TMBR: July 2026: Difference between revisions

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TODO: Post Tag System
TODO: Post Tag System


TODO: Wang tiles (https://discord.com/channels/960643023006490684/1529586687926210691)
* [[Wang Tiles]]
** Over July 22-25, AlephSquirrel found champions 1-4 and proved their optimality, and found the BB_WT(5) champion.
** Prior work by Emmanuel Jeandel and Michael Rao in 2015 shows BB_WT(10) ≥ 212.<ref>https://arxiv.org/abs/1506.06492</ref>


== Holdouts ==
== Holdouts ==

Revision as of 15:44, 3 October 2026

Prev: June 2026 This Month in Beaver Research Next: August 2026

This edition of TMBR is in progress and has not yet been released. Please add any notes you think may be relevant (including in the form a of a TODO with a link to any relevant Discord discussion).

General

BB Adjacent

SKI Calculus:

  • A new champion was discovered for Ξ₀(12).
  • New champions were discovered for Ξ₀SK(12), Ξ₀SK(13), Ξ₀S(14), Ξ₀SK(15), Ξ₀SK(16) and Ξ₀SK(17).

TODO: update

Lambda Calculus:

  • BBλ(40) was solved on 20 July, showing that BBλ(40) ≈ 10↑↑↑16. BBλ(40) is the first solved domain in any BB variant to reach pentational values.

TODO: Post Tag System

  • Wang Tiles
    • Over July 22-25, AlephSquirrel found champions 1-4 and proved their optimality, and found the BB_WT(5) champion.
    • Prior work by Emmanuel Jeandel and Michael Rao in 2015 shows BB_WT(10) ≥ 212.[1]

Holdouts

BB Holdout Reduction by Domain
Domain Previous Holdout Count New Holdout Count Holdout Reduction % Reduction
BB(6) 1,094 1,064 30 2.74%
BB(4,3) 4,784,443 4,747,566 36,877 0.77%
  • BB(6)
    • On 2 July, mxdys solved three holdouts in rocq.[1][2]
    • On 3 July, mxdys solved another holdout in rocq using an LLM.
    • mxdys released a new holdouts list of 1,064 machines up to equivalence, this is a 2.74% reduction compared to the previous holdouts list.
    • On 28 July, prurq found a TM to halt. This was verified by mxdys in rocq two days later together with another machine.
    • TODO: BMO 9 and BMO 10
  • BB(4,3)
    • Andrew Ducharme reduced the number of holdouts from 4,784,443 to 4,747,566, a 0.77% reduction.[3][4]
  • BB(2,7)
    • Terry Ligocki enumerated 180K more subtasks, increasing the number of holdouts to 2,185,010,519. A total of 700K subtasks out of the 1 million subtasks (or 70%) have been enumerated.