Kickback

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x = 7, y = 12, rule = B3/S23 5bo$4bo$4b3o7$b2o$obo$2bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 3 WIDTH 560 HEIGHT 240 PAUSE 2 AUTOSTART GPS 10 LOOP 50 ]]
The 180-degree kickback[1]
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x = 7, y = 12, rule = B3/S23 5bo$4bo$4b3o7$bo$2o$obo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 3 WIDTH 560 HEIGHT 240 PAUSE 2 AUTOSTART GPS 10 LOOP 50 ]]
The 90-degree kickback[2]
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A kickback is any of the two 2-glider collisions resulting in a single glider travelling in the opposite direction to one of the original gliders. In a 90-degree kickback, the two gliders collide at right angle, while in a 180-degree kickback they are head-on. Both output gliders are one half-diagonal away from the lane of one of the inputs.

The 90-degree kickback is important in the original proof of the existence of a universal constructor (using an elbow ladder) and in Bill Gosper's total aperiodic, as well as a number of other constructions and glider syntheses. Thus the term kickback reaction may also refer to the 90-degree one specifically. The 180-degree kickback is rarely used in signal circuitry or in self-supporting patterns like the Caterpillar or Centipede, because it is generally less easy to arrange.

References

  1. Robert Wainwright (March 1971). "Lifeline Volume 1". Lifeline page 4.
  2. Robert Wainwright (September 1973). "Lifeline Volume 11". Lifeline page 10.

External links