New 10-state Turing machine sets BB(10) record, surpasses Graham's number
Researchers have identified a 10-state, 2-symbol Turing machine, dubbed n1, that halts on a blank tape and produces a number of 1s exceeding Graham's number. The machine's exact halting score and its placement at level ω+1 of the fast-growing hierarchy have been formally verified in Coq without relying on any axioms, surpassing the previous BB(10) champion, which sat at level ω.
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The result pushes the known frontier of the Busy Beaver problem for 10-state machines to a new growth-rate level, suggesting that small Turing machines can encode functions of extraordinary scale using relatively modest modifications to existing record-holding programs. Because the proof is machine-checked in Coq, it offers a high degree of confidence that could prompt renewed interest in exploring even larger or more complex small-state machines for future Busy Beaver research.
- A 10-state machine (n1) halts and generates a score proven to exceed Graham's number.
- The machine's score is formally verified in Coq to lie strictly between two values of f_(ω+1) in the fast-growing hierarchy.
- n1 builds on the BB(8) champion machine by adding two new states, surpassing the prior BB(10) record which was at level ω.
Source: github.com, 2026-10-13
Published there as: “BB(10) > Graham's Number”
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