In
Conway's Game of Life and
similar cellular automaton rules, a spark is a small collection of live cells that appears at the edge of some larger pattern such as a
spaceship or
oscillator
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...
, then quickly dies off.
Sparks are commonly separated by some distance from the main body of the pattern -- the analogy is to an object "throwing off sparks" -- but the minimum requirement is a set of cells on the pattern boundary that are alive in one phase but dead in a later phase, and that are unaffected by other parts of the pattern (they would die in the same way if the rest of the pattern were removed). The converse is not necessarily true: for example, removing the spark in the accompanying illustration would destabilize the
fumarole. (Many spark-producing oscillators have this property.)
Sparks are an important way for components of a larger pattern to interact with each other; for instance, Niemiec describes the use of sparks formed by colliding
gliders as part of the synthesis of other life objects. Bell
["Spaceships in Conway's Life", David I. Bell, available fro]
Bell's home page
writes that lightweight, mediumweight, and heavyweight spaceships in Life are especially useful because they all have small sparks which may be used to perturb nearby
puffer trains and stationary patterns as the spaceships pass by them.
References
External links
Stephen Silver's Life Lexiconhome page
from Eric Weisstein's Treasure Trove of Life C.A.
{{Conway's Game of Life
Cellular automaton patterns