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2bo$2o$o2b3o2bo$o4b3o$b3o2b2o2$b3o2b2o$o4b3o$o2b3o2bo$2o$2bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ TRACKLOOP 4 -1/2 0 THUMBSIZE 2 GPS 4 ]]
Pattern type Spaceship
Number of cells 34
Bounding box 9×11
Direction Orthogonal
Period 4
Mod 4
Speed c/2
Speed (unsimplified) 2c/4
Heat 31
Discovered by Hartmut Holzwart
Year of discovery 1992

x66 is a period-4 spaceship with speed c/2 that was found by Hartmut Holzwart in July 1992. One of the symmetric halves can alternatively be escorted by a heavyweight spaceship. Its name refers to the fact that every cell (alive or dead) has at most 6 live neighbours (in contrast to spaceships based on lightweight spaceships, middleweight spaceships, or heavyweight spaceships). In fact, this spaceship was found via a search with this restriction. From this follows that the spaceship is stable also in Life-like rules allowing birth or survival for a cell with 7 or 8 neighbors.

x66 was first synthesized on January 11, 2015, requiring 162 gliders.[1] After the emergence of this spaceship in a symmetrical soup on March 8, 2015,[2] this was drastically reduced to 13 gliders,[3] and then to 12 gliders in 2018.[4]

Half of x66 can be supported by a heavyweight spaceship. A 9-glider synthesis for this variant was found on March 8, 2015, from the same reaction used to create the full x66 in 13 gliders.[5] Since the heavyweight spaceship is glide symmetric, it can support two halves at once, or one half alongside a sidecar.

Image gallery

Half of x66 supported by a heavyweight spaceship
RLE: here

See also


  1. Martin Grant (January 11, 2015). "Re: Small Spaceship Syntheses". Retrieved on March 18, 2019.
  2. flipper77 (March 8, 2015). "Re: Soup search results". Retrieved on March 18, 2016.
  3. Chris Cain (March 8, 2015). "Re: Soup search results". Retrieved on March 18, 2019.
  4. 2718281828 (January 15, 2018). "Re: Small Spaceship Syntheses". Retrieved on March 18, 2019.
  5. Matthias Merzenich (March 8, 2015). Re: Soup search results (discussion thread) at the ConwayLife.com forums

External links

  • 34P4H2V0.23 at Heinrich Koenig's Game of Life Object Catalogs