Question

Assume that X and Y are finite sets. Prove the following statement: If there is a...

Assume that X and Y are finite sets. Prove the following statement:
If there is a bijection f:X→Y then|X|=|Y|.
Hint: Show that if f : X → Y is a surjection then |X| ≥ |Y| and if f : X → Y is an injection then
|X| ≤ |Y |.

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