Cycler: Difference between revisions

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[[File:1RB0LB 1LB1LC 0RC1RA.png|alt=1RB0LB_1LB1LC_0RC1RA|thumb|upright=1.5|The record 3-state 2-symbol cycler {{TM|1RB0LB_1LB1LC_0RC1RA}}, which has period 18 and preperiod 4.]]
[[File:1RB0LB 1LB1LC 0RC1RA.png|alt=1RB0LB_1LB1LC_0RC1RA|thumb|upright=1.5|The record 3-state 2-symbol cycler {{TM|1RB0LB_1LB1LC_0RC1RA}}, which has period 18 and preperiod 4.]]{{Stub}}
A '''cycler''' is a Turing machine that eventually enters a repeating cycle. Such a Turing machine runs forever, so is a [[non-halting Turing machine]]. A cycler may be seen as a special case of a [[translated cycler]] which has offset zero.
A '''cycler''' is a Turing machine that eventually enters a repeating cycle. Such a Turing machine runs forever and thus is a [[non-halting Turing machine]]. A cycler may be seen as a special case of a [[translated cycler]] which has offset zero.


The rule for identifying cyclers is simple:
The rule for identifying cyclers is simple:
  '''û''' → '''û'''
  '''û''' → '''û'''
where '''û''' is any headed tape segment.
where '''û''' is any headed tape segment.
==Related Functions==
* Busy Preperiodic Beaver ([[BBS]](n,m)): The longest possible preperiod of a cycler or translated cycler with n states and m symbols.
* Busy Periodic Beaver ([[BBP]](n,m)): The longest possible period of a cycler or translated cycler with n states and m symbols.


== See also ==
== See also ==


* [[Translated cycler]]
* [[Translated cycler]]
* [https://github.com/bbchallenge/bbchallenge-proofs/blob/build-latex-pdf/deciders/correctness-deciders.pdf Section 2] of bbchallenge's deciders write-up.


[[Category:Zoology]]
[[Category:Zoology]]
[[Category:Stub]]

Latest revision as of 11:01, 17 August 2025

1RB0LB_1LB1LC_0RC1RA
The record 3-state 2-symbol cycler 1RB0LB_1LB1LC_0RC1RA (bbch), which has period 18 and preperiod 4.

A cycler is a Turing machine that eventually enters a repeating cycle. Such a Turing machine runs forever and thus is a non-halting Turing machine. A cycler may be seen as a special case of a translated cycler which has offset zero.

The rule for identifying cyclers is simple:

ûû

where û is any headed tape segment.

Related Functions

  • Busy Preperiodic Beaver (BBS(n,m)): The longest possible preperiod of a cycler or translated cycler with n states and m symbols.
  • Busy Periodic Beaver (BBP(n,m)): The longest possible period of a cycler or translated cycler with n states and m symbols.

See also