Blanking Busy Beaver Function: Difference between revisions

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== [[Instruction-Limited Busy Beaver|Instruction-limited]] Blanking Busy Beaver (BLBi(n)) ==
== [[Instruction-Limited Busy Beaver|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 to tape.
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 ===
=== Champions ===

Latest revision as of 12:58, 26 December 2025

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)
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 ?
BLBi(4) 12 ?
BLBi(5) 30 ?
BLBi(6) 77 1RB2LA0RB_1LA0LB1RA (bbch)
BLBi(7) 808 ?
BLBi(8) ≥ 1,367,361,263,049 1RB2RA1RA2RB_2LB3LA0RB0RA (bbch)

References

  1. Nick Drozd. "Blanking Beavers". Accessed 15 August 2025.
  2. 2.0 2.1 2.2 Nick Drozd. "Latest Beeping Busy Beaver Results". Accessed 15 August 2025.
  3. Comment #71 "https://scottaaronson.blog/?p=5661". Accessed 26 September 2025.
  4. Comment #62 "https://scottaaronson.blog/?p=5661". Accessed 26 September 2025.