One of my favorite facts about FRACTRAN that's often missing from articles around it [0] > And it follows that FRACTRAN games are undecidable. This doesn’t spe

One of my favorite facts about FRACTRAN that's often missing from articles around it [0] > And it follows that FRACTRAN games are undecidable. This doesn’t speak directly to the Collatz conjecture, because (1/2)n | 3n + 1 is not a FRACTRAN game. But it does follow that arbitrary Collatz games are undecidable, since the set of all Collatz games includes the set of all FRACTRAN games. [0] https://raganwald.com/2020/05/03/fractran.html#why-fractran-really-matters https://raganwald.com/2020/05/03/fractran.html#why-fractran-...