In mathematics, a bijective function or bijection is a function "f" : "A" → "B" that is both an injection and a surjection. This is equivalent to the following statement: for every element "b" in the codomain "B", there is "exactly" one element "a" in the domain "A" such that "f"("a")="b". Another name for bijection is 1-1 correspondence (read "one-to-one correspondence).