VDict mobile



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.
(1995-05-27)