Mathematics For Computer Science - Finite and Infinite Sets

​Finite and infinite sets
A finite set is one with a finite number of elements. For example, {1, 2, 7, 10} is a finite
set as it has four elements. An infinite set is one that has an infinite number of elements
such as ℝ, the set of real numbers. It is impossible to count how many real numbers
there are.
A countably infinite set is one that can be counted off by the natural numbers. Rational
numbers are countably infinite in this way. However, German mathematician Georg
Cantor proved that real numbers are not countable.