User:Azerty/Busy Beaver Functions
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This is a list of Busy Beaver functions for Turing machines and other simple Turing-complete systems and their current lower bounds.
All functions here grow uncomputably fast like the original Busy Beaver function. There is no function that grow much faster like the Beeping Busy Beaver function here.
I will add more functions soon.
Turing Machines
| Function | Lower Bound | Champion |
|---|---|---|
| BB(2) | 6 | 1RB1LB_1LA1RZ (bbch)
|
| BB(3) | 21 | 1RB1RZ_1LB0RC_1LC1LA (bbch)
|
| BB(2,3) | 38 | 1RB2LB1RZ_2LA2RB1LB (bbch)
|
| BB(4) | 107 | 1RB1LB_1LA0LC_1RZ1LD_1RD0RA (bbch)
|
| BB(2,4) | 3,932,964 | 1RB2LA1RA1RA_1LB1LA3RB1RZ (bbch)
|
| BB(5) | 47,176,870 | 1RB1LC_1RC1RB_1RD0LE_1LA1LD_1RZ0LA (bbch)
|
| BB(3,3) | 0RB2LA1RA_1LA2RB1RC_1RZ1LB1LC (bbch)
| |
| BB(2,5) | 1RB3LA4RB0RB2LA_1LB2LA3LA1RA1RZ (bbch)
| |
| BB(2,6) | [1] | 1RB3RB5RA1LB5LA2LB_2LA2RA4RB1RZ3LB2LA (bbch)
|
| BB(6) | [1] | 1RB1RA_1RC1RZ_1LD0RF_1RA0LE_0LD1RC_1RA0RE (bbch)
|
| BB(4,3) | 1RB1RD1LC_2LB1RB1LC_1RZ1LA1LD_0RB2RA2RD (bbch)
| |
| BB(7) | 1RB0RA_1LC1LF_1RD0LB_1RA1LE_1RZ0LC_1RG1LD_0RG0RF (bbch)
| |
| BB(3,4) | [2] | 1RB3LB1RZ2RA_2LC3RB1LC2RA_3RB1LB3LC2RC (bbch)
|
- ↑ 1.0 1.1 S. Ligocki, "BB(2,6) > 10↑↑10↑↑10↑↑3". Blog post, 2023. Accessed 15 August 2025.
- ↑ S. Ligocki. "BB(3,4) > Ack(14)." https://www.sligocki.com/2024/05/22/bb-3-4-a14.html Blog post, 2024. Accessed 15 August 2025.