This is a haskell project that contains the main computations for a proof that the longest arithmetic progression that is a subset of a geometric progression $(\xi^i)_{i \in \mathbb{N}}, \xi \in \mathbb{C}$ is only $3$, unless $\xi = 0$ or $\xi^m = 1$ for some $m \in \mathbb{N}$.

A more detailed explanation can be found here