Question

What is the difference between injective and surjective?

Answer 1

Answer:

In mathematics, an injective function or injection or one-to-one function is a function that always maps distinct elements of its domain to distinct elements of its codomain. In other words, every element of the function's codomain is the image of at most one element of its domain.

In mathematics, a function f from a set X to a set Y is surjective, or a surjection, if for every element y in the codomain Y of f there is at least one element x in the domain X of f such that f(x) = y. It is not required that x be unique; the function f may map one or more elements of X to the same element of Y