Practice question · Multiple choice
Why is not every relation a function?
Hints
- Compare the definitions directly.
- A relation is any set of pairs; a function constrains how many pairs may share a first element.
Show the answer
B. A function must assign exactly one output to each input, and relations need not
Why
A relation is any subset of the Cartesian product, with no constraint. A function adds the requirement of exactly one output per input, "is a parent of" relates one person to several children, so it is a relation and not a function.
Practise Relations, Functions and Power Sets
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