5-state busy beaver winner: Difference between revisions

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== Behavior ==
== Behavior ==
This machine repeatedly applies the following map, starting with <math>x = 0</math><ref>Aaronson, S. (2020). The Busy Beaver Frontier. Page 10-11. https://www.scottaaronson.com/papers/bb.pdf</ref>:
This machine repeatedly applies the following [[Collatz-like]] map, starting with <math>x = 0</math><ref>Aaronson, S. (2020). The Busy Beaver Frontier. Page 10-11. https://www.scottaaronson.com/papers/bb.pdf</ref>:
<math display="block">\begin{align}
<math display="block">\begin{align}
   g(x) & \to \frac{5x+18}{3} && \text{if }x \equiv 0 \pmod{3} \\
   g(x) & \to \frac{5x+18}{3} && \text{if }x \equiv 0 \pmod{3} \\

Revision as of 15:36, 10 September 2024

The 5-state busy beaver (BB(5)) champion (and winner!) is: 1RB1LC_1RC1RB_1RD0LE_1LA1LD_1RZ0LA (bbch). It was found by Heiner Marxen and Jürgen Buntrock in 1989[1]. The machine halts after 47,176,870 steps and with 4098 1's on the tape, showing that BB(5)47,176,870 and Σ(5)4098.

Behavior

This machine repeatedly applies the following Collatz-like map, starting with x=0[2]: g(x)5x+183if x0(mod3)g(x)5x+223if x1(mod3)g(x)HALTif x2(mod3)which can alternatively be written as[3]:

g(3k)5k+6g(3k+1)5k+9g(3k+2)HALT

The full orbit from x=0 is: 06163464114196334564946158426464416736612284HALT

References

  1. H. Marxen and J. Buntrock. Attacking the Busy Beaver 5. Bulletin of the EATCS, 40, pages 247-251, February 1990. https://turbotm.de/~heiner/BB/mabu90.html
  2. Aaronson, S. (2020). The Busy Beaver Frontier. Page 10-11. https://www.scottaaronson.com/papers/bb.pdf
  3. Pascal Michel. Behavior of busy beavers.https://bbchallenge.org/~pascal.michel/beh#tm52a