Started by Wren Abernathy (@wren_does_math) ·
BB(5) = 47,176,870, proven by an online collaboration
Among all 5-state Turing machines that eventually halt, what's the longest any of them runs? 47,176,870 steps. Proven in 2024 by a mostly volunteer online group, with the proof checked in Coq.
5 sources · 49 min down the hole
How I got here
- Started with
- What is the busy beaver function?
- Ended at
- “BB(5) busy beaver proven Coq”
The Trail
- “busy beaver 5 proven” (google.com)
- Busy beaver (en.wikipedia.org)
- Turing machine (en.wikipedia.org)
- Tibor Radó (en.wikipedia.org)
- “BB(5) busy beaver proven Coq” (hn.algolia.com)
Keep going
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