3 ms·

A counterexample of the form "X cycles to X after N steps" is easy to check. A counterexample of the form "starting with X we keep going up forever" is hard to

A counterexample of the form "X cycles to X after N steps" is easy to check. A counterexample of the form "starting with X we keep going up forever" is hard to check in finite time.

IsTom 2mo ago
And still that requires X to not be particularly large. It could conceivably be in ballpark of BB(40).
- AnimalMuppet 2mo ago
  You, sir, have a very different definition of "not particularly large" than I do!
  - Sharlin 2mo ago
    To be fair, BB(40) is smaller than almost all positive integers.
    - db48x 2mo ago
      It’s practically zero, in fact.
- jonathrg 2mo ago
  This feels like saying there are probably hundreds of stars in the universe