x66

x66
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 ]]
View animated image
View static image
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
Rules Outer-totalistic rules B3/S23 – B378/S2378 Important rules Conway Life # of rules 24 = 16 Isotropic rules B3-cy/S2-n3-ceky – B34ejkq5-ajk6-ai78/S234-ajkqw5-iqy6-a78
Glider synthesis Fewest gliders 12 Catagolue-generated RLE x66_synth.rle Uploaded synthesis RLE x66_synth.rle
Pattern files Plaintext x66.cells RLE x66.rle
Identifiers apgcode xq4_0oorxroozdjio404oijd Pentadecathlon ID 34P4H2V0.23 Eppstein ID 10240

x66 is a period-4 spaceship with speed c/2 orthogonal that was found by Hartmut Holzwart in July 1992.

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.

One of the symmetric halves can alternatively be escorted by a domino spark from the heavyweight spaceship, as shown below.

x = 9, y = 11, rule = B3/S23 2bo$2o$o2b3o2bo$o4b3o$b3o2b2o2$3b2o$bo4bo$o$o5bo$6o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ TRACKLOOP 4 -1/2 0 THUMBSIZE 2 GPS 4 ]]

HWSS on semi-x66 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

Glider synthesis

x66 was first synthesized by Martin Grant and Tanner Jacobi on January 11, 2015, requiring 162 gliders. After the emergence of this spaceship in a symmetrical soup found by Adam P. Goucher on March 8, 2015, this was drastically reduced to 13 gliders by Chris Cain, and then to 12 gliders in 2018. An alternative 12-glider synthesis with more stages was found by iNoMed on September 18, 2021.

A 9-glider synthesis for the HWSS on semi-x66 was found on March 8, 2015, from the same reaction used to create the full x66 in 13 gliders.

See also

• Blinker puffer 2

External links

• x66 at the Life Lexicon
• Life (B3/S23) at David Eppstein's Glider Database
• x66 at Adam P. Goucher's Catagolue
• 34P4H2V0.23 at Heinrich Koenig's Game of Life Object Catalogs