Pure glider generator

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A pure glider generator (or simply glider generator) is a pattern that evolves into one or more gliders and nothing else.[1][2] They are part of the cosmological classification of Life patterns. There was interest in this scheme early on, and within it on pure glider generators in particular (they were reported on quite frequently in the early issues of Lifeline, for example).

However, there are so many easy-to-find pure glider generators that it's impossible to catalogue them all, unless some extra constraints are added (for example being easily glider-constructible, or being made out of just blocks, or being a one-cell-thick pattern).[3][4][5]

Examples

x = 12, y = 9, rule = B3/S23 4b4o2$2b8o2$12o2$2b8o2$4b4o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 500 THUMBSIZE 2 GPS 5 AUTOSTART T 0 PAUSE 2 LOOP 30 ]]
The 4-8-12 diamond
(click above to open LifeViewer)
RLE: here Plaintext: here
x = 4, y = 7, rule = B3/S23 2bo$bobo$o2bo$b2o$o2bo$obo$bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 500 THUMBSIZE 2 GPS 5 AUTOSTART T 0 PAUSE 2 LOOP 30 ]]
The bi-loaf
(click above to open LifeViewer)
RLE: here Plaintext: here
x = 7, y = 7, rule = B3/S23 2bo$2o$2b2o$bo3bo$3b2o$5b2o$4bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 500 THUMBSIZE 2 GPS 5 AUTOSTART T 0 PAUSE 2 LOOP 30 ]]
The bi-clock
(click above to open LifeViewer)
RLE: here Plaintext: here


The 4-8-12 diamond and the bi-loaf[note 1] are two pure glider generators found by the Honeywell group in 1971.[6] The former evolves into four gliders (one heading in each diagonal direction) in 15 generations, while the latter yields two after four ticks. Gliders from the bi-loaf run in opposite ways along the diagonal that is closest to the great axis of the pattern. E.g. when the great axis is NNE-SSW, the gliders' directions are northeast & southwest. The bi-clock is a later example found by Dale Edwin Cole in the same year.[7] It consists of two closely placed clocks, and evolves into two gliders in two generations.

x = 6, y = 2, rule = B3/S23 6o$5o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 500 THUMBSIZE 2 GPS 5 AUTOSTART T 0 PAUSE 2 LOOP 30 ]]
An undecomino that evolves into a single glider
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RLE: here Plaintext: here
x = 15, y=9, rule = B3/S23 2bo$2bo$3o2$6b3o$7bo$12b3o$12bo$12bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 500 THUMBSIZE 2 GPS 5 AUTOSTART T 0 PAUSE 2 LOOP 40 ]]
Evolves into four gliders, one travelling in each direction
(click above to open LifeViewer)
RLE: here Plaintext: here


A pure glider generator was featured on Randall Munroe's webcomic xkcd as a tribute to John Conway, the inventor of Game of Life.[8]

See also

Notes

  1. ↑ The term "bi-loaf" is now a collective description of the still lifes consisting of two loaves, e.g. the half-bakery and the loaf back tie loaf.

References

  1. ↑ Pure glider generator at the Life Lexicon
  2. ↑ twinb7 (March 2nd, 2014). Pure Glider Generators (discussion thread) at the ConwayLife.com forums
  3. ↑ Dave Greene (March 8th, 2014). Re: Pure Glider Generators (discussion thread) at the ConwayLife.com forums
  4. ↑ knightlife (April 4th, 2013). Blockic splitters (discussion thread) at the ConwayLife.com forums
  5. ↑ twinb7 (March 5th, 2014). 1-Dimensional Patterns (discussion thread) at the ConwayLife.com forums
  6. ↑ Robert Wainwright (March 1971). Lifeline, vol 1, page 3.
  7. ↑ Robert Wainwright (June 1971). Lifeline, vol 2, page 5.
  8. ↑ Randall Munroe (April 13, 2020). "2293: RIP John Conway". Retrieved on December 18, 2020.

External links


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