Figure eight

Figure eight
2o$2obo$4bo$bo$2bob2o$4b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ GPS 4 THUMBSIZE 2 ]]
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Pattern type	Oscillator
Number of cells	12
Bounding box	10×10
Frequency class	23.4
Period	8
Mod	8
Heat	16.5
Volatility	1.00
Strict volatility	1.00
Discovered by	Simon Norton
Year of discovery	1970
Rules Outer-totalistic rules B3/S23 – B378/S237 Important rules Conway Life # of rules 23 = 8 Isotropic rules B3-jky/S2-e3acinq – B2ci34cikqtyz5-k6-n78/S234-jknqr5-aci6-e7
Glider synthesis Fewest gliders 4 Catagolue-generated RLE figureeight_synth.rle Uploaded synthesis RLE figureeight_synth.rle
Pattern files Plaintext figureeight.cells RLE figureeight.rle
Identifiers apgcode xp8_gk2gb3z11 Pentadecathlon ID 12P8.1

Figure eight (or less frequently, big beacon or lemniscate) is a period-8 oscillator found by Simon Norton in 1970. With 12 cells in its initial phase, it is the smallest known period 8 oscillator, behind blocker at 15 cells. It is known that no period 8 oscillators exist with 10 or fewer cells.

As a building block for larger oscillators

Because it produces a domino spark in one of its phases, it is useful for constructing larger oscillators that have period that is a multiple of eight. For example, it appears in tumbling T-tetson (period 8), sailboat (period 16), caterer on figure eight (the smallest period 24 oscillator), and figure eight on 36P22 (period 88).

As a reflector

Figure eight has the ability to act as a 90-degree glider reflector when it is combined with a block, boat and eater 1. The input path (in green) and output path (in red) of the glider are shown below.

Figure eight acting as a reflector
RLE: here

Commonness

Figure eight is the tenth most common naturally-occurring oscillator in Achim Flammenkamp's census, being less common than the great on-off but more common than the spark coil. On Catagolue, it is the most common period 8 oscillator, being more common than blocker.

Image gallery

• 

  One of the phases of the oscillator, which led to both of its names.

See also

• Kok's galaxy

External links

• Figure-8 at the Life Lexicon

• Figure-8 at Adam P. Goucher's Catagolue

• 12P8.1 at Heinrich Koenig's Game of Life Object Catalogs