A breeder is any pattern that exhibits unbounded quadratic growth. This term is also used to refer to Gosper's original breeder, which periodically creates p30 glider guns. Breeders generally fall into one of four types, although in rare instances (mainly involving slide guns) breeders can be built that do not explicitly fit into one of these categories:
- MMS breeder - A moving object generates puffers periodically. Examples include Riley's breeder, metacatacryst, Jaws and pufferfish breeder.
- MSM breeder - A puffer that produces guns. Gosper's original breeder was a MSM breeder; so was Lucas Brown's LWSS breeder.
- SMM breeder - A stationary object that produces rakes. This is more commonly referred to as a rake gun.
- MMM breeder - A moving pattern that produces rakes periodically.
An unusual type of breeder, which can be loosely categorised as a MMS breeder, is the spacefiller. This does not create puffers in the classical sense, but instead stretches an infinite line of wickstretchers.
Many small quadratic growth patterns, for example mosquito 5, utilize switch engines because of their relative inexpense to construct, compared to the next easiest linear growth pattern, the Gosper glider gun.
The original breeder
- Main article: Breeder 1
The original breeder is composed of several rakes. These produce periodic waves of gliders, which collide to incrementally form guns. These guns then produce a steady output of gliders. Since the guns themselves are producing gliders at a linear rate, and the guns are being created also at a linear rate, the whole pattern grows quadratically. Since then, numerous improvements have been made. For example, Helmut Postl has made a much more compact version of the original breeder.
- Breeder at the Life Lexicon