Let f:A--->B be a function. Prove that f is surjective if and only if f^(-1)(W) does not equal the empty set for all nonempty sets W of B. I really do not know what to do with this. Thanks for your help everyone
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Originally Posted by steph3824 Let f:A--->B be a function. Prove that f is surjective if and only if f^(-1)(W) does not equal the empty set for all nonempty sets W of B. Because is sujective . Is it possible for to be empty? Likewise if must be surjective?
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