[Decider] Unilateral Bouncers

Congrats on your work, reading your code was a pleasure as it is really clear.

I am now convinced that your decider does indeed recognise unilateral bouncers and am also confident that a formal of correctness is within reach.

I propose that we vote on whether your decider should officially be applied on bbchallenge now. Let’s give this vote 2 full weeks, starting now.

Here are my pros and cons:


  1. The technique is elegant and yields a compact and concise code, amenable to being formally proved correct (@Iijil gave a draft of the proof).
  2. The technique seems to allow to decide all unilateral bouncers. (I still personally need to do a bit of work on my side to get 100% convinced but I trust @Iijil confidence on the matter).


  1. A decider for bilateral bouncers will probably also recognise unilateral bouncers.
  2. Unilateral bouncers seem to “only” correspond to ~15% of the currently 1.5M undecided machines. This poses the question of whether even simpler techniques that this one could end up deciding more machines (such as your [Decider] Halting Segment).

My personal vote is in favor of applying the decider: deciding 15% of the currently undecided machines is still a significant contribution and the technique can be proved correct without too many efforts (it seems). I also like the fact that the decider seems to exactly recognise the class of unilateral bouncers. Finally, I would like to acknowledge the significant effort realised by @Iijil to put this decider outhere while achieving all the standards that we care for the code of deciders. Thank you!