The current BB(6) record holder machine was found by Pavel Kropitz in 2022. It runs for ≃10↑↑15 steps before halting.

Is that the BB(6) machine?

This question resolves YES if that machine is proven to be the BB(6) machine. All other machines must be proven non-halting or to halt in fewer steps. This question resolves NO if a different machine is found to halt after more steps. If this machine achieves the BB(6) bound, but not uniquely, this question resolves YES. The due date will be extended as needed. This question will use the shifts function S(n) in the event that the champion for the shifts function and the ones function Σ(n) are distinct.

See also:

• BB(6) holdouts

• Records and analysis

The machine specification:

1RB0LD_1RC0RF_1LC1LA_0LE1RZ_1LF0RB_0RC0RE

• Update 2025-06-29 (PST) (AI summary of creator comment): A new machine has been found and proven to halt after running for more steps than the Kropitz 2022 machine. According to the market criteria, this is a condition for a NO resolution.