set theory a first course cambridge mathematical
Uncountable Sets Countable sets: sets that can be put into a one-to-one correspondence with ℕ, e.g., ℕ, ℤ, ℚ Uncountable sets: larger than countable sets, e.g., the real numbers ℝ The Cantor Diagonal Argument This famous proof demonstrates that ℝ is uncountable, establishing the hierarchy of infini