Caterloopillar

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Caterloopillar
Caterloopillar image
Pattern type Spaceship
Family Caterloopillar
Number of cells 232815
Bounding box 734×514927
Direction Orthogonal
Period 2000
Mod Unknown
Speed c/8
Speed (unsimplified) 250c/2000
Heat 220775.0
Discovered by Michael Simkin
Year of discovery 2016

Caterloopillar is the name given to a family of spaceships which provides a general solution for self-supporting orthogonal travel at a wide range of speeds.

The design is made up of two major parts, the front and the back. In Caterloopillar, each of these parts is a universal constructor that constructs the building blocks of the other part, while also reading and moving a construction tape. As the name suggests, this creates somewhat paradoxical design, similar to the "strange loop" concept.

The Caterloopillar was voted the Pattern of the Year 2016 on ConwayLife.com.[1]

A Golly script is available that can generate spaceships of all supported speeds and lower than c/4. The script does not work for one special subset of speeds which requires a somewhat more research. In other words, there is a subspace which is still not solved technically, but there are no theoretical difficulties in the way of finding the necessary additional recipes and updating the script to handle them.

History

The general idea of adjustable speed spaceships was proposed by David Bell in October 2006 on the LifeCA mailing list[2], and possibly earlier and independently by Jason Summers. Hartmut Holzwart revived discussion about the idea in September 2014 on the ConwayLife.com forums.[3]

During those discussions, Alexey Nigin in 2014 proposed a novel way of construction that would avoid helices. Instead it would use two streams upward and downward, that create each other using slow salvos.[4] Surprisingly enough the final design[5] of the first Caterloopillar was very close to his description.

Alexey Nigin's initial design proposal was purely theoretical. The first example showing that the idea could be efficiently implemented was found by Michael Simkin a few days after the initial suggestion[6].

The name was also extensively discussed, with suggestions including strange loop,[7] strange-caterloopillar,[8] pushmi-pullyou[9] and caterloop,[10] finally arriving at Caterloopillar in June 2015.[11]

Implementation

The first Caterloopillar was constructed by Michael Simkin and completed on April 9, 2016; this Caterloopillar has a speed of c/8. Caterloopillars with many other speeds can be constructed using a slightly modified design. The major limitation of this implementation is upper bound of speed c/4, as the signal transferring is done by converting a still life into a glider and back, thus limiting the moving speed of the tape to c/4 (the speed of the glider).

Caterloopillars of various other speeds (see list of spaceships for a full list) were later constructed using the script,[12][13][14][15][16] the first three being c/9, c/11 and c/12 orthogonal, respectively. One of the most notable Caterloopillars is a 31c/240 one smaller than the Centipede, a previous record holder for that speed which was not based on Caterloopillar technology. It has since been surpassed by the current record holder, the silverfish.

In general, faster Caterloopillars appear to require more cells.

See also

References

  1. Alexey Nigin (June 3, 2017). Pattern of the Year 2016 (Results) (discussion thread) at the ConwayLife.com forums
  2. David Bell (October 8, 2006). "Idea for various speed Caterpillars based on standard spaceships". Retrieved on April 11, 2016.
  3. Hartmut Holzwart (September 11, 2014). David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  4. Alexey Nigin (November 12th, 2014). "A novel way of construction".
  5. Michael Simkin (April 9, 2016). "Caterloopillar WIP (all speeds < c/4)". Retrieved on February 16, 2018.
  6. Michael Simkin (November 14th, 2014). "Caterloopillar first reading head examples".
  7. Ivan Fomichev (November 15, 2014). Re: David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  8. Dave Greene (June 19, 2015). Re: David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  9. Ivan Fomichev (November 22, 2014). Re: David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  10. Michael Simkin (November 15, 2014). Re: David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  11. Michael Simkin (June 20, 2015). Re: David Bell's engineless caterpillar idea revisited (discussion thread) at the ConwayLife.com forums
  12. Michael Simkin (April 15, 2016). Re: Caterloopillar WIP (all speeds < c/4) (discussion thread) at the ConwayLife.com forums
  13. Michael Simkin (April 15, 2016). Re: Caterloopillar WIP (all speeds < c/4) (discussion thread) at the ConwayLife.com forums
  14. Michael Simkin (April 16, 2016). Re: Caterloopillar WIP (all speeds < c/4) (discussion thread) at the ConwayLife.com forums
  15. thunk (April 16, 2016). Re: Caterloopillar WIP (all speeds < c/4) (discussion thread) at the ConwayLife.com forums
  16. Michael Simkin (April 17, 2016). Re: Caterloopillar WIP (all speeds < c/4) (discussion thread) at the ConwayLife.com forums

External links