Incellular automata such asConway's Game of Life, abreeder is a pattern that exhibitsquadratic growth, by generating multiple copies of a secondary pattern, each of which then generates multiple copies of a tertiary pattern.[1]
Breeders can be classed by the relative motion of the patterns. The classes are denoted by three-letter codes, which denote whether the primary, secondary and tertiary elements respectively are moving (M) or stationary (S). The four basic types are:[1]
Aspacefiller (which also undergoes quadratic growth) may be thought of as a fifth class of breeder. However it differs from a true breeder in that it expands a single island of cells, rather than creating independent objects. It is known that a fifth class breeder cannot be locked in place.