Blanking Busy Beaver Function: Difference between revisions
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Latest revision as of 21:20, 4 January 2026
The Blanking Busy Beaver Function (BLB(n,m)) is a Busy Beaver Function which measures the largest amount of steps done by any Turing machine with n states and m symbols before blanking the tape. Blanking Busy Beaver machines are allowed to be halting or non-halting. As machines with just a single state cannot blank the tape, BLB(1,m) is nonexistent for any amount of symbols m. Similarly, BLB(n,1) is nonexistent for any amount of states n, as the tape of 1-symbol machines is always blank.
Champions
| 2 Symbols: | Steps | Champions |
|---|---|---|
| BLB(2) | 8[1] | 1RB0RA_1LB1LA (bbch)
|
| BLB(3) | ≥ 34[2] | 1RB1LB_1LA1LC_1RC0LC (bbch)
|
| BLB(4) | ≥ 32,779,477 | 1RB1LD_1RC1RB_1LC1LA_0RC0RD (bbch)
|
| BLB(5) | ≥ 32,810,047[3] | 1RB1LC_1RD0LE_0RD0RC_1LD1LA_1RB1RE (bbch)
|
| BLB(6) | ≥ 65,538,549[4] | 1RB1LE_1RD1RB_0RD0RE_1LD1LA_0RF1RF_0LC1LC (bbch)
|
| 3 Symbols: | Steps | Champions |
|---|---|---|
| BLB(2,3) | ≥ 77[2] | 1RB2LA0RB_1LA0LB1RA (bbch)
|
| BLB(3,3) | ≥ 329 | 1RB2LC2LA_1LC---2RA_2RC2LB0LC (bbch)
|
| 4 Symbols: | Steps | Champions |
|---|---|---|
| BLB(2,4) | ≥ 1,367,361,263,049[2] | 1RB2RA1RA2RB_2LB3LA0RB0RA (bbch)
|
Instruction-limited Blanking Busy Beaver (BLBi(n))
BLBi(n) is the largest amount of steps taken by an n-instruction Turing machine when blanking the tape for the first time after having written a non-blank symbol on the tape.
Champions
Note that BLBi(1) and BLBi(2) are nonexistent as Turing machines with one or two instructions cannot blank the tape.
| Instructions | Steps | Champions |
|---|---|---|
| BLBi(3) | 4 | 1RB0RA_1LA--- (bbch)
|
| BLBi(4) | 12 | 1RB---_1RC---_1LC0RC (bbch)
|
| BLBi(5) | 30 | 1RB------_1RC------_2LC2RC0RC (bbch)
|
| BLBi(6) | 77 | 1RB2LA0RB_1LA0LB1RA (bbch)
|
| BLBi(7) | 808 | 1RB------_1RC------_0RD2LC---_1LD2RD0RC (bbch)
|
| BLBi(8) | ≥ 1,367,361,263,049 | 1RB2RA1RA2RB_2LB3LA0RB0RA (bbch)
|
References
- ↑ Nick Drozd. "Blanking Beavers". Accessed 15 August 2025.
- ↑ 2.0 2.1 2.2 Nick Drozd. "Latest Beeping Busy Beaver Results". Accessed 15 August 2025.
- ↑ Comment #71 "https://scottaaronson.blog/?p=5661". Accessed 26 September 2025.
- ↑ Comment #62 "https://scottaaronson.blog/?p=5661". Accessed 26 September 2025.