A function \(f\) from set \(A\) to set \(B\) is called an injection and \(f\) is said to be injective if each element in \(A\) maps to a different element in \(B\).
In symbols, \(f\) is injective if \(f(a)=f(b)\) implies that \(a=b\).
An injective function is also known as a one-to-one or one-one (both read as ‘one to one’) function.
