Block on cap

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Block on cap
x = 4, y = 6, rule = B3/S23 b2o$o2bo$4o2$2o$2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 ZOOM 21 HEIGHT 400 SUPPRESS ]] [[ ZOOM 48 ]]
Pattern type Strict still life
Number of cells 12
Bounding box 6 × 4
Frequency class 19.3
Discovered by Robert Wainwright
Everett Boyer
Year of discovery 1973

Block on cap is a 12-cell still life composed of a cap being stabilized by a block.


x = 81, y = 36, rule = B3/S23 8b2o$7bo2bo$7b4o2$7b2o$7b2o8$obo27bobo27bobo$b2o15bo12b2o15bo12b2o15bo $bo16bobo10bo16bobo10bo16bobo$18b2o28b2o28b2o6$14bobo$14b2o$15bo5$31b 2o39b2o$32b2o37b2o$31bo7bo25bo7bo$38b2o25b2o$2o36bobo23bobo$b2o$o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THEME Book ZOOM 6 AUTOSTART GPS 12 T 0 PAUSE 3 T 32 PAUSE 2 LOOP 33 ]]
4G syntheses[1][2]
(click above to open LifeViewer)

The block on cap can be constructed with 4 gliders. A number of known alternate syntheses can be found in Mark Niemiec's database.[2]


Main article: List of common still lifes

Block on cap is the forty-eighth most common still life in Achim Flammenkamp's census, being less common than elevener but more common than trans-loaf with tail.[3]

It is the 49th most common still life on Adam P. Goucher's Catagolue, being less common than mirrored dock but more common than trans-loaf with tail. It is the 3rd most common still life with 12 cells, being less common than mirrored table but more common than trans-block on long bookend.[4]

There are 3 collisions in the octohash database[5] and 35 collisions in the octo3obj database where the final pattern contains a block on cap along with other junk.

See also


  1. 2, 3, and 4-glider syntheses at Dean Hickerson's Life page
  2. 2.0 2.1 The 121 twelve-bit still-lifes at Mark D. Niemiec's Life Page (download pattern file: 12/12-27.rle)
  3. Achim Flammenkamp (September 7, 2004). "Most seen natural occurring ash objects in Game of Life". Retrieved on January 15, 2009.
  4. Adam P. Goucher. "Statistics". Catagolue. Retrieved on May 5, 2023.
  5. Two out of three collisions converge to the same sequence after 9 ticks; the headerless RLEs are b2o$obo$bo3$2b2o$bo2bo2b2o$2bobob2o$3bo4bo! and b2o$obo$bo3$3bo$2bobo2b2o$bo2bob2o$2b2o4bo! Third collision is 8b2o$7bobo$7b2o6$b2o$o2bo$o2bo$b2o2b2o$5bobo$5bo!

External links