In
mathematics, a
bijection,
bijective function or
one-to-one correspondence is a
function between the elements of two
sets, where every element of one set is paired with exactly one element of the other set, and every element of the other set is paired with exactly one element of the first set. There are no unpaired elements. In mathematical terms, a bijective function
f:
X →
Y is a
one-to-one (injective) and
onto (surjective) mapping of a set
X to a set
Y.