Dead spark coil

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Dead spark coil
x = 7, y = 5, rule = B3/S23 2o3b2o$obobobo$2bobo$obobobo$2o3b2o! #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 18
Bounding box 7 × 5
Frequency class 16.3
Discovered by Unknown
Year of discovery Unknown

Dead spark coil is an 18-cell strict still life consisting of two mutually stabilising houses. It is one of three ways in which two houses can be arranged to create a still life, and one of the two which have two separate islands.

Skewing the two constituent houses gives rotated house, whereas connecting them diagonally to stabilise each other gives house bridge house.

One half of the dead spark coils can eat gliders, but both the top and bottom of that side must have a glider to eat at the same time, or else the other side of the house will interfere.


Main article: List of common still lifes

Dead spark coil is the forty-fifth most common still life in Achim Flammenkamp's census, being less common than trans-mirrored bun but more common than cis-mirrored bookend.[1]

It is the 31st most common still life on Adam P. Goucher's Catagolue, being less common than mirrored table but more common than canoe. It is the most common still life with 18 cells, being 26 times as common as cis-mirrored dove.[2]

Dead spark coils are typically formed when two pi-heptominoes face each other three cells apart. If they are four cells apart, they instead form a live spark coil.

In D2_+1 symmetry, it is the 12th most common still life, being about 100 times more common than in an asymmetric soup, and it is the most common still life that takes advantage of symmetry to be much more common.

Glider synthesis

Dead spark coil can be very simply synthesised in four gliders via two colliding pi-heptominoes, which take two gliders each.

In other rules

In HighLife, dead spark coil is an oscillator in much the same way as spark coil is, with a single-cell on-off rotor. Such a single-cell rotor is impossible in Life (B3/S23) since birth conditions are a subset of the survival conditions, so any rotor cell must be adjacent to another rotor cell.

See also


  1. Achim Flammenkamp (September 7, 2004). "Most seen natural occurring ash objects in Game of Life". Retrieved on January 15, 2009.
  2. Adam P. Goucher. "Statistics". Catagolue. Retrieved on May 5, 2023.

External links