A Example Uncountable Set Theorem: the real numbers r are not countable(they are uncountable) How do you prove such a statement? o assume countable(so there exists bijection f) o derive contradiction(some element not mapped to by f o technique is called diagonalization( Cantor)Example Uncountable Set Theorem: the real numbers R are NOT countable (they are “uncountable”). ◼ How do you prove such a statement?  assume countable (so there exists bijection f)  derive contradiction (some element not mapped to by f)  technique is called diagonalization (Cantor)