<*mathematics*> A function f : A -> B is surjective or onto or a
surjection if f A = B. I.e. f can return any value in B.
This means that its image is its codomain.

Only surjections have right inverses, f' : B -> A where f (f' x) = x since if f were not a surjection there would be elements of B for which f' was not defined.

See also bijection, injection.

Last updated: 1995-05-27

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Sure « surfing « SURGE « **surjection** » surjective » surrogate key » suspension

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Copyright Denis Howe 1985