Set Theory · Countable Sets

Lesson 5

Nikolai Chukhin · Alexander S. Kulikov

Problem. Which of the following sets are countable?

5 points

  1. \(\mathbb{P}\), the set of primes.

  2. The set of all programs in your favorite programming language.

  3. The set \(\{i \cdot \sqrt{2}+j \cdot \sqrt{3}\colon i, j \in \mathbb{Z}\}\).