Hydra: Difference between revisions
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{{machine|1RB3RB---3LA1RA_2LA3RA4LB0LB0LA}} | {{machine|1RB3RB---3LA1RA_2LA3RA4LB0LB0LA}}{{unsolved|Does Hydra run forever?}}{{TM|1RB3RB---3LA1RA_2LA3RA4LB0LB0LA}} | ||
Hydra | Hydra is a [[BB(2,5)]] machine that simulates the Collatz-like iteration | ||
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== Name == | == Name == | ||
The name ''Hydra'' references the Ancient Greek legend: just as the legendary creature was growing 2 heads after losing 1 head, the | The name ''Hydra'' references the Ancient Greek legend: just as the legendary creature was growing 2 heads after losing 1 head, the ''b'' counter that is kept on the right side of the tape either increases by 2 or decreases by 1 (approximately with equal frequency if modelled as a random process; in reality it depends on the parity of ''a''). The Hydra dies (halts) when the last head is cut. | ||
==Sources== | ==Sources== | ||
Revision as of 01:57, 24 July 2024
Unsolved problem:
Does Hydra run forever?
1RB3RB---3LA1RA_2LA3RA4LB0LB0LA (bbch)
Hydra is a BB(2,5) machine that simulates the Collatz-like iteration
starting from .[1]
It is closely related to the machine Antihydra.[2]
A fast simulator for the odd/even sequence used by Hydra is available here.
Name
The name Hydra references the Ancient Greek legend: just as the legendary creature was growing 2 heads after losing 1 head, the b counter that is kept on the right side of the tape either increases by 2 or decreases by 1 (approximately with equal frequency if modelled as a random process; in reality it depends on the parity of a). The Hydra dies (halts) when the last head is cut.
Sources
- ↑ S. Ligocki, "BB(2, 5) is Hard (Hydra) (2023). Accessed 22 July 2024.
- ↑ S. Ligocki, "BB(6) is Hard (Antihydra)". Accessed 22 July 2024.