1. Define Liouville numbers
2. Show that in the definition of Liouville numbers taken from Wikipedia the quantification of n can be replaced from "every positive integer" into "non-zero natural number".
3. Prove auxiliary lemma that powers of two are unbounded, i.e., for any integer d, there exists a non-zero natural number such that 2 to_power (n - 1) > d.
4. Prove that no Liouville number can be rational (follow the proof from Wikipedia).

Exercises with skeletons of proofs (should be in text directory)

Complete formalization