Holdouts lists: Difference between revisions
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(Added an entry for the current BB(6) holdout spreadsheet.) |
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|[https://docs.google.com/spreadsheets/d/1grhW_0neb2I8TfceN5-v70_3W42Z2U159r9L6FhPGf8/edit?usp=sharing Spreadsheet of holdouts] | |[https://docs.google.com/spreadsheets/d/1grhW_0neb2I8TfceN5-v70_3W42Z2U159r9L6FhPGf8/edit?usp=sharing Spreadsheet of holdouts] | ||
|Keeping track of BB(6) progress. | |Keeping track of BB(6) progress - informal. | ||
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|[[BB(3,3)]] | |[[BB(3,3)]] | ||
Revision as of 23:28, 27 November 2024
A holdout (or undecided machine) is a Turing machine for which it is not known whether the machine halts or not from all-0 input tape. Holdouts are the machines which deciders are unable to decide.
Holdout lists are often shared by contributors. Here is a table that summarises the number of holdout per busy beaver domain:
| 2-state | 3-state | 4-state | 5-state | 6-state | |
|---|---|---|---|---|---|
| 2-symbol | 0 | 0 | 0 | 0 | 4408 |
| 3-symbol | 0 | 6 | |||
| 4-symbol | 0 | 434,787,751 | |||
| 5-symbol | 273 | ||||
| 6-symbol | 22,302,296 |
Downloadable lists
Georgi Georgiev (Skelet) posted a list of 43 holdouts for BB(5) in 2003. bbchallenge.org successfully reduced the number of holdouts for BB(5) to zero in June 2024.