Exam-style question
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Explain the meaning of the function type f: A → B. In your answer, distinguish between the domain, the co-domain, the argument type and the result type.
Model answer
What a good answer should say
- The notation describes a function named f whose argument type is A and whose result type is B.
- A is called the domain, meaning that input values are chosen from A.
- B is called the co-domain, meaning that output values are chosen from B.
- Each element in A is assigned an output in B, but not every member of B must be used as an output.
Explanation
Why this works
A complete answer identifies A as both the argument type and domain, and B as both the result type and co-domain. It should also state that the co-domain can contain members that are never produced.
Common mistake
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