## Theorem 2.2.10: Cantor-Bernstein

Let

The proof is not so easy - it will be added later, sorry.
**A**and**B**be two sets. If there exists a one-to-one function*f*from**A**to**B**and another one-to-one function*g*from**B**to**A**, then*card(*.**A**) = card(**B**)