> Why can't you use the natural numbers? Because the rest of the axioms of ZF aren't sufficient to construct them. > what's an example of a theorem that canno

> Why can't you use the natural numbers? Because the rest of the axioms of ZF aren't sufficient to construct them. > what's an example of a theorem that cannot be proven without the Axiom of Infinity? That there exists a set equal to the natural numbers up to isomorphism, that there exist well-defined operations "+", "-", "*", "/" with usual semantics, that there exist the usual sets of rational, real, complex numbers.