domain A is mapped onto the codomain B, i.e. the whole codomain is covered by the image of the domain.

Bijection: as the prefix "bi" means "two", "bijective" means a function that has both properties: is both injective and surjective