 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2013/discrete-mathematics-probability-and-continuous-mathematics/1/d/ii/solution

The function is surjective, also called onto, when every element of its codomain has at least one preimage:

f (A) = B ⟺ \forall b \in B \exists a \in A : f (a) = b .

The condition concerns the specified codomain, not just the formula defining the function.

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